J.B. Edmond Undergraduate Student Paper Competition
Repellency Effects of Incorporated Worm Castings and Compost Tea Sprays on Whitefly Populations for Poinsettia Production (Euphorbia pulcherrima)
Erin L. Cathcart*, Patrick N. Williams, and Kris-Ann E. Kaiser, Department of Agricultural Sciences, 213 S. Oakley Applied Science, Murray State University, Murray, KY 42071-3345
Every year the Murray State University horticulture program produces poinsettias for holiday sales. Fungicidal drenches and systemic insecticides are used to control soilborne pathogens and whitefly populations. This one crop uses more chemicals than any other crop during the year and without some type of control, a salable plant would not be possible. There were four experimental treatments each with four repetitions using a randomized block design: treatment 1, control containing no worm castings or compost tea sprays; treatment 2, 10% worm castings incorporated in the commercial growing substrate only; treatment 3, 10% worm castings incorporated and sprayed with the worm compost tea; and treatment 4, worm compost tea sprays only. Compost tea was applied every 2 weeks. Pinching, watering, shading, and fertilization followed a normally recommended schedule for production. No significant differences were found among treatments, but were found between repetitions and benches. Whitefly counts ranged from 130 to 1374 per plant, and none were considered marketable.
Shortening Germination Periods for California Poppy (Eschscholzia californica) Using Incubated Worm Casting Substrates
William T. Criner*, Justin D. Sparks, Patrick N. Williams, and Kris-Ann E. Kaiser, Department of Agricultural Sciences, 213 S. Oakley Applied Science, Murray State University, Murray, KY 42071-3345
One-year-old worm castings were added to Pro Mix BX® substrate at 20% by volume and incubated at a substrate temperature of 22.2 °C (72 °F) to observe germination rates of California poppy (Eschscholzia californica). Three different treatments were studied to determine the shortest germination periods: treatment 1, control received no incubation period; treatment 2, incubated for 7 days; and treatment 3, incubated for 14 days. Dechlorinated water was used throughout the study to reduce effects of chlorine on microorganism populations. Normal germination rates and range for California poppy are between 60% to 70% at 21 days. Treatments 2 and 3 were significantly different for germination percentage on days 10, 12 and 14 at P ≤ 0.001 over treatment 1. Treatments 2 and 3 had germination percentages higher than normal from 76% to 82% on days 10, 12, and 14. Treatment 1 germination rate was within normal range on day 10, but exceeded normal range for days 12 and 14. Incubated worm casting substrate mixtures increased germination percentages and reduced days to germination.
Landscaping for Water Quality: Designing a Demonstration Garden for the Friends of Lake Keowee Society Headquarters
David Warren* and Mary Haque, Department of Horticulture, Clemson University, Clemson, SC 29634
Clemson University Landscape Design students along with the Friends of Lake Keowee Society (FOLKS) joined together in an effort to create a demonstration garden to help educate the community about protecting Lake Keowee and its surrounding watersheds. In order to accomplish the goals of the project, the team followed a five-step landscape design methodology that included research, site analysis, conceptual design, preliminary design, and final design. The design showcases different low impact development (LID) techniques that improve water quality. A few examples of low impact development (LID) techniques used in the design include constructed wetland, rain garden, rain barrel, porous pavements, and shoreline buffer. These demonstration features will help educate the community about the importance of landscaping for water quality.
Nitrogen Mineralization in Greenhouse Turnips (Brassica campestris L.) Amended with Compost and Organic Fertilizer
Rachel Ben-Avraham*, Danielle Treadwell, and Mike Alligood, Department of Horticultural Sciences, University of Florida, Gainesville, FL 32611-0690
Organic fertilizers, unlike inorganic fertilizers, depend on biological and chemical processes to release plant available nitrogen. The purpose of this study was to determine the effect of organic matter on mineralization of nitrogen from organic fertilizers. Turnips were grown in pots in a polyethylene fan and pad greenhouse under four levels of organic matter (OM) that were made using commercially available mushroom compost and builder's sand to simulate typical OM content in Florida soils (0%, 1%, 2%, and 4%). Two different fertilizers approved for use in organic production, Perdue 4-2-3, and Nature Safe 8-5-5, and two sources of inorganic fertilizer, CaNO3 (15.5-0-0) and NH4SO4 (21-0-0), were added at the same concentration of N-P2O-K2O. Treatments were analyzed over 7 weeks for plant available nitrogen in pot media solution and plant nitrogen content. Both OM and fertilizer source affected plant available nitrogen, but there was no interaction between the two factors. Mineral nitrogen increased as OM increased in every week. Plant available nitrogen (mg N/kg media) in week 7 increased as organic matter increased when averaged over fertilizer sources (16.2%, 44.2%, 62.7%, and 82.4% for 0%, 1%, 2%, and 4% OM, respectively). Plant available nitrogen was greatest with inorganic fertilizers compared to organic fertilizers, whereas organic fertilizers followed similar trends to the control, with no fertilizer. Organic 4-2-3 and NH4SO4 had higher plant nitrogen contents than the other treatments. Within fertilizer source, plant nitrogen generally increased with increasing OM except in the case of organic 4-2-3 + 2% OM. In the 7 weeks of this study, mineral nitrogen in pot media solution with the inorganic fertilizer treatments was greater than the organic fertilizer treatments. The greatest differences in mineral nitrogen and plant nitrogen content were observed with increasing soil OM, illustrating the benefits of having soils high in organic matter.
Norman F. Childers MS Graduate Student Paper Competition
Utilization of Commercially Available Pollenizers for Optimizing Triploid Watermelon Production
Peter J. Dittmar*1, David W. Monks1, and Jonathan R. Schultheis1, 1North Carolina State University, Department of Horticultural Science, Raleigh, NC 27695-7609
Different planting arrangements of diploid (pollenizer) watermelon cultivars were tested for optimizing yield and fruit quality of triploid (seedless) watermelon fruit. The treatments with one pollenizer cultivar included ‘Companion’, ‘Super Pollenizer 1’ (‘SP1’), and ‘Summer Flavor 800’ (‘SF800’). The treatments with a combination of two pollenizers included ‘Companion’ + ‘SP1’, ‘Companion’ + ‘SF800’, and ‘SP1’ + ‘SF800’. Plant arrangement was compared by planting ‘SF800’ in a hill and inter-planted method. Transplant timing of pollenizers was compared by planting ‘SP1’ at the same time as the triploid plants and 3 weeks after triploid transplanting. The final treatment contained no pollenizer to determine if there was pollen movement between plots. There was some pollen movement between plots; however, it was minimal as fruit set in the no pollenizer plots was less than 12% of the highest yielding treated plot. For the individual pollenizers in 2005, plots with ‘Companion’ had the largest individual triploid fruit weight compared to ‘Mickylee’, ‘SP1’, or ‘SF800’. ‘Companion’, ‘Mickylee’, or ‘SP1’ resulted in greater marketable triploid fruit yield than ‘SF800’ in 2005. In 2006, using only ‘Companion’ had greater yields than ‘SF800’. ‘SF800’ had fewer triploid fruit with hollow heart than ‘Companion’. Combining ‘SP1’ or ‘SF800’ with ‘Companion’ decreased individual fruit weight in 2005 compared to ‘Companion’ planted alone. However, combining ‘Companion’ + ‘SF800’ increased individual triploid fruit weight compared to ‘SF800’ planted alone. ‘SF800’ + ‘Companion’ in 2005 and ‘SP1’ + ‘Companion’ in 2006 increased marketable yield compared ‘SF800’ or ‘SP1’ pollenizers planted alone. Planting pollenizers in the hill decreased triploid yields compared to inter-planting the pollenizer. Transplanting ‘SP1’ 3 weeks after the triploid plants decreased marketable yields and increased the severity of hollow heart in the triploid fruit. Growers should consider pollenizer selection, planting arrangement, and time of transplanting to optimize triploid production.
Staking, Guying, and Root Ball Anchoring: The Efficacy of Tree Stabilization Systems Installed on Recently Transplanted Trees
Alexis A. Alvey* and P. Eric Wiseman, Department of Forestry, Virginia Tech, Blacksburg, VA 24061-0324
Recently transplanted landscape trees are prone to destabilization from wind gusts. Various forms of staking and guying are used to prevent tree destabilization, but little scientific evidence exists for their efficacy. In this experiment, the efficacy of three generic tree stabilization systems (TSS) was tested. In Spring 2006, 24 balled and burlapped white ash (Fraxinus americana ‘Autumn Purple’) were transplanted to a field site in Blacksburg, Va. At planting, one of four TSS treatments (staking, guying, root ball anchoring, or control) was installed on each tree. Five weeks after planting, destabilization tests were conducted on the trees using a cable winch mounted to a skid-steer loader. First, a force simulating a 55 mph wind gust was applied to each tree. Destabilization was significantly greater for control trees (mean of 16° from vertical) than for trees with TSS (all means less than 3° from vertical). However, there was no significant difference in destabilization among TSS types. Each tree with a TSS was then stressed to complete system failure. The guying system endured significantly greater force before failure than the staking and root ball anchoring systems. The staking system endured significantly less force than the other two systems. The material costs and installation time for each TSS were also evaluated. The staking system was twice as expensive ($7.03) as the guying ($3.31) and root ball anchoring ($3.00) systems. All three systems took between 5 and 6 minutes to install. The guying system required significantly greater time to install than the root ball anchoring system, which did not significantly differ from the staking system. Based on our results, TSS protect recently transplanted landscape trees from destabilization by heavy wind gusts. From a practical standpoint, there were negligible differences among the TSS in terms of failure force and installation time. However, the staking system was twice as expensive as the other two systems, which may warrant consideration when choosing a TSS.
Response of Texas and Florida Live Oak (Quercus virginiana) Seedlings to Water Deficit Treatments
Amber Bonds* and Thayne Montague, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409-2122
Live oak (Quercus virginiana) is a common landscape tree in much of the United States. Although in native areas live oak can be found in mesic and xeric climates, little research has been conducted to determine if provenance differences exist in the response of live oak to deficit irrigation. Therefore, this research investigated gas exchange in response to water deficit irrigation treatments of live oak seedlings from a mesic region Groveland, Fla. (USDA Hardiness zone 9), and a xeric region, Justiceburg, TX (central Texas) (USDA Hardiness Zone 7). In May 2006, 1-year-old live oak seedlings were shipped to Texas Tech from Groveland, Fla. Acorns from Justiceburg were collected from several trees in Oct. 2005. Acorns were germinated and planted according to standard nursery practices. In June 2006, all seedlings were placed outside under shadecloth for 2 weeks and then in full sun for a month to acclimatize. Twenty-one seedlings from each location were brought into a greenhouse, assigned one of three watering treatments (control seedlings were watered every day; moderate water deficit seedlings were watered every other day; and severe water deficit seedlings were watered every fourth day), and arranged in randomized complete blocks. Mid-day stomatal conductance and leaf temperature were measured every fourth day prior to irrigation of severe drought seedlings. Outdoors, prior to irrigation treatments seedlings from Texas had greater stomatal conductance and lower leaf to air vapor pressure deficit (LVPD) when compared to seedlings from Florida. In the greenhouse, seedling gas exchange was influenced by water deficit treatment and provenance. Stomatal conductance and LVPD for Texas seedlings did not differ among water deficit treatments. However, Florida seedlings exposed to severe drought had lower stomatal conductance and a greater LVPD than seedlings exposed to control or moderate irrigation treatments. Regardless of irrigation treatment, seedlings from Texas had greater stomatal conductance and lower LVPD when compared to Florida seedlings. Our data indicate that the response of live oak seedlings from central Texas and Groveland, Fla, differs in their response to water deficit treatments and that live oak trees from central Texas may be better adapted to xeric sites than live oaks from a more mesic environment.
Influence of Four Salinity Treatments on Growth and Leaf Nutrient Content of Three Taxodium Genotypes
Lijing Zhou* and Dave Creech, SFA Mast Arboretum, P.O. Box 13000, Stephen F. Austin State University, Nacogdoches, TX 75962
Abbreviated as BC, MC, and hybrid in this abstract, baldcypress (Taxodium distichum L Rich var. distichum), montezuma cypress (Taxodium distichum var. mexicana Gordon), and Taxodium × ‘Nanjing Beauty’ (a hybrid, BC × MC) were subjected to acute applications of four salt rates in a container study. Beginning 22 May 2006, zero, low, medium, and high rates of sea salt solutions were applied one time per week for 13 weeks (0, 17, 60, and 103 mol·m−3). When no salt damage was evident, the decision was made to double the rate (0, 34, 120, and 206 mol·m−3), and this protocol was continued for another 12 weeks. Plants were harvested on 15 Nov. 2006. A two-way factorial design with four randomized blocks was utilized. Irrigation between salt solution applications was via sprinkler when needed. Leachate readings via the pour-through method indicated that only one sprinkler irrigation was needed to bring substrate conductivity down to just above background. During the 24-hour exposure periods, roots were subjected to conductivities approaching 20 decisiemens/m with the high rates. In spite of doubling the rate in midcourse of this experiment, all plants survived and few exhibited salt damage symptoms. There was no significant salt rate effect on growth, as determined by the wet weight of aboveground parts. There were genotype differences. The hybrid produced higher wet weights than BC and MC. However, MC exhibited the greatest increase in height of the three genotypes. The explanation is growth habit differences. The cutting-grown hybrid was heavily branched and plagiotropic, while MC enjoyed a strong leader. Na concentration in Taxodium leaves increased as sea salt concentrations increased. The K:Na ratio in Taxodium leaves decreased as salt concentration increased. Of three Taxodium genotypes, BC exhibited the highest leaf content of Na, Ca, and S; MC had the lowest leaf content of Na, Ca, and S; the hybrid was in-between. Work plans include repeating this experiment but at much higher rates, and field trials of germplasm in saline locations in East Texas.
Influence of a Modified Pot-in-pot Production Strategy on Root Temperature and Growth of Rhododendron × ‘Mrs. G.G. Gerbing’ in Full Sun
Brennan Whitehead* and David Creech, Department of Agriculture, P.O. Box 13000, Stephen F. Austin State University, Nacogdoches, TX 75962
In Texas, container plants in nurseries can experience excessive container temperatures, particularly during the hot summer months. Root damage can be severe and plant quality can lower. A raised bed, double-row pot-in-pot production research plot (200 ft × 6 ft) was established at the north end of the SFA Mast Arboretum with sockets in a triangular design with plants 24 inches apart in rows 8 inches apart (3.45 square ft per socket pot). This design was basically a modification of the Jay Fraleigh Nursery GRO-ECO (U.S. Patent No. 6,865,845) strategy in a full sun site. This study monitored the influence of black or white weed barrier, or whether a “mid-irrigation line” was used or not on growth of Rhododendron ‘Mrs. G.G. Gerbing’ plants. The mid-irrigation line (emitters 12 inches apart) was oriented between the two rows of socket pots and intended to apply light, frequent irrigations in such a way that they cool the soil and nearby socket pots. A randomized block design was used with six blocks containing the four treatments. A total of 196 azalea containers used in this portion of the study, which began 7 Apr. 2006 and was terminated 7 Oct. 2006. All plants were irrigated with a single emitter. Records of the time and volume of irrigation were kept throughout the study. The rate and timing of fertilization (OsmocoteR 18–6–12) were adjusted throughout the trial based on conductivity readings. The growth and root temperature data from the pot-in-pot research plot were compared to data collected from a full sun aboveground container area and a 50% shade house area. Temperature readings were taken at the edge, center, and bottom of the containers in the three areas during the hottest time of the summer. Plant height and dry weight were measured at the termination of the experiment. A repeated measures ANOVA was performed on the temperature data. A randomized block ANOVA test was performed on the dry weight and height of the plants. When statistically analyzed, there were no significant differences in container temperatures or growth between the four treatments. The pot-in-pot azaleas were superior when compared to plants grown in a nearby full sun aboveground area and the 50% shade house by the horticulture facility. While not analyzed because of location differences, the pot-in-pot azaleas were more uniform, of good color, and had a strong root system.
Consumer Preference and Postharvest Life of Field-grown Fresh-cut Sunflowers
Kara Howard*1, Ellen Peffley1, Jorge Vizcarra2, and Chad Davis3, 1Department of Plant and Soil Science, P.O. Box 42122, Texas Tech University, Lubbock, TX 79409; 2Department of Animal and Food Sciences, P.O. Box 42141, Lubbock, TX 79409; 3Department of Agricultural Education and Communications, P.O. Box 42131, Lubbock, TX 79404
There is a developing market for field-grown cut flowers in Texas. The overall goal of this study was to identify a floral crop that could be field grown in the Texas South Plains and marketed freshly-cut. A survey of Lubbock, Texas, florists revealed sunflowers (Helianthus annuus L.) were favored by most. Sunflower is a crop grown on 54,000 acres in Texas harvested for either seed or oil. Since agronomic cultivars were already in production in our area, they were included in this study to determine if they had value as a cut flower crop. Eight agronomic and eight ornamental sunflower cultivars were grown in a variety trial in Summer 2006 in a completely randomized block design. To learn which cultivar consumers preferred, a study was conducted where stems were harvested and photographed when blooms were at “partly open” and “fully open” stages. Florists and Texas Tech University students participated in an online sunflower cultivar survey that included the sunflower images, where florists were asked if they would use the cultivar for sale, and students if they would buy the cultivar. Mean ratings of responses were determined for each cultivar. Both groups gave high mean ratings to agronomic and ornamental cultivars. Florists responded they would sell agronomic cultivars and students responded they would buy agronomic cultivars. Demographic data were collected and are being analyzed. In a second study, postharvest life of cut stems was investigated. When ray florets were open 45°, stems were harvested and held in double-distilled (DD) water or floral preservative in a factorial arrangement of treatments. Ten days is an industry standard for postharvest life of cut flowers. Most sunflower cultivars in this study met or exceeded the 10-day mark regardless if held in DD water or floral preservative. Some cultivars demonstrated a significantly longer postharvest life when in floral preservative than when in DD water. Significant differences in postharvest life also occurred between some cultivars.
Timing of Herbicide Application Affects Weed Control
Diana R. Cochran*1, Charles H. Gilliam1, D.J. Eakes1, Glenn R. Wehtje1, Patricia R. Knight2, and James Altland3, 1101 Funchess Hall, Department of Horticulture, Auburn University, Auburn, AL 36849; 2Mississippi State University, Coastal Research and Extension Center, Biloxi, MS 39532; 3North Willamette Research and Extension Center, Oregon State University, Aurora, OR 97002
This study evaluated three herbicides, BroadStar (150 lb/acre), Rout (100 lb/acre), and Snapshot (200 lb/acre), applied at 0, 3, 7, and 10 days after seeding (DAS) trade gallon containers with Eclipta alba (eclipta) or Euphorbia maculata (spotted spurge) at 25 seed per container. Each container was filled with a pinebark : sand 6:1 (v:v) medium amended with Polyon 17–6–12 (17N–2.6P–10K) at 6.35 kg·m−1 control-release fertilizer, dolomitic lime at 2.27 kg·m−1, and micromax at 0.89 kg·m−1. Data were collected at 7, 14, 28, 38, 45, and 60 DAS and weed fresh weights at 60 DAS. Results indicated BroadStar, Rout, and Snapshot applied at either 0 or 3 DAS resulted in similar eclipta and spotted spurge control. When comparing eclipta numbers at 7 and 28 DAS, weed numbers were reduced by BroadStar (87%), Rout (70%), and Snapshot (48%) when applied at 7 DAS. Similarly, eclipta numbers were reduced by BroadStar (85%), Rout (73%), and Snapshot (48%) when applied at 10 DAS. With spotted spurge, weed number was reduced at 28 DAS when BroadStar (94%), Rout (85%), and Snapshot (51%) were applied 7 DAS. Similarly, at 10 DAS spotted spurge number was reduced by BroadStar (96%), Rout (56%), and Snapshot (53%) at 28 DAS. These data show BroadStar, Rout, and Snapshot have limited postemergent control of Eclipta alba and Euphorbia maculata when applied soon after germination.
Growth Modification of Bedding Plants using ChromatiNeting
Charles R. McElhannon*, R.J. Kessler, G.J. Keever, and W.G. Foshee, Horticulture Department, Auburn University, 101 Funchess Hall, Auburn, AL 36849
Commercial markets require growers of bedding plants to produce a product which has uniform height and is within preset specifications. Chemical applications of plant growth retardants (PGRs) have been used for decades to reduce internode extension. The use of photoselective filters as an alternative to PGRs has been studied since the early 1990s and has been shown to modify plant growth. Five colors of ChromatiNeting, a photoselective filter produced by Polysac, were used to determine growth responses of six bedding plants (Dianthus barbatus ‘Dynasty Red’, Lycopersicon lycopersicum ‘Sun Leaper’, Capsicum annuum ‘Sweet X3R Camelot Hybrid’, Ipomoea tricolor ‘Crimson Rambler’, Brassica oleracea ‘Patron’, and Brassica oleracea ‘Blue Vantage’) in a double polycarbonate greenhouse in Auburn, AL. Each ChromatiNeting color and a control of ambient light conditions were replicated 3 times in a randomized complete-block design. Plant height and two widths, from which a growth index was calculated, were measured at 2 and 5 weeks after transplanting. Black ChromatiNeting reduced shoot height in dianthus, pepper, morning glory, broccoli, and cabbage but shoot height was the same as blue and gray in several cases. Pearl ChromatiNeting yielded the tallest plants in tomato, pepper, morning glory, broccoli, and cabbage but these plants were the same height as ambient light or red in several cases. Black ChromatiNeting resulted in the lower GI in dianthus, tomato, pepper, morning glory, broccoli, and cabbage but blue and gray resulted in the same GI in several cases. Pearl ChromatiNeting yielded larger GI in dianthus, tomato, pepper, morning glory, broccoli, and cabbage but ambient light and red resulted in the same GI in several cases. ChromatiNeting has potential as a growth-modifying photoselective filter; however, more studies are needed to identify responses of different species.
The Effect of Drought on Root Growth of Two Native Landscape Shrub Species
Matthew F. Wilkin*, Amy N. Wright, Robert C. Ebel, and D. Joe Eakes, 101 Funchess Hall, Horticulture Department, Auburn University, Auburn, AL 36849
Understanding plant response to drought can provide insight into irrigation requirements and relative drought tolerance of landscape shrub species. The objective of this study was to utilize the Horhizotron™ to evaluate root growth of Myrica cerifera L. (wax myrtle) and Illicium floridanum Ellis (Florida anise tree) when portions of the root system are exposed to different levels of soil moisture. Myrica cerifera and I. floridanum were placed in Horhizotrons on 9 Feb. and 15 June, respectively. Quadrants were filled with Greens Grade™ Profile™ amended at a standard nursery rate. Four irrigation frequencies were randomly assigned to quadrants in each Horhizotron: substrate watered daily (≈20% moisture by volume), substrate rewatered once dried to 15% moisture, substrate rewatered once dried to 10% moisture, and an unwatered substrate. Daily 400 mL water was applied to the root ball, and when watered, quadrants received 400 mL water. Weekly root growth measurements were taken by measuring horizontal root length (parallel to the ground) of five longest roots visible on each side of a quadrant. Dry weight of roots in each quadrant was determined for M. cerifera and I. floridanum on 79 and 107 days after planting, respectively. Myrica cerifera root lengths were lowest in the unwatered substrate, while root lengths in all other substrates did not differ. Illicium floridanum root lengths in the substrate watered daily and in that rewatered at 15% moisture were similar and higher than in substrate rewatered at 10% moisture or in the unwatered substrate. Myrica cerifera root dry weight was lower in the unwatered substrate than in the well-watered substrate, similar to root lengths. Illicium floridanum root dry weights in the daily watered treatment and in that rewatered at 15% moisture were similar and higher than in the other substrates. This experiment indicates that root growth of M. cerifera and I. floridanum can persist as long as some portion of the root system is receiving some water.
Mulch Type Influences Root Growth of Native Woody Shrub Species
Julie L. Guckenberger* and Amy N. Wright, Department of Horticulture, 101 Funchess Hall, Auburn University, Auburn, AL 36849
Development of a root system into the surrounding soil is essential for survival of transplanted container-grown plants. The need for reliable planting techniques that encourage root growth in adverse conditions has prompted research into planting above grade. Myrica cerifera (wax myrtle) and Illicium floridanum (Florida anise tree) plants were removed from their containers and planted in Horhizotrons in a greenhouse in Auburn, Ala., on 1 Mar. and 6 June 2006, respectively. The Horhizotron contains four glass quadrants extending away from the root ball, providing a nondestructive method for measuring root growth over time of roots of the same plant into different rhizosphere conditions. Each quadrant was filled with 100% soil in the lower 10 cm. The upper 10 cm of the quadrants were filled randomly with either: 1) pine bark (PB); 2) peat (P); 3) cotton gin compost (CGC); or 4) more soil (100% soil, no mulch control). This practice was intended to simulate the above-grade planting practice with the lower half the root ball in soil and upper half in mulch. Horizontal root lengths (length measured parallel to the ground) of the five longest roots visible along each side of a quadrant were measured weekly. At 44 days after planting (DAP), roots of M. cerifera were longer in quadrants with CGC or P than in PB or 100% soil, and roots grew into both the upper mulch and lower soil layers. Myrica cerifera root dry weights were similar among treatments, illustrating the importance of measuring root length over time to determine extent of root development laterally into the treatments. At 115 DAP, roots of I. floridanum were longest in quadrants with P or PB than in CGC or 100% soil, and roots grew mostly into the mulch layers. Illicium floridanum root dry weights were highest in P and PB. Results suggest that utilizing the above-grade planting technique can increase post-transplant root growth of native woody shrubs over traditional planting in 100% soil.
Using Degree Days to Predict Nitrogen Mineralization from Organic Amendments
Alejandra Sierra*1, Danielle Treadwell1, Eric Simonne1, and Donald Graetz2, 1Department of Horticultural Science, P.O. Box 110690, University of Florida, Gainesville, FL 32611-0690; 2Soil and Water Science Department, P.O. Box 110510, University of Florida, Gainesville, FL 32611-0510
Crop nutrition in organic production is based mainly on the decomposition of plant and animal-based organic amendments. Environmental factors such as temperature play an important role in the mineralization and nitrification of nitrogen (N). In the past, growing degree days have been successfully used to predict N release from crop residues and manures. A 5-week study was conducted during two seasons (spring and summer) and two locations (greenhouse and lab) to evaluate the utility of cumulative degree days (CDD) for predicting the ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) release rate from five organic amendments: blood meal (BLM), feather meal (FM), bone meal (BM), rock phosphate (RP) and potassium magnesium sulfate (SPM) and two controls: an inorganic fertilizer (CON) and potting media with no amendment (NA). Amendments were mixed with an approved organic potting media at a 1 to 5 ratio and maintained at constant moisture. Temperature of the air was recorded in 15-minute intervals using a data logger and was used to calculate degree days (DD). The NH4+-N and NO3−-N release rates were determined from leachate samples taken every week throughout the study. The rate of NH4+-N and NO3−-N release rates increased with increasing temperature, and could be predicted across locations and seasons using CDD. NH4+-N cumulative release rate from NA (Y = 0.00029CDD, R2 = 0.35), FM (Y = 0.003845 CDD, R2 = 0.61), BLM (Y = 0.03630CDD, R2 = 0.62) and CON (Y = 0.0139CDD, R2 = 0.95) had a linear response to CCD. Similar to NH4+-N, NO3−-N release rates had a linear response to CDD for all treatments (NA Y = 0.00219CDD, R2 = 0.28; FM Y = –2.26 + 0.01029CDD, R2 = 0.76; BLM Y = –1.92 + 0.00878CDD, R2 = 0.73; BM Y = 0.01087CDD, R2 = 0.54; RP Y = 0.0039CDD, R2 = 0.29; SPM Y = 1.176 + 0.0025CDD, R2 = 0.60; CON Y = 1.29 + 0.0367CDD, R2 = 0.98). Degree days are a potential tool to predict N mineralization and nitrification from organic amendments, and therefore synchronize release with plant N requirements.
Sudden Inundation Effects on Urban Landscape Plants
Karen Blackburn* and Ed Bush, LSU AgCenter Department of Horticulture, Louisiana State University, Baton Rouge, LA 70803-1068
On 29 Aug. 2005 Hurricane Katrina caused significant flooding of the New Orleans metropolitan area for durations of up to 4 weeks in certain locations. A study to evaluate the differential urban landscape plant survival was initiated 1 Oct. 2006. Nine woody ornamental species were evaluated for sudden inundation tolerance. Plant species evaluated included three groundcovers (asian jasmine, liriope, and green mondograss, three shrub species (azalea, japanese yew, yaupon holly) and three tree species (crape myrtle, live oak, southern magnolia). Inundation treatments consisted of three depths (0%, 50%, and 100% of canopy) and two durations (2 and 4 weeks). Species, flooding depth, and duration affected each species differently. Asian jasmine at both durations and depths resulted in mortality. Liriope and mondograss showed tolerance at 50% and 100% flooding depths and both durations. Azalea plants submerged for both depths resulted in a reduction in plant quality. Plants submerged at 100% for both 2 and 4 weeks resulted in dead plants as witnessed in New Orleans following Katrina. Japanese yew leaves submerged at 50% were damaged, but leaves surviving above the waterline remained intact. These plants seemed to localize foliar damage. Yaupon holly plants showed similar results. Southern magnolia trees resulted in complete mortality with 50% and 100% inundation and both depths. Crape myrtle plants showed no differences among inundation treatments of 50% and 100%. All treatments showed decreased quality compared to the control. Magnolia trees in the most damaged sections of New Orleans also resulted in mortality. Live oak trees performed best of the three tree species. Although inundation treatments reduced plant quality, trees survived both flooding depths and durations. Overall, the results of the inundation study were similar to the actual flooding from Hurricane Katrina.
Warren S. Barham PhD Graduate Student Paper Competition
Semi-quantitative Measurement of Carotenoid Development in Four Watermelon Colors: A Discussion of the Impact of Ploidy and Other Genetic Factors
Jennifer Waters*1, Haejeen Bang1, Angela Davis2, Daniel Leskovar3, and Stephen King1, 1Vegetable and Fruit Improvement Center Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843; 2SCARL, USDA-ARS, Lane, OK 74555; 3VFIC, Department of Horticultural Sciences, TAES, Uvalde, TX 78801
Carotenoids are important health-promoting compounds which act through their anti-oxidant activity to reduce the risk of some cancers, heart disease, macular degeneration, and may even improve immune responses. Watermelon is an important source of lycopene and other carotenoids. Understanding the development of these compounds in the growing fruit may improve our ability to promote increased levels or accumulation of specific carotenoids. This study measured the accumulation of 35 carotenoid species at four time points post-pollination (10, 20, 40, and 55 days) in four watermelon colors at two ploidy levels (2n and 3n). The resulting patterns of development align well with putative dominance regiments, known points of mutation in the pathway, and may be able to predict other disruptions leading to color change. From this, hypotheses about regulation of the watermelon carotenogenic pathway were formulated. Finally, this developmental data show fundamental differences in patterns of carotenoid development between diploid and triploid varieties. It is critical to understand the construction and regulation of the carotenoid pathway before successful attempts can be made in manipulating the pathway to obtain a product of even higher health-promoting potential.
Clean Chip Residual Substrate for Container-grown Perennials: Effect of Supplemental Nitrogen Rates
Cheryl R. Boyer*1, Glenn B. Fain2, Charles H. Gilliam1, Thomas V. Gallagher3, H. Allen Torbert4, and Jeff L. Sibley1, 1101 Funchess Hall, Horticulture Department, Auburn Univ., Auburn, AL 36849; 2USDA–ARS Southern Horticultural Laboratory, Poplarville, MS 39470; 3Department of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849; 4USDA–ARS National Soil Dynamics Laboratory, Auburn, AL 36832
Clean chip residual (CCR) is composed of pinebark (PB) (≈42%), needles (≈9%), and wood (≈49%) from residue remaining after in-field harvesting of pine wood chips for the paper industry. This study utilized aged (6 months) pinebark and fresh CCR in combination with four rates of supplemental nitrogen (0, 0.23, 0.45, 0.68 kg·m−3 N; 42N–0P–0K Polyon coated urea). Treatments were amended with 6.35 kg·m−3 Polyon 18N–2.6P–10K, 2.27 kg·m−3 dolomitic limestone and 0.68 kg·m−3 MicroMax. On 6 June 2006 liners (72 cell pack) of buddleia (Buddleia davidii ‘Pink Delight’), gaura (Gaura lindheimeri ‘Siskiyou Pink’), and coreopsis (Coreopsis rosea ‘Sweet Dreams’) were transplanted into (2.8-L) containers, placed outside in full sun, and overhead irrigated as needed. Pour-through extractions were conducted at 1, 15, 30, 60, and 90 days after planting (DAP) to determine pH and electrical conductivity (EC). Leaf chlorophyll content was quantified at 30, 60, and 100 DAP on buddleia. Growth indices were recorded at 30, 60, and 90 DAP. Flower numbers were counted at 60 and 90 DAP (buddleia). Substrate shrinkage was recorded at 7 and 90 DAP. Shoot dry weight and percent rootball coverage were recorded at 100 DAP. Plant growth indices (90 DAP), percent rootball coverage, shoot dry weight, and substrate shrinkage at the end of the study were similar among all species for substrate and fertilizer effects. Leaf chlorophyll content of buddleia was also similar at 90 DAP for all treatments. Flower number was similar for both substrate and fertilizer effect for buddleia at 90 DAP and gaura at 60 DAP while coreopsis exhibited a slight substrate effect at 60 DAP with plants grown in PB having more flowers than those grown in CCR. EC and pH levels were within acceptable ranges throughout the study. Results indicate that buddliea, gaura, and coreopsis exhibit similar growth when grown in PB or CCR and do not require supplemental nitrogen during production.
Identification of Molecular Markers Associated with Sweetpotato Resistance to Sweet Potato Virus Disease
Douglas W. Miano*1, Don R. LaBonte1, and Christopher A. Clark2, 1Department of Horticulture, Louisiana State University Agricultural Center, Louisiana Agricultural Experimental Station, Baton Rouge, LA 70803; 2Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Louisiana Agricultural Experimental Station, Baton Rouge, LA 70803
A total of 47 unrelated sweetpotato genotypes were selected and classified into two phenotypic groups as resistant or susceptible to sweet potato virus disease (SPVD). Amplified fragment length polymorphism (AFLP) marker profiles were generated for each individual and used in association studies to identify markers suitable for identification of plants possessing a resistant reaction to SPVD. AMOVA analysis found significant (P < 0.002) variation between the two phenotypic groups using 206 polymorphic AFLP markers. Discriminant analysis and logistic regression statistical methods were used to select informative markers, and to develop models that would classify the two groups. A training set of 30 (from the 47) genotypes, consisting of 15 grouped as resistant and 15 grouped as susceptible, was used to develop the classification models. Four similar markers, which gave a 100% correct classification of the training set, were selected by both discriminant and logistic regression analysis. A classification model consisting of the four markers gave a 94% correct classification of the 17 genotypes used as test groups.
Morphological and Physiological Studies on Liriope and Ophiopogon Species
Catherine Broussard*and Ed Bush, 128 Julian C. Miller Hall, Department of Horticulture, LSU Agricultural Center, Baton Rouge, LA 70803
Morphological and physiological studies have been performed on liriope and ophiopogon (collectively referred to as liriopogons) to gain factual evidence and clear up misnomers in the nursery industry. Flower and root characteristics have been described to assist green industry professionals in distinguishing between liriope and ophiopogon in addition to the individual species within these two genera. Root and flower morphology of 19 commonly used liriopogon cultivars were studied and categorized into two genera and eight species using taxonomic keys previously established by L.H. Bailey and H. Harold Hume. These were Liripe muscari (erect flowers, superior ovaries, tufted root system), L. spicata (erect flowers, superior ovaries, rhizomatous root system), L. exiflora (erect flowers, superior ovaries, rhizomatous root systems), L. gigantea (erect flowers, superior ovaries, rhizomatous root system); Ophiopogon japonicus (drooping flowers, semi inferior ovaries, rhizomatous root system), O. jaburan (drooping flowers, semi-inferior ovaries, tufted root system) and O. planiscapus (drooping flowers, semi inferior ovaries, rhizomatous root system). 13C and 15N analysis was performed on two species, resulting in determination of C3 mode of photosynthesis for liriopogons. Future studies will be performed on species by comparing root and flower characteristics of known species. This will assist the nursery industry in categorizing new cultivars such as ‘Cleopatra’, ‘Marc Anthony’, and ‘Emerald Goddess’.
Variation in Ecophysiological Traits of Mexican Pecan Provenances
Madhulika Sagaram*1, Leonardo Lombardini1, and L.J.Grauke2, 1Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843-2133; 2Pecan Genetics and Breeding Program, Agricultural Research Service, U.S. Department of Agriculture, 10200 FM50, Somerville, TX 77879
An assessment of leaf physiological traits of pecan provenances growing in Sommerville, Texas, was conducted during Summer 2006. The trees representing the provenances were grown from seeds collected from 19 locations chosen within the native range of pecan distribution. Thirteen sites were located in Mexico and six in the United States. The objective of the study was to provide an understanding of patterns of geographic variation within the natural range for physiological (net CO2 assimilation rate, stomatal conductance, transpiration, photosynthetic efficiency, and instantaneous water use efficiency) traits. No differences in net CO2 assimilation rate, stomatal conductance, transpiration, and instantaneous water use efficiency were observed between provenances. The study showed that photosynthetic efficiency of the tested provenances were significantly different (P < 0.05) in July as well as Aug. 2006. The provenance obtained from Saucillo (western Mexico) showed the highest values of photosynthetic efficiency during both the July and August measurements, whereas the provenances from eastern Mexico showed the lowest values. These results suggest that pecan provenances from a dry environment have a higher photosynthetic efficiency than provenances from humid environments. This study could provide useful information for a breeding program aimed at developing more drought-tolerant cultivars.
Obstacles to the Determination of Nitrogen Loads from Field-grown Tomatoes
Aparna Gazula*1, Eric Simonne1, Michael D. Dukes2, George J. Hochmuth1, Robert Hochmuth3, and David W. Studstill1, 1Horticultural Sciences Department, 1241 Fifield Hall, University of Florida, Gainesville, FL 32611-0690; 2Agricultual and Biological Engineering Department, 107 Frazier Rogers Hall, P.O. Box 110570, Gainesville, FL 32611; 3North Florida Research and Education Center–Suwannee Valley, 7580 County Road 136, Live Oak, FL 32060
With the development of total maximum daily load legislation, in-field nutrient load measurements are required to assess the impact of land use on groundwater quality. Our objective was to determine the effects of a combination of fertilizer and irrigation programs (N fertilizer at 100% or 200% IFAS recommended, and irrigation at 100% or 300% IFAS recommended rates) on soil mineral N load using three different width estimates: mean wetted width, maximum wetted width, and raised bed width under a plasticultured crop. Based on previous studies, we assumed 1) a rate of 2 cm/day of vertical water movement, 2) seasonal water movement of less than 1.5-m depth, and 3) a uniform distribution of fertilizer in the wetted zone. ‘Florida 47’ tomatoes were grown on Lakeland fine sand during 2005 and 2006. At the end of the tomato crop (75–80 days after transplanting), 1.5-m-deep soil samples were collected at the drip tape emitter from all the treatments. Seasonal NO3-N + NH4-N load from the six treatments ranged from 0.77 to 1.20 kg·ha−1, which was less than expected. Moreover, the coefficient of variation was 86%. The results suggest that the assumption that fertilizer is uniformly distributed in the wetted zone was likely incorrect and a high leaching zone may exist immediately below the drip tape. It is also likely that the rate of vertical water movement was greater than 2 cm/day, thereby moving fertilizer deeper than 1.5 m. Hence, sampling procedures for load determination from drip-irrigated plasticultured crops should be done multiple times and/or from greater depths, and should take into account nutrient distribution in the soil.
Success of the Pecan Management Course at Oklahoma State University
Eric T. Stafne*, B. Dean McCraw, and Becky L. Carroll, 360 Agricultural Hall, Department of Horticulture and Landscape Architecture, Stillwater, OK 74078
The pecan management course at Oklahoma State University is now in its 10th year. Initially it began as a 1- or 2-day course, but has expanded to being taught over a 9-month period. The current course has 32 student contact hours over eight class periods. New leadership of the course has prompted investigations into past attendance for needs assessment of future courses. Attendance numbers were compiled to determine appropriate course length, months in which to hold the course, and to discern any patterns evident over the 10-year period. An average of 33 persons attend the course per year with an average of 72% attendance over all months. Classes have varied in their average attendance over the 10 years, ranging from 57% attendance to 86%. Attendance appears to increase following “on” pecan harvest years and fall following “off” years. Price obtained for pecans may be a factor, but its impact was not immediately evident. Classes held early in the year are better attended than those during the summer, especially the month of August, likely due to competition with other activities. The data derived from past courses will allow for decision-making to improve course attendance in the future.
So, You Wanted to Accept the Null Hypothesis? Analysis and Interpretation of Fertilizer Trials in the BMP Era
Eric Simonne*, Monica Ozores-Hampton, Ramon Littell, Meagan Brennan, and Aparna Gazula, University of Florida, Horticultural Sciences Department, Gainesville, FL 32611-0690
With the development of best management practices, fertilizer recommendations have to reconcile profitability with environmental stewardship. On-farm fertilizer demonstrations and trials are needed to 1) validate statewide recommendations under different growing systems; 2) propose adjustments where needed; and 3) facilitate growers’ adoption. Statistical techniques such as analysis of variance, mean separation tests, and polynomial regression may not be enough when yield differences that need to be detected based on economical considerations are small compared to the inherent variability of field data. For example, using current prices, it takes approximately 4 to 10 25-lb/acre boxes of tomato to offset the price of N at 100 lbs/acre. Detecting yield differences of this magnitude may require an unpractical number of replications. Binomial distribution, power calculation, and nonlinear regression should also be considered for the analysis of on-farm fertilizer trials.
Teaching through Games
Mary Lamberts* and Christian Miller, UF Miami–Dade County Extension, 18710 SW 288th St., Homestead, FL 33030
The authors used two different “games” as Extension teaching strategies with several diverse audiences and have found advantages and disadvantages for both games. The first “game” is an exercise where participants had to find job-related information on program-specific pesticide labels and record it as teams or individuals. The second “game” is a variation on the television game show Jeopardy. For both games, the team or individuals with the most correct answers “wins” some type of “prize.” Audiences for the label reading games included Miami–Dade County Parks and Recreation Department employees, South Florida Aquatic Plant Management Society workshop attendees, and members of the South Florida Golf Course Superintendents Association. The two Jeopardy audiences included participants in a pesticide review class and a continuing education unit (CEU) workshop. Materials for the label game include portions of pesticide labels using a different color paper for each label, a worksheet on either legal or ledger paper, and a supply of pens or pencils. The Jeopardy game needs “money” and the game itself. Audience-appropriate “prizes” for the winning team or individual(s) are needed for both games.
Problems. When the label game was first used, instructors “graded” the results at the end of the session. This was very time consuming and difficult to do since some participants added unanticipated answers. A suggestion is to give teams the expected answers and possible points for each section and have each team's answers “graded” by another team. This would still allow for questions, but would greatly speed up the process. The problem with the Jeopardy games was that not all participants were equally familiar with the chosen subject matter categories. Some people knew most answers, while others just observed but may not have learned the desired information. This game has been more successful when used at the end of more traditional workshops since it serves as a novel review. Despite the problems, participants do enjoy learning through games. Games are highly interactive and can lead audience members to find information they might otherwise ignore. Prizes are expected, but are not the most important part.
A Regional Training Program for Methyl Bromide Transition: Regulatory Update, Alternatives Research, and On-farm Projects
R.M. Welker1, J.P. Smith*2, G.E. Fernandez3, D.W. Monks3, P.M. Brannen4, E.B. Poling3, and F.J. Louws1, 1Department of Plant Pathology, Gardner Hall 3403, Box 7616, NCSU Campus, Raleigh, NC 27695; 2CUCES–Lexington County, 605 W. Main St. Suite 109, Lexington, SC 29072; 3Department of Horticultural Sciences, Kilgore Hall 128, Box 7609, NCSU Campus, Raleigh, NC 27695; 4Department of Plant Pathology, 2106 Miller Plant Sciences Bldg., University of Georgia, Athens, GA 30602
A 2-year in-service training program supported by the Southern Region IPM Center, Southern Region Small Fruit Consortium, and the USDA Methyl Bromide Alternatives Program has familiarized 61 county agents and certified crop advisors with the current status of methyl bromide regulatory and availability issues, new concepts in mulch film technology, and completed and ongoing research into methyl bromide alternatives. Also, attendees reviewed and critiqued on-farm research/demonstration projects designed to show growers currently available methyl bromide alternatives, as well as discussing and planning needed on-farm work for the future. The training involved both classroom and hands-on activities designed along the “Train-the-Trainer” model in order to facilitate extension of the information to growers and other users of methyl bromide. Notebooks to be used in further training exercises were distributed and contained information on methyl bromide alternatives research, calibration spreadsheets for applications of methyl bromide alternatives using existing application equipment, high-barrier mulch film technology, and product information for new application equipment and techniques.
Making Fire Ants Easier to Live with: Alabama Cooperative Extension System's Fire Ant Education Program
Kathy Flanders*, 201 Extension Hall, Department of Entomology and Plant Pathology, Auburn University, AL 36849
Since 2000, the Alabama Cooperative Extension System (ACES) and the Alabama Fire Ant Management Program have conducted educational programs on imported fire ant management. Our sustainable approach to fire ant management makes fire ants easier to live with while reducing social, economic, and environmental costs. A tiered training approach was used. In 2000, forty county extension agents were trained in fire ant management. In 2001, educational publications and teaching materials were developed with input from these agents (www.aces.edu/dept/fireants). From 2002 to 2004, agents trained the next tier of trainers, called fire ant management advisers. By teaching those who are likely to pass on their knowledge, we multiplied our own training efforts. We estimate the impact of this program to be $1.3 million annually. Results from pre- and post-testing showed that we increased the knowledge of our fire ant management advisers by 29%. For every dollar spent we get at least $30 in savings for our stakeholders. In 2004, extension agents continued to conduct fire ant education programs. In addition, they started field demonstrations of bait-based management programs. Beginning in 2006, specialists and agents from ACES have been involved in developing imported fire ant eXtension, using a grant obtained from eXtension. The Alabama Cooperative Extension System is the lead institution on the grant. Imported fire ant eXtension will be launched to the public in Apr. 2006. Several other organizations have collaborated with ACES in implementing this program. Our partners include the Alabama Fire Ant Management Program, Alabama A&M University, USDA–ARS, USDA–APHIS, the Alabama Department of Agriculture and Industries, the Alabama Cattlemen's Association, the Southern Region SARE Professional Development Program, and eXtension.
Growing Farmers and Establishing Local Markets
John Braswell*1 and Nana Mejia2, 1Mississippi State University, P.O. Box 193, Poplarville, MS 39470; 2National Center for Appropriate Technology, 106 Crape Myrtle Circle, Covington, LA 70433
Local direct markets for selling locally grown food products in Mississippi are very disorganized and largely nonexistent. There are many benefits to local markets to growers, consumers, and communities for health, economic and sociological reasons. There is growing interest and support in local markets from community leaders, consumers, and growers. An organization originated from Loyola University, marketumbrella.org, has an excellent program to develop high quality farmers’ markets and work with market managers. After Hurricane Katrina, several organizations took an interest in South Mississippi and identified the lack of local food systems as a serious deficiency. Grants were given by the Kellogg Foundation and Ford Foundation to Mississippi State University (MSU) Extension, National Center for Appropriate Technology (NCAT), marketumbrella.org, the Ocean Springs Fresh Market, and the Moss Point Market to develop local food systems. MSU and NCAT's function was to develop growers. Three workshops were held to instruct growers on fruit and vegetable crop production and diversification, crop scheduling and season extension, marketing techniques and options, community development considerations, value added options, food safety, grading and handling, and postharvest practices. Growers became familiar with their production and marketing options and made decisions on the best marketing avenues for their farm. A number of the growers involved in the workshops have gone on to grow and sell at the various markets they learned about at the workshops. Several have developed value added products and all have improved their marketing techniques so they are more successful at marketing their products.
Fruit Crops Section
Virus Diseases of Blackberry and Raspberries
Robert R. Martin*1, Rose C. Gergerich2, James Susaimuthu3, and Ioannis E. Tzanetakis4, 1USDA-ARS Horticulture Crops Research Lab, Corvallis, OR; Department of Plant Pathology, University of Arkansas, Fayetteville, AR; Department of Plant Pathology, Cornell University, Cornell, NY; and Department of Molecular Biology, Oregon State University, Corvallis, OR
Two viruses have been associated with Blackberry yellow vein disease (BYVD). One of these viruses, Blackberry yellow vein associated virus (BYVaV) is a member of the genus Crinivirus and has been identified in blackberries exhibiting the BYVD in several states in the southeastern US. If consistent with known criniviruses, BYVaV should be transmitted by whiteflies, although this has not yet been demonstrated. A second virus, designated as Blackberry virus Y (BVY), is a member of the family Potyviridae, but lacks the signature DAG motif and therefore it likely will not be transmitted by aphids. It lacks several common features of the family and contains an alkB domain, suggesting it may represent a new genus in this virus family. The vector of this virus has not yet been determined, but eriophyid mites and aphids are being tested. In some cultivars of blackberry, these viruses in single infections do not cause symptoms. When both viruses are present, dramatic leaf symptoms and plant decline are observed. BVY has not been identified in all symptomatic plants, suggesting there may be other viruses that in combination with BYVaV are able to cause BYVD. In red raspberry, the possibility of a virus complex being responsible for severe crumbly fruit rather than single infections with Raspberry bushy dwarf virus (RBDV) is being investigated. Two viruses have been identified from red raspberry that exhibited a chlorotic leaf flecking and were free of RBDV. Based on partial sequence analysis, these viruses should be aphid transmitted. One of the viruses belongs to the genus Closterovirus and has been identified in raspberry material from Washington and Scotland. It has also been found in several isolates of raspberry leaf spot and raspberry leaf mottle from Scotland, suggesting it may be a component of the raspberry mosaic complex. Recent work with developing control strategies for Tomato ringspot virus and RBDV will also be presented
Toward the Perfect Blackberry in Cultivar Development
John R. Clark Department of Horticulture, 316 Plant Science, University of Arkansas, Fayetteville, AR 72701
Excellent progress has been made in the last 40+ years to improve quality, fruit size, productivity, plant adaptation, thornlessness, and other characteristics in cultivar options of southern blackberries. These improvements have contributed to expansion in blackberry production, initially for local and pick-your-own sales, and more recently in expanded retail marketing through shipping of fruit. Further expansion is occurring worldwide where blackberries can be grown and markets are available to sell the fruit profitably. Envisioning further improvement toward the “perfect” blackberry allows one to dream of what can be done to make this small fruit crop more desirable by consumers, marketers, and growers. The first area of focus toward perfection is on fruit quality, with an emphasis on sweeter berries. Soluble solids content of 10% or more is recognized by consumers to be much improved over that of wild berries or older cultivars. Flavor aspects such as reduced acidity levels and enhanced flavor components can further expand consumption. Other fruit quality characteristics such as reduced seediness, retention of black color, lack of berry leakiness, freedom from mold, and others can be improved further. Berry size and productivity continue to be areas of focus in breeding, and adequate variation exists for these traits to allow more advances to be made. Plant adaptation has become a more substantial issue as production expands to lower-chilling environments. Variation in chilling requirement plus the incorporation of the primocane fruiting trait will facilitate blackberry production expansion to occur with better adapted cultivars. This an exciting time for blackberries, and the road to “perfection” is unfolding in further cultivar improvement.
Evaluation of Blackberry Production Systems
Jim Pitts* and Robert Boozer, Auburn University, Chilton Research and Extension Center, 120 County Rd. 756, Clanton, AL 35045
Three trellis systems were evaluated for harvest efficiency, fruit yield and fruit quality for two blackberry varieties, ‘Apache’ (thornless type) and ‘Kiowa’ (thorny type). Results were recorded during the 2003-2006 harvest seasons. Trellis systems employed were freestanding, shift trellis (Stiles), and two-wire static trellis (Powell). Plant spacing was 2 feet in the row for the freestanding, and 4 ft in the row for the shift and two-wire static systems. Fruit were harvested two times per week. Fruit quality for ‘Kiowa’ was highest each season and harvest efficiency best 3 out of 4 years on the two-wire static trellis. Two years out of four, fruit yields of ‘Kiowi’ and net returns calculated per acre were highest for the shift trellis. ‘Apache’ did not perform well in this planting and berry size was not affected by trellis type.
Symptomology of Simulated Herbicide Drift Injury in Grape
Joseph G. Masabni*, University of Kentucky Research and Education Center, P.O. Box 469, Princeton, KY 42445
Grape is a crop on the rise in Kentucky, with 30 operating wineries. Growers choose ideal locations for grape production. However, these same locations are also best suited for corn, soybean, or hay production. In the last few years, a lot of vineyards have been established in the areas heavily invested in corn or soybean. Consequently, complaints of drift injury on grapes have been reported when neighboring fields are sprayed with early season preplant burndown herbicides. In order to teach grape and non-grape growers the potential of herbicide drift injury on grapes and the symptoms of injury of various herbicides, an experiment was conducted at the research station in Princeton, Ky. The experiment consisted of agronomic herbicides not labeled for grape, and of herbicides currently labeled on grape, sprayed directly on the foliage at 1/100X, 1/10X, and 1/2X rates to simulate drift injury. The X rate is the low end of the labeled rate range specified for each herbicide. The experiment was applied twice in 2006, on June 23 or mid-season, and on July 27 or late season. Results varied with various herbicides and ranged from complete desiccation with triclopyr to minor leaf yellowing with atrazine, to no injury. 2,4-D and dicamba, sprayed at lower rates ranging from 1/1000X to 1/100X, didn't show any injury symptoms typical of growth regulators. It is speculated that the grapevines are more tolerant to 2,4-D and dicamba drift damage in mid and late season. This experiment will be repeated in 2007 to evaluate 2,4-D injury potential at the budbreak stage.
Evaluation of 38 Peach Cultivars in Western Kentucky
Joseph G. Masabni* and Dwight Wolfe, University of Kentucky Research and Education Center, P.O. Box 469, Princeton, KY 42445
Cultivar choice is one of the most important decisions every fruit producer makes. Although cultivar performance and fruit quality information is very useful, obtaining this information is time consuming, due to the time required for fruit trees to start production. It is also expensive due to the large number of cultivars available. In 2004, a block of 37 peach cultivars was planted. The phenology of each cultivar was recorded in 2005 and 2006. Also recorded in 2006, was yield, fruit size, and percent soluble sugars or Brix. The top three yielding peach cultivars in 2006 were ‘Glowingstar’, ‘PF 20-007’, and ‘Laurol’, with 68.5, 56.9, and 56.4 lb/tree, respectively. These top yielders didn't have the largest fruit size at harvest. The largest fruit size was collected from ‘Encore,’ ‘John Boy II’, and ‘PF Lucky 21’ with 11.3, 6.9, and 5.7 oz/fruit, respectively. PF 5B and PF 1 ripened 30 days before ‘Redhaven’, and ‘PF Lucky 13’ ripened 7 days before ‘Redhaven’, while ‘Snow Brite’, ‘PF 15A’, ‘RedStar’, and ‘Summer Breeze’ ripened on the same date as the standard ‘Redhaven’. The latest-maturing cultivars Encore, Snow Giant, and Laurol were harvested as last as 21 Aug. or 5 weeks after ‘Redhaven’. Soluble sugars or Brix ranged from 8% to 12%, a difference not easily detected by the human palate.
Painting Your Way through Peach Culture
Kathryn C. Taylor1, Frank Funderburk2, and Wayne Mitchem3, 1Department of Horticulture, University of Georgia, Byron, GA 31008; 2Peach County, Cooperative Extension Service, University of Georgia, Fort Valley, GA 31030; 3Department of Horticultural Sciences, North Carolina State University, Raleigh, NC 27695
White exterior-grade paint, a common tool that can be implemented more widely and efficiently, was used for protection against herbicide damage to 1-year-old trees. Use of trunk painting is not a new idea for trunk protection from herbicides. Our intention was to determine if paint could be applied to young trees in bulk as a preplant preparation. Important to the viability of this technique is to determine what care must be taken to keep paint from some portions of the tree, for example, the roots or apical buds while placing paint on other portions of the tree, the trunk. Five paint treatments were implemented preplant: painting the entire tree, painting the trunk only, painting all but the roots, painting all but the apical buds or an unpainted control. Four herbicide treatments were used: flumioxazin, flumioxazin + crop oil, flumioxazin + paraquat, or paraquat. The best tree growth was observed in trees that received flumioxazin + crop oil treatment and paint treatments in which either the trunk only or all but the roots were painted. Poorest growth was observed when either the roots were painted or unpainted trees were exposed to either treatment including crop oil. The study indicates that bundles of trees may be inverted into paint up to the planting depth (not covering the roots with paint) as an inexpensive, efficient means of protection of the green bark from herbicide damage during the first year of culture.
Preliminary Assessment of Captan Impact on Fruit Finish
Kathryn C. Taylor1 and Phillip Brannen2, 1Department of Horticulture, University of Georgia, Byron, GA 31008; 2Department of Plant Pathology, University of Georgia, Athens, GA 30602
A conventional recommendation for peaches grown in the Southeast has been that the fruit should not receive captan applications within 30 days of harvest to avoid inking. In recent history, we have been pushing that recommendation to only 20 days before harvest to allow for the use of this material as a resistance management tool against the loss of dimethylation inhibiting fungicides. Additionally, during the recent past we determined that implementation of daily brush cleaning on packing lines, reduced the level of powdered pesticide formulations like captan, which tended to build up on packingline brushes, contaminating fruit with unduly high levels during packing. Because captan is a particularly abrasive material we tested the hypothesis that the primary source of captan injury was physical and exacerbated by brushing during fruit packing. Our study demonstrates that application of captan even within 4 days of harvest did not significantly increase inking when packed over clean packing line brushes. However, contamination of packing line brushes with captan or even application of captan in the wax without brushing caused substantial inking. Continued study is underway, as this study was conducted during a drought year. We may find that application close to harvest during a wet year or with overhead irrigation may contribute to inking.
Analysis of Long-term Pecan Tree Yields from Three Different Orchards Involving Numerous Varieties Using Mixed Model Analysis Techniques
Benjamin G. Mullinix* and Patrick Conner, University of Georgia Tifton Campus, Tifton, GA 31793-0748
Records from pecan trees have been maintained from 1919 through the present from two orchards and for several years for a third orchard. Data for the different years pertaining to an individual tree is influenced by the effect of Year and by correlated responses from year to year. When considering multiple trees for the same variety spread over numerous varieties covering better than seventy years, the task of sorting out where the variation in responses lies becomes daunting. Using mixed model analysis provides an answer to some of these problems. A transformation that is useful is to find the cumulative yield over the years for each tree. The total yield for each tree can be divided into each year's cumulative value to arrive at a growth function which begins at zero and ends with 100%. Also, cumulative yield can be transformed using log10. The yearly estimate across trees is a mean percentage increase in total yield. The estimate for each variety is the mean yearly increase in yield. Instead of working with estimates of means, part of the analysis will be reported as components of variance. Only varieties will be reported as estimates of mean effects.
The Blueberry Orchard Bee
Blair J. Sampson1,2, James H. Cane3, and Patricia R. Knight1, 1Mississippi State University, Coastal Research and Extension Center, 1815 Popps Ferry Road, Biloxi, MS 39532; 2USDA-ARS Thad Cochran Southern Horticultural Research Laboratory, 810 Hwy. 26 W., Poplarville, MS 39470; 3USDA-ARS Bee Biology and Systematics Laboratory, Logan, UT 84322-5310
Blueberry orchard bees prefer to forage at flowers identical to those of blueberries. There are other species of orchard bees and a few can be purchased as pollinators for apples, almonds, cherries, strawberries, and raspberries. However, these bees prefer other bloom sources to blueberry. Only the blueberry orchard bee has the instincts needed to be an effective and manageable blueberry pollinator. In fact, the bee does better feeding its offspring pollen and nectar from blueberry rather than from its own natural host plants (bearberries and barberries). Tests in Alabama and Mississippi show that females emerging as early as 1 Feb. and as late as 1 Apr. can pollinate blueberries cultivated from central Florida to North Carolina west to Louisiana and Texas. Each pollinating female visits as many as 10,000 blueberry flowers in her short 3-4 week lifespan and is responsible for setting about 12 kg of berries. Blueberries set by flowers pollinated by blue orchard bees are just as large and can be harvested as early as those resulting from pollination by southeastern blueberry bees, which are regarded as the most important native pollinators of southern blueberry crops. Orchard bees have the added advantage of being actively managed by blueberry growers. We discuss the history of our research program, bee propagation, and future efforts for commercially releasing the blueberry orchard bee.
Blueberry Splitting Tendencies as Effected by Fruit Firmness
Donna A. Marshall*, James M. Spiers, and Stephen J. Stringer, Thad Cochran Southern Horticultural Laboratory, Poplarville, MS
Understanding the cause of fruit splitting in blueberries is difficult. Researchers have been working on the problem of fruit splitting in various fruit crops for more than 70 years. If a few key factors that cause splitting in blueberries can be identified and these factors can be evaluated in new potential cultivars, then long-term reductions in commercial blueberry fruit splitting are feasible. Blueberry breeders strive to develop a blueberry that is firm in texture. Yet, in previous studies splitting-susceptible fruit had higher fruit firmness values than splitting-resistant varieties. This study was initiated to further investigate the correlation between splitting susceptibility and fruit firmness. Rabbiteye (Vaccinium ashei) and southern highbush (Vaccinium corymbosum X) blueberry cultivars and selections were used to determine if berries with higher measurements of fruit firmness had a higher splitting occurrence. Berries were measured for fruit firmness using a QTS25 and/or a FirmTech2 instrument. Fruit were submitted to laboratory-induced splitting. Correlations were determined by SAS. A significant negative correlation was found between splitting and deformation values tested on QTS25. No other significant correlation was found between splitting and firmness measurements.
The Influence of Nitrogen Rate on Pecan Kernel Necrosis, Leaf N Concentration, Yield, and Nut Quality
Michael W. Smith*, Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK 74078
Pecan [Carya illinoinensis (Wangenh.) C. Koch] kernels (cotyledon) of ‘Pawnee’ displayed a consistent malady not described previously that was designated as “kernel necrosis.” The severest form of the problem was blackened, necrotic tissue engulfing the basal one-half to one-third of the kernel. The mildest form was darkened tissue in the dorsal grove at the basal end of the kernel. The problem was first observable during the gel stage of kernel development. No symptoms of kernel necrosis were visible on the shuck (involucre). Soil concentrations of nitrate were unusually high in the soil profile during January. Groundwater used for irrigation was contaminated with 34 mg·L−1 NO3-N. An experiment evaluated three nitrogen (N) rates, 0, 0.8 g·cm2 cross-sectional trunk area applied in March, and the producer's current N rate of 1.6 g + 1.6 g + 1.2 g·cm2 cross-sectional trunk area N applied during the second week in March, first week in June, and first week in September, respectively, on the incidence of kernel necrosis, leaf N concentration, soil NO3 concentration, yield, nut quality, and growth over five years. Nitrogen received in the irrigation water by all trees was 142, 191, 127, and 147 kg·ha−1 N in 2002 through 2005, respectively, as NO3 from the groundwater. Leaf N was affected by treatment only once during the study. Nitrates accumulated in the soil, increasing 24% in three years when no supplemental N was applied, except in the contaminated irrigation water. Kernel necrosis was either not affected by N treatment or during one year kernel necrosis was highest without supplemental N application. Tree yield, kernel quality, and growth were not affected by N treatment. Alternate bearing was apparent, suggesting that abundant N will not alleviate this problem. Kernel necrosis is a severe problem in this orchard, and has been identified in several orchards at low frequencies. The cause of kernel necrosis remains unknown.
Floriculture, Ornamentals, and Turf Section
Adopt-A-Tree: A Reforestation Program to Replace Lost Urban Canopy due to Disasters
Adrian G.B. Hunsberger, University of Florida/IFAS Miami-Dade County Extension, 18710 SW 288th Street, Homestead, FL 33030
Miami–Dade County Florida has an average tree canopy cover of less than 10%, compared to the national average of over 30%, with some areas having only 2% canopy cover. This low tree canopy coverage is due in part to losing one-half million backyard trees to the Citrus Canker Eradication Program. Countless additional trees have been lost from hurricanes and floods. To help replace lost tree canopy, Miami-Dade county applied and received a $6,000,000 grant which was used to create the “Adopt-A-Tree” Program. This allows Miami-Dade County homeowners to “adopt” two high quality locally grown trees per year. Tree adoption events are held throughout the county, with priority given to areas with the poorest tree canopy. University of Florida/IFAS Miami–Dade County Extension faculty provided input on program development and horticultural advice, conducted grades and standards workshops for nursery growers, developed bilingual (English and Spanish) educational materials, and staffed “adoption” events. As part of the “adoption” process, homeowners must attend an educational component before receiving trees. This includes a hands-on demonstration of correct planting procedures, which is important for our very shallow soils. Extension's educational materials are distributed to participants as part of the “adoption” process. During the past five years, over 120,000 people have been taught basic tree care; over 100,000 trees have been distributed at “adoption” events. Fruit trees are the most popular and non-flowering native trees the least popular. Program participants were surveyed 1 to 2 years post-adoption. An average of 79.2% trees survived, 96% of participants stated that the program met or exceeded their expectations, and 94% said that the educational materials were useful. In addition to the main goal of reforesting the county, this program has produced several additional effects: increased public awareness of the Extension as an educational resource, improved quality of nursery trees, and increased knowledge of proper tree care. The number of trees to be distributed will eventually total 184,000 and is by far the largest urban reforestation project of its kind in Florida.
Growth and Production of Ginger Lilies under a Sustainable Agroforestry System with Moringa in the U.S. Virgin Islands
Ramon A. Arancibia*1, Manuel Palada1, Mack Thetford2, and Shibu Jose2, 1University of the Virgin Islands–Agricultural Experiment Station, St Croix, VI 00850; 2University of Florida–West Florida Research and Education Center, Milton, FL 32583
Growth and production of ginger lilies (Alpinia purpurata) were evaluated in an alley cropping system with moringa (Moringa oleifera) in the U.S. Virgin Islands. Ginger lilies were planted on 1 June 2005 as monoculture and in alleys (5 m wide) between rows of moringa trees (5 years old). The spacing was 0.9 m in row and 1.7 m between rows with two rows of ginger lilies in the alleys. Plot length was 10 m. Plots were divided in two subplots with and without fertilization (30 kg·ha-1 weekly of 20-20-20). In addition, moringa trees were partially pruned every 3 to 4 months and the biomass (foliage) was used as green manure for the alley crop. Nitrate concentration in the sheath sap was 448 and 150 ppm in the fertilized subplots and non-fertilized, respectively. In contrast, nitrate and potassium concentrations were the same in full sun and alley suggesting that moringa biomass was not sufficient to increase the nutrient status of the crop. Shade from moringa trees reduced solar radiation in the alley plots to 29% of that in full sun that resulted in reduced growth and number of floral spikes. Flowering started 6 and 10 months after planting in the monoculture and the alley, respectively, but harvest of commercial quality spikes was obtained after 13 months. In this first season of production (July to Dec. 2006), 31, 19, 10, and 3 flowers per plant were harvested in the fertilized monoculture, non-fertilized monoculture, fertilized alley, and non-fertilized alley, respectively. Production under a sustainable agroforestry system, although lower due to the shady conditions, is still a viable option to increase production and value of marginal forest areas.
The Impact of Foliage Container Garden Sales on Identifying Consumer Needs, Trends, and Preferences
Emily Stefanski*1 and James L. Gibson2, 1Department of Environmental Horticulture, University of Florida, 1545 Fifield Hall, Gainesville, FL 32611; 2Department of Environmental Horticulture, University of Florida–Milton, 5988 Highway 90, Milton, FL 32583
Retail garden center sales in Florida have increased from $5.1 billion in 2000 to $6.9 billion in 2005, with container garden sales being an economically important component of this trend. Florida is a state recognized for its wholesale production of foliage plants. In 2005, foliage plants represented $476 million of the total $976 million in total sales of floriculture crops. Identifying new marketing strategies and generating consumer data are important goals to improve foliage plant sales, therefore the objective of our study was to measure retail consumer preferences of foliage plant container gardens. In the fall of 2006 three types of foliage plant container gardens in green or terra cotta-colored, 25 × 25-cm pots displayed in three retail areas of a plant sale. Locations included the landing zone (before the entrance), transition zone (from entrance to inside), and the destination zone (within the retail setting). Consumer preferences and demographics were measured using a post-purchase survey. Results indicated more container gardens were purchased from middle-class females who were novice gardeners who frequently purchased plant material. More container gardens were purchased when displayed near the entrance. Container color had little impact on consumer preference, with more interest in high-quality foliage plant container gardens with unique color combinations.
Infectivity of Mycorrhizal Products Marketed for Trees in Urban and Landscape Soils
P. Eric Wiseman*1 and Christina E. Wells2, 1228 Cheatham Hall, Department of Forestry, Virginia Tech, Blacksburg, VA 24061; 2151 Poole Agriculture Center, Department of Horticulture, Clemson University, Clemson, SC 29634
Commercial products containing propagules of arbuscular mycorrhizal fungi (AMF) are widely marketed to improve woody plant performance on urban and landscape soils. The infectivity of commercial mycorrhizal inoculants has rarely been subjected to independent testing. Over a 3-year period, commercial mycorrhizal inoculants were evaluated in a series of greenhouse experiments using corn (Zea mays), sorghum (Sorghum bicolor), trident maple (Acer buergerianum), and sweetbay magnolia (Magnolia virginiana) as host plants. In corn and sorghum, colonization rarely exceeded 5% when plants were treated with anonymously purchased products. In contrast, a lab-cultured inoculant of similar composition yielded mean colonization of 38% to 61%. Despite the near absence of colonization, commercial AMF products generally improved shoot growth and increased soil concentrations of phosphorus, potassium, calcium, and magnesium in a dose-dependent manner. Commercial AMF products did not increase mycorrhizal colonization or shoot growth in magnolia or maple saplings. In a subsequent experiment, product-treated magnolia seedlings developed little or no mycorrhizal colonization, whereas plants treated with a lab-cultured inoculant were 74% colonized. If commercial AMF products are to receive broad acceptance as amendments for urban soils, manufacturers must better demonstrate that their products are compatible with current retail distribution methods and can promote mycorrhizal colonization under the conditions of their intended use.
Effects of Vernalization and Photoperiod on Growth and Flowering of Three Coreopsis Cultivars
J. Raymond Kessler* and Gary J.Keever, 101 Funchess Hall, Department of Horticulture, Auburn University, AL 36849
Coreopsis grandiflora ‘Early Sunrise’ and ‘Baby Sun’ and Coreopsis lanceolata ‘Sterntaler’ plants were treated with 0, 2, 4, 6, or 8 weeks of vernalization (VER) at 4.4 °C and then placed in a greenhouse under either natural photoperiods (NAT) beginning in November or night-interrupted lighting (NIL) . ‘Baby Sun’ flowered 100% under NAT and NIL, indicating that VER was not required for flowering. NIL reduced DTF compared to NAT indicating that the response to photoperiod in this cultivar is quantitative. ‘Sterntaler’ flowered 100% after 4–8 weeks of VER; however, none of the plants flowered after 0–2 weeks of VER, indicating a qualitative requirement for at least 4 weeks of VER for flowering. NIL reduced DTF compared to NAT, indicating that the response to photoperiod in this cultivar is also quantitative. ‘Early Sunrise’ flowered 100% after 4–8 weeks of VER. None of the plants flowered after 0-2 weeks of VER, except those receiving 2 weeks VER under NIL that flowered 50%. Because 50% flowering would not be acceptable in practical application, the VER requirement for ‘Early Sunrise’ may be considered qualitative requiring at least 4 weeks of VER for flowering. NIL did reduce DTF compared to NAT. Therefore, the response to photoperiod in this cultivar is quantitative.
Biology and Control of the Strawberry Rootworm in Container-grown Ornamental Crops
Charles Hesselein*1 and David Boyd2, 1Mobile Ornamental Horticulture Research Center, PO Box 8276, Mobile, AL 36689-0276; 2USDA-ARS Southern Horticultural Laboratory, P.O. Box 287, Poplarville, MS 39470
Several systemic insecticides, Safari (12 and 24 oz), Celero (5.6 and 11.3 oz), Flagship (0.2 oz), Marathon II (21.8 fl oz), and Discus (120.3 and 167.7 fl oz), along with the non-systemic insecticide Talstar (10 and 40 fl oz) were applied as drenches to 1-gal potted ‘Pink Pear’ azalea plants for control of a leaf-feeding beetle, the strawberry rootworm (Paria fragariae). (Rates, in parentheses, are amount of product per 100 gal.) Multi-branched cuttings were removed from these plants in the field, beetles were placed on those cuttings and treatments were evaluated in the laboratory 8, 28, 56, 106, and 173 days after treatment (DAT). Treatments were evaluated both by counting living and dead beetles and a visual rating of damage caused by foliar feeding at least 6 days after exposing beetles to treated foliage. Eight DAT, only the 24-oz Safari and 11.3-oz Celero treatments had more dead beetles than the control (2 and 2.8 dead of three beetles respectively, 0.3 for the control). Twenty-eight DAT, the Safari, Celero, Marathon II, and Discus treatments had more dead beetles than the control (50%, 63%, 67%, 100%, 100%, and 100% of recovered beetles dead, respectively, 8% for the control). On this date, the 12-oz Safari treatment was less effective than the Marathon II and both Discus treatments. Only the 24-oz Safari treatment had more dead beetles than the control 173 DAT (38% of recovered beetles dead, 8% for the control). Differences were noted among treatments for damage rating on all dates. Eight and 28 DAT, treatments containing Safari, Celero, Marathon II, and Discus had lower ratings than the control. Treatments containing Safari, Marathon II, and Discus had lower foliar damage ratings than the control 56 DAT, with Marathon II and Discus having lower ratings than Safari. On 106 and 173 DAT, Marathon II had lower foliar damage ratings than the control. It appears that the dose response for feeding cessation (i.e., damage) may be lower than that required to kill beetles. Due to the expense of drench-applied treatments, it is likely that only Marathon II, Discus, and possibly Safari drenches are practical for growers to use for control of the strawberry rootworm. More work needs to be done to determine the efficacy of spray treatments and the effect of drench treatments on media dwelling larvae.
Irradiation of Lagerstroemia to Induce Sterility
David Knauft* and Michael Dirr, Horticulture Department, University of Georgia, Athens, GA 30602-7273
Half-sib seed populations from two Lagerstroemia cultivars released by the University of Georgia breeding program, ‘Cherry Dazzle’ and ‘White Chocolate,’ and from one breeding line designated DWF 07-00 were treated with gamma radiation at 0, 15, 20, 30, and 40 kr. The treatments were imposed to induce sterility, with the goal of eliminating unattractive seed capsules from the plant, potentially increasing flowering duration, and providing an example of proactive research designed to address invasiveness in horticultural plants. Seed treated with the 30 and 40 kr dosages germinated but failed to survive past the cotyledonary leaf stage. The 15 kr dosage provided the largest number of viable seed in all three populations. At least 55% of the plants from all treatment combinations produced flowers the first year from seed. In one population of DWF 07-00 30% of the plants from 15 and 20 kr irradiation produced flowering plants without seed the first year of the study. In the second year, however, 85% of those plants produced at least some seed, suggesting physiological immaturity the first year from seed. Correlation of days to first flower between the first and second years were nonsignificant. None of the sterile plants have sufficient horticultural merit to be considered for cultivar release. While most of the sterile or low seed-set plants did not exhibit long flowering duration, several selections produced flowers for more than 150 days and are being used in breeding efforts.
Field Evaluation of Palms in Hardiness Zones 7b and 6b
Gary L. Wade, Department of Horticulture, 221 Hoke Smith Building, University of Georgia, Athens, GA 30602-7273
The purpose of this study is to evaluate selected palm species for their hardiness and adaptability to hardiness zones 7b and 6b. A replicated field planting of eight palms was established at a Watkinsville, Ga., research station, hardiness zone 7b, on 29 Apr. 2004. Palms planted were needle palm (Rhapidophyllum hystrix), dwarf palmetto (Sabal minor), Birmingham sabal (Sabal ‘Birmingham’), Brazoria palm (Sabal ×texensis), Louisiana dwarf palmetto (Sabal minor ‘Louisiana’), cabbage palm (Sabal palmetto), Kumaon palm (Trachycarpus takil), and windmill palm (Trachycarpus fortunei). On 23 June 2005, a replicated field planting of seven palms was established at research in Blairsville, Ga., hardiness zone 6b. Palms planted at this location were needle palm (Rhapidophyllum hystrx), Bulgarian windmill palm (Trachycarpus fortunei) (seed collected in Bulgaria), Taylor form windmill palm (Trachycarpus fortunei) (seed collected from palms in Raleigh, N.C.), McCurtain County dwarf palmetto (Sabal minor (seed collected from palms in McCurtain Co., Okla.), Louisiana dwarf palmetto (Sabal minor ‘Louisiana’), Birmingham sabal (Sabal ‘Birmingham’), and Brazoria palm (Sabal ×texensis). Growth measurements and cold damage assessment will be done over a 5-year period. The palms in the Blairsville study were provided cold protection their first year by enclosing them in wire hoops filled one-third full with dry pine straw and covered with 3-mil white plastic. No cold protection was provided to the Wakinsville palms. At the Watkinsville location, two Sabal palmettos and one Sabal minor ‘Louisiana’ died during the first winter. No additional palms have been lost since the first winter, and all remaining palms, with the exception of Rhapidophyllum hystrix, have shown significant growth increases over 2 years. At the Blairsville site, Sabal minor ‘Louisiana’ showed the greatest growth increase the first year (62%), Raphidophyllum hystrix showed no growth increase the first year, while the other palms grew an average of 20% during the first year. None of the palms in the Blairsville study died during the first winter. However, some of the species at that location have shown significant frond damage after several nights of single-digit temperatures during the winter of 2006–2007.
Final Summary of All-America Daylily Evaluations: Rust Observations, Flowering, and Landscape Performance
Allen D. Owings*1, Gordon E. Holcomb2, C. Allen Broyles3, Ann L. Gray1, and Edward W. Bush1, 1128 J. C. Miller Hall, Department of Horticulture, Louisiana State University Agricultural Center, Baton Rouge, LA 70803; 2444 Life Sciences Building, Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803; 34560 Essen Lane, Burden Center, Louisiana State University, Baton Rouge, LA 70809
All-America daylily cultivars have been evaluated in LSU AgCenter landscape trials from 2003–2006 to determine susceptibility to daylily rust (Puccinia hemerocallidis), flowering performance and overall visual quality. Individual plants of ‘Bitsy’, ‘Starstruck’, ‘Black Eyed Stella’, ‘Lullaby Baby’, ‘Judith’, ‘Bitsy’, ‘Leebea Orange Crush’, ‘Frankly Scarlet’, ‘Plum Perfect’, ‘Chorus Line’, ‘Lady Lucille’, ‘Miss Mary Mary’, and ‘Red Volunteer’ were placed in full sun rows of Olivier silt loam soil. Plants were ranged in a replicated completely randomized design and mulched with pine straw mulch twice annually. Plants were drip irrigated as needed to prevent stress. Slow-release fertilizer was applied twice annually—once in the spring at 1 lb N/1000 sq ft and once in the summer at half the spring rate. Fungicides were not applied during the study. Plants were rated for daylily rust presence annually in September and November. Plants were rated weekly from March through October annually for flower and bud presence. Resistant cultivars were ‘Miss Mary Mary’, ‘Chorus Line’, ‘Lullaby Baby’, and ‘Bitsy’. Slightly susceptible cultivars were ‘Black Eyed Stella’ and ‘Frankly Scarlet’. ‘Plum Perfect’ was moderately susceptible. Highly susceptible cultivars were ‘Red Volunteer’, ‘Lady Lucille’, ‘Starstruck’, ‘Leebea Orange Crush’, and ‘Judith’. Cultivars in bloom the most days were ‘Miss Mary Mary’, ‘Lady Lucille’, ‘Bitsy’, and ‘Black Eyed Stella’. The earliest to bloom cultivars were ‘Bitsy’, ‘Black Eyed Stella’, ‘Judith and ‘Miss Mary Mary’. Repeat bloomers were ‘Lady Lucille’, ‘Bitsy’, and ‘Black Eyed Stella’.
Initial Landscape Shrub Rose Observations: ‘Knock Out’, ‘Home Run’, ‘Wild Thing’, and ‘Nearly Wild’
Allen D. Owings*1, C. Allen Broyles2, and Ann L. Gray1, 1128 J. C. Miller Hall, Department of Horticulture, Louisiana State University Agricultural Center, Baton Rouge, LA 70803; 24560 Essen Lane, Burden Center, Louisiana State University, Baton Rouge, LA 70809
A landscape evaluation of shrub rose cultivars was conducted at Burden Center in Baton Rouge, LA, in 2006. Rose cultivars compared for overall performance and blackspot susceptibility were ‘Knock Out’ (Conard-Pyle, 2000), ‘Home Run’ (Weeks, 2006), and ‘Nearly Wild’ (Jackson and Perkins, 2007). A control cultivar, ‘Nearly Wild’, was included for comparison. No. 1 grade bushes were planted on 4-ft centers in April in raised 48-inch rows composed of Olivier silt loam soil. The planting location was full sun. Drip irrigation was provided as needed to prevent stress. Pine straw mulch was added at planting. Slow-release fertilizer was applied at the rate of 1.5 lbs N/1000 sq ft in April and at 1 lb N/1000 sq ft in July. Fungicide was not applied and pruning was not conducted. Visual quality ratings based on a scale from 1 to 5 were taken twice monthly June through October. Blackspot disease ratings were taken in August and October. Blackspot was not observed on ‘Knock Out’ or ‘Home Run’. Minor blackspot was noted on ‘Nearly Wild’ and ‘Wild Thing’ with ‘Nearly Wild’ having approximately 20% of foliage with blackspot and ‘Wild Thing’ having approximately 10% of foliage with blackspot by October. Visual quality was highest for ‘Knock Out’. ‘Home Run’ had quality ratings slightly less than ‘Knock Out’ but greater than the other two cultivars. In some months, ‘Home Run’ and ‘Knock Out’ were not significantly different in terms of plant quality. ‘Nearly Wild’ and ‘Wild Thing’ had the lowest visual quality ratings over the evaluation period.
Postharvest/Plant Biotechnology Section—Breeding vs. Molecular Approaches
Improving Shelf Life of Blackberries through Conventional Breeding
John R. Clark*1 and Penelope Perkins-Veazie2, 1Department of Horticulture, University of Arkansas, 316 Plant Science, Fayetteville, AR 72701; 2South Central Agricultural Research Lab, USDA–ARS, P.O. Box 159, Hwy. 3 West, Lane, OK 74555
The University of Arkansas began blackberry breeding in 1964, and fruit breeder James N. Moore envisioned vast improvement of this “native” southern U.S. crop through crossing and selection of existing germplasm. He used the recurrent mass selection system of breeding, a system that utilizes the crossing of complementary parents that show positive phenotypic traits, and selecting the superior progeny at fruiting. Great advances were made, and by 1983 four cultivars had been released that were superior to previous developments. The release of ‘Navaho’ in 1989 was a hallmark achievement in that it had erect, thornless canes, the first cultivar to exhibit this combination of traits. ‘Navaho’ was also identified to have much better shelf life than thorny cultivars, and in the early 1990s the interest for a cultivar that had shelf life for more than 1 to 3 days was developing, as pre-picked sales (rather than pick-your-own) were becoming more common. This led to the development of a cooperative research endeavor between the University of Arkansas (John R. Clark) and USDA-ARS (Penelope Perkins-Veazie) to expand postharvest evaluations of blackberries. Early progress indicated that: 1) ‘Navaho’ could be stored for up to 2 weeks in appropriate conditions; 2) firmness in field evaluations did not always translate to good shelf life; 3) substantial variability for shelf life was present in the Arkansas breeding germplasm; and 4) a protocol for routine evaluations could be developed to screen a wide range of genotypes, including evaluations for berry firmness, leakiness, development of mold, and retention of black drupelet color. This effort has led to expanded recommendations of commercial potential of newer cultivars such as ‘Apache’ and ‘Ouachita’ for the shipping market. Identification of superior parents for shelf life potential has led to hybridizations for improved shelf life to be undertaken with substantial further phenotypic advances identified. The relationship of breeder and postharvest physiologist in this effort has allowed substantial advances in technology for producers, resulting in major expansions of blackberry production in the South, other regions of the United States, and other countries.
Carotenoid Analysis using the Puree Absorbance Method for Germplasm Screening
Angela R. Davis*1, Wayne W. Fish1, Penelope Perkins-Veazie1, Amnon Levi2, and Stephen King3, 1South Central Agricultural Research Lab, USDA-ARS, P.O. Box 159, OK 74555; 2US Vegetable Laboratory, USDA-ARS, Charleston, SC; 3VFIC, Texas A&M University, College Station, TX
Many fruits and vegetables contain health-promoting compounds that can only be detected using labor-intensive methods. This is the case with quantifying carotenoids in fresh fruits and vegetables. Carotenoid content can vary significantly between varieties; therefore a method to rapidly screen germplasm for high carotenoid levels is desirable. Many laboratories have attempted to develop reflectance colorimetric methods to determine carotenoid content with varying degrees of success. Attempts to use reflective colorimetric values to estimate lycopene content in watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) have not been successful. To avoid the inherent problems with reflective color readings on the surface of cut watermelon, our group has successfully utilized a xenon flash spectrophotometer to measure absorbance of opaque purees of watermelon flesh. This absorbance can then be used to estimate total lycopene content in red fruit and total carotenoid content in canary yellow-fleshed watermelons. We have shown that our puree absorbance method also works well for estimating lycopene in fresh tomato purees and many processed tomato products. Preliminary results suggest that this method will also work for beta-carotene in cantaloupe and prolycopene in orange watermelon. The R2 values using this method compare well with other published methods, with ranges between 0.88 and 0.99 depending on the type of fruit and carotenoid being evaluated. The puree absorbance method is fast, accurate, requires no hazardous solvents, and yields values comparable with other analytical methods.
Pre- and Postharvest Effects on Bioactive Components and Human Health
Bhimanagouda S. Patil*, Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, 2119, Texas A&M University, 1500 Research Parkway Suite A120, College Station, TX 77845
Research during the last decade suggests that bioactive compounds in fruits and vegetables provide health-maintaining properties for cancer prevention and the health of the heart, brain, and eye. Citrus contains several bioactive compounds, such as carotenoids, flavonoids, furocoumarins, vitamin C, and folate. During the last 5 years, our results provided evidence that pre- and postharvest factors play a major role in altering the levels of bioactive compounds. Preharvest factors, such as genetics, harvest stage, and growing location, significantly affect lycopene concentrations in rio red grapefruit. While certain postharvest factors, such as storage temperature, significantly reduced vitamin C concentrations in rio red grapefruit, other citrus bioactive compound levels either maintained stability and/or increased. Other postharvest factors, such as irradiation, e-beam, and ultra-low oxygen storage, significantly affect certain specific bioactive compounds. This project is based upon work supported by the USDA-CSREES IFAFS#2001-52102-02294 and USDA-CSREES#2005-34402-14401, “Designing Foods for Health” through the Vegetable and Fruit Improvement Center.
Microarray Analysis: Uses and Limitations
Patrick Wechter*1, Amnon Levi1, Daniel Kluepfel2, and Gernot Presting3, 1USDA-ARS, US Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414; 2USDA-ARS, Crops Pathology and Genetic Resource Unit, 378 Hutchison Hall, Davis, CA 95616; 3Department of Molecular Bioscience and Bioengineering, 1955 East-West Road, Ag. Science #218, University of Hawaii–Manoa, Honolulu, HI 96822
The use of microarray technology has exploded in recent years. All areas of biological research have found application for this powerful platform. From human disease studies to microbial detection systems, a plethora of uses for this technology are currently in place with new uses being developed continuously. Although an extremely powerful technology, certain limitations do exist. These limitations include sensitivity, false discovery, and cost. Some current uses of microarrays in agriculture include gene expression studies, microbial identification, transcription factor profiling, and comparative genome sequencing. Several projects in our laboratory utilize high-density microarrays. In one of these studies we are investigating the global, genetic regulation of a biocontrol bacterium during interaction with a host plant's rhizosphere. This study has identified more than 300 up-regulated and down-regulated genes that appear to be modulated in/by the rhizosphere. Transposon-based gene-knock-out studies and quantitative-PCR have confirmed the microarray results for several of these genes. In a second study, we have used a bioinformatics-based approach to develop microarrays for use in identifying targeted soilborne bacteria. This proof of concept approach allowed us to identify specific bacteria at levels of less than 1 × 103 cells/gram of soil using high-density photolithography arrays.
Analysis of Genes Expressed during the Development and Ripening of Watermelon Fruit
W.P. Wechter1, A. Levi*1, A. Davis2, Z. Fei3, A. Hernandez4, J. Thimmapuram4, P. Dang5, N. Katzir6, K. Tadmor6, and J. Giovannoni7, 1USDA-ARS, US Vegetable Laboratory, 2700 Savannah Hwy., Charleston, SC 29414; 2USDA-ARS, South Central Agricultural Research Laboratory, Hwy. 3 West, Lane, OK 74555; 3Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY 14853; 4University of Illinois, W.M. Keck Center for Comparative and Functional Genomics, 340 Edward R. Madigan Laboratory, 1201 West Gregory Drive, Urbana, IL 61801; 5USDA, ARS, NPRL, 1011 Forrester Dr., SE, P.O. Box 509, Dawson, GA 39842-0509; 6Agricultural Research Organization (ARO), Newe Yaar Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel; 7USDA-ARS, US Plant, Soil and Nutrition Laboratory, Tower Road, Cornell University, Ithaca, NY 14853
A cDNA library was constructed from mRNA isolated at three distinct developmental stages (12, 24, and 36 days post-pollination) from watermelon flesh of the heirloom cultivar Illiniwake Red. The library was first normalized and then subtracted by hybridization with leaf cDNAs. Random cDNA clones (8832) of the watermelon flesh subtraction library were sequenced from the 5’ end in order to identify potentially informative genes associated with fruit setting, development, and ripening. The 8832 expressed sequence tags (ESTs) produced 4719 non-redundant sequences “EST-unigenes.” BLAST analysis revealed 1269 EST-unigenes (≈27%) that have no significant homology to sequences published so far for other plant species. The BLAST analysis revealed “EST-unigenes” associated with metabolism, membrane transport, cell wall formation and cell division, signal transduction, nucleic acid binding and transcription factors, defense and stress response, and secondary metabolism. Microarray analysis for 832 EST-unigenes identified 174 ESTs that are up-regulated and 161 ESTs that are down-regulated during fruit development and ripening. This study provides an expanded pool of genes that can be useful targets in future genetic and functional genomic studies of watermelon fruit.
Vegetable Crops Section
Determining Ideal Planting Densities for Broccoli Production in Georgia
William Terry Kelley* and Denne Bertrand, Department of Horticulture, University of Georgia, 4604 Research Way, P.O. Box 748, Tifton, GA 31793
Because of increasing transportation costs, broccoli production in Georgia is becoming economically feasible. Georgia has for years recommended a plant spacing of 12 inches between plants in rows 36 inches apart. However, this spacing does not seem to produce the best yields or quality that would make broccoli most profitable for Georgia growers. The objective of this work was to evaluate the effects of various plant populations on broccoli yield and quality in Georgia. Broccoli was planted at in-row spacings of 6, 9, and 12 inches in rows that were both 36 and 18 inches apart. These arrangements produced populations that ranged from 14,520 to 58,080 plants per acre. Plots were 12 ft long and were replicated four times in a randomized complete-block design. ‘Gypsy’ hybrid broccoli was transplanted to the field on 3 Mar. and 8 Sept. 2006. Spring harvests occurred between 4 May and 8 June and fall harvests between 4 Dec. 2006 and 2 Jan. 2007. Yield, stem diameter, and head diameter were measured for all plots. Other than spacing, normal cultural practices were employed. Spring yields were significantly greater with the highest populations and decreased almost linearly to the lowest population. There were no significant differences in fall yields, although the two highest populations produced numerically higher yields than the others. Stem size was quite variable among treatments in the spring, but the higher populations produced smaller stems and heads in the fall test. Higher populations than currently recommended seem to be justified.
Success Seen in Certified Organic Summer Squash Production in Mississippi
William B. Evans*, Peter M. Hudson, and Keri L. Paridon, Mississippi State University, Truck Crops Branch, Crystal Springs, MS 39059-0231
A multi-year study is being conducted at Crystal Springs, Miss., to determine the yield, crop quality, and economic returns from organic vegetable crop production. The study site contains two growing areas, a field managed as a certified organic system (ORG), and another non-adjacent field area containing the same crops and rotation, but managed predominantly with local standard practices (STND). Both systems employed drip irrigation but not polyethylene mulch. Relative to yield and quality produced in the STND plots, several vegetable species have been produced successfully within the ORG plots, including summer squash (Cucurbita pepo). In 2006, two squash cultivars, zucchini ‘Black Beauty’ (BB), and yellow straightneck ‘Early Prolific Straightneck’ (EPS), were evaluated as early summer crops. In April, greenhouse-grown seedlings were transplanted 24 inches apart into field plots 20 ft long, with rows 42 inches apart. Beginning in late May, plots were harvested two or three times each week for 6 weeks. ORG BB total yield (lbs/plot) (standard deviation, n = 4) was 26 (2.6); STND was 48 (2.5). ORG EPS total yield was 28 (7.9); STND was 29 (2.2). ORG BB marketable yield was 23 (6.0); STND 24 (3.7). ORG EPS marketable yield was 19 (26). ORG BB percent marketable yield was 73 (4.0); STND was 56 (9.4). ORG EPS percent marketable yield (%) was 83 (4.3); STND was 84 (6.7). Mean fruit size was also similar within cultivars, between systems.
Ripeness Determination in Personal-sized Seedless Watermelons: Preliminary Results
Edgar L. Vinson, III*1, Joseph M. Kemble1, Floyd M. Woods1, Wheeler G. Foshee, III1, and Jason E. Burkett2, 1101 Funchess Hall, Department of Horticulture, Auburn University, Auburn, AL 36849; 2E.V. Smith Research Center, Horticulture Unit, Shorter, AL
External physiological changes in ‘Valdoria’ and ‘Vanessa’ personal-sized watermelons such as number of proximally located senescent tendrils, fruit weight, fruit circumference, and groundspot color change were observed to determine their efficacy in signaling adequate (≥10%) soluble solids (SS) readings. Soluble solids readings are the primary means of determining ripeness in watermelons. Flowers were tagged at anthesis then fruit were harvested at 20, 30, 40, and 50 days after anthesis (DAA); then data were collected. Regression and correlation analyses were conducted between SS and each of the following: number of senescent tendrils, fruit weight, fruit circumference, and groundspot color changes. The growth indices, weight (r2 = 0.72) and circumference (r2 = 0.53) were positively correlated with SS. Numbers of senescent tendrils were also correlated with SS (r2 = 0.51), although not as strongly. Groundspot color change was not correlated with SS in this study. Watermelons in this study reached 10% SS at approximately 30 DAA and SS continued to rise until 40 DAA; however, by 40 DAA watermelons were overripe, based on texture of fruit flesh and development of off-colors. Future steps in this study will include other internal means of determining ripeness such as pH, titratable acidity, and lycopene content.
TYLCV-resistant Tomato Variety Trial
Kent E. Cushman* and Philip A. Stansly, 2686 SR 29 N, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL 34142
Yields of tomato in central and southern Florida can be greatly impacted by tomato yellow leaf curl virus (TYLCV) vectored by Bemisia tabaci (silverleaf whitefly). Management of whitefly populations and reducing inoculum through sanitation practices and roguing are means of controlling the disease. TYLCV-resistance is an underused strategy because varieties thus far developed are often deemed unacceptable due to perceived imperfections such as small fruit size, susceptibility to other diseases, and poor shipping quality. The objective of the present trial was to evaluate horticultural qualities of 12 presumably TYLCV-resistant genotypes grown in a trial with three replications during the winter-to-spring 2006 growing season at the Southwest Florida Research and Education Center in Immokalee. Horticultural characteristics and disease incidence of these 12 entries were compared to that of a standard TYLCV-susceptible cultivar, ‘Florida 47’. Whitefly populations were low until after first harvest and disease incidence was low throughout the duration of the study. ‘Florida 47’ and two additional entries, ACR-242 and ACR-2012, exhibited disease incidences of 5% to 8%, indicating the control and these entries were not resistant genotypes. Symptoms of TYLCV were not observed among the other entries. HA 3075 was the only entry to produce significantly greater total yield than ‘Florida 47’ though its total yield was not significantly different from that of S-50257, VT-60774, and VT-60780. HA 3075 also produced the highest yield of extra-large fruit, though not significantly different from that of ‘Florida 47’. Average fruit weight in this size category was highest for BHN 745 at 9.4 oz/fruit, similar to that of ‘Florida 47’ and ‘Tygress’ at 9.1 oz/fruit. S-50260 produced the highest percentage of cull fruit, though similar to that of HA 3074, Fla 8477, and BHN 745. Based on marketable yield, cull categories, and size and shape of marketable fruit, TYLCV-resistant entries from this trial that could be recommended for observation in small blocks are HA 3074, HA 3075, BHN 745, VT-60774, and ‘Tygress’.
Yellow Nutsedge Management in Plasticulture
Wheeler G. Foshee, III*1, Collin W. Adcock1, Glenn R. Wehtje2, Charles H. Gilliam1, Edgar Vinson1, Jim Pitts3, and Jason Burkett3, 1Auburn University, Department of Horticulture, Auburn, AL 36849; 2Auburn University, Department of Agronomy and Soils, Auburn, AL 36849; 3Alabama Agricultural Experiment Station, Auburn University, Auburn, AL 36849
Field studies were conducted in 2006 at the Auburn University's E.V. Smith Research Center and Chilton County Research and Extension Center in Alabama to determine effects of S-metolachlor and halosulfuron for nutdege control on tomato yields. This was a randomized complete-block design study with a total of six treatments of S-metolachlor (1.25 a.i./acre) applied preemergence (PRE), S-metolachlor (1.25 a.i./acre) and halosulfuron (0.036 a.i./acre) PRE, along with a split application of S-metolachlor (1.25 a.i./acre) PRE followed by halosulfuron (0.036 a.i./acre) postemergence (POST), S-metolachlor (1.25 a.i./acre) and halosulfuron (0.018 a.i./acre) PRE followed by halosulfuron (0.018 a.i./acre) POST, a plastic mulch only treatment, and then a bareground nontreated control. After a period of 40 days after planting, the POST treatments of halosulfuron (0.036 a.i./acre and 0.018 a.i./acre) were applied when nutsedge emergence had reached peak populations. Tomato yields were collected and graded throughout the growing season. At the conclusion of the study approximately 112 days after application (DAA), weed biomass was collected in 8-ft sections of every plot. Due to a combination of weed control and plastic mulch, tomato yields were increased 3-fold compared to bareground treatments. The plastic mulch was readily punctured by yellow nutsedge with or without PRE application of selected herbicides. In addition, no yield response was observed for the plastic mulch, treated or nontreated with herbicides. The nontreated bareground yielded the lowest of all treatments; whereas all other treatments had equivalent yield. Overall efficacy with respect to preventing puncturing of plastic mulch was marginal. In response to these results, plastic mulch is largely limited to a single cropping season. Alternatives may include thicker plastic, multiple layers, or other suitable methyl bromide alternatives.
Performance of Selected Diploid Pollenizers
Joshua H. Freeman*1, Gilbert A. Miller2, and Stephen M. Olson3, 12229 Fifield Hall, Department of Horticulture, University of Florida, Gainesville, FL 32611; 264 Research Road, EREC, Clemson University, Blackville, SC 29817; 3155 Research Road, NFREC, University of Florida, Quincy, FL 32351
As triploid watermelons [Citrullus lanatus (Thunb.) Matsum. & Nakai] increase in popularity, production has shifted away from seeded watermelons. To achieve successful fruit set in triploid watermelons, a diploid watermelon cultivar must be planted as a pollen source. Three diploid cultivars in 2005 and seven diploid cultivars in 2006 were evaluated at one and three locations, respectively, to determine their effectiveness as pollenizers. Each cultivar was planted within plots of the triploid watermelons ‘TRI-X 313’ (2005) and ‘Supercrisp’ (2006) with buffers on all sides of the plots to contain pollen flow within individual plots. Performance of pollenizers was based on triploid watermelon yield, soluble solids, and incidence of hollow heart. In 2005, there were no significant differences in total weight, fruits per hectare, average weight, or total soluble solids between pollenizers. In 2006, significant differences in yield were observed, and plots with ‘Sidekick’ as a pollenizer yielded the highest but were not significantly different than ‘Patron’, ‘SP-1’, ‘Jenny’, or ‘Mickylee’. In 2006, there were no significant differences in fruits per hectare, total soluble solids, or incidence of hollow heart between pollenizers. The experimental design was successful in isolating pollenizers, and there was minimal pollen flow outside of experimental plots, as indicated by minimal fruit set in control plots.
Effects of In-row Distances on Eggplant Yield and Economic Feasibility
Bielinski M. Santos, Gulf Coast Research and Education Center, IFAS, University of Florida
Two field trials were conducted in West Central Florida to determine the effects of varying in-row distances on eggplant (Solanum melongena) yield and economic feasibility. ‘Classic’ eggplant transplants were established at distances between plants of 1, 1.5, 2, 2.5, 3, and 3.5 ft in single rows on polyethylene-mulched beds. Eggplant plant height was determined at 6 weeks after transplanting (WAT), and marketable fruit number and weight were collected through five harvests beginning at 6 WAT. Marginal return rates (MRR) of the two best options were calculated at the end of the study. Results indicated that plant height decreased linearly (y = 30.63 − 2.2x; r2 = 0.71) as in-row distances increased. However, quadratic equations characterized the responses of fruit number (y = 26.29 + 26.00x − 7.73x2; r2 = 0.85) and weight (y = 13.89 + 7.64x − 2.55x2; r2 = 0.86), with 47% and 45% decrease on the predicted values for each variable as in-row distances changed from 2.5 to 3.5 ft. When comparing the economic returns of distances of 2 and 2.5 ft, the latter had 8% higher net returns than the former practice (MRR = 1.08%).
Effects of Pruning on ‘Florida-47’ and ‘Sungard’ Tomato Yields
Bielinski M. Santos, Gulf Coast Research and Education Center, IFAS, University of Florida
Four trials were conducted to assess the effect on tomato yield of pruning side branches at 2 weeks after transplanting (WAT). ‘Florida-47’ and ‘Sungard’ tomato were pruned, allowing one, two, and three main stems to grow. A non-pruned control was also included. Plant height was measured at 3 and 4 WAT in ‘Sungard’ treatments and at 4 and 6 WAT. Marketable fruit weights were collected twice for each cultivar during each season and graded as extra-large, large, and medium fruits. There was significant effect of the pruning regime on the initial measurement of plant height of both tomato cultivars, but that effect disappeared on the latest observation. For tomato fruit yield, there was no effect of pruning on fruit weight per category and on total fruit weight. This indicated that growers may not require this field practice, reducing labor costs and possible transmission of diseases through mechanical removal of the side branches.
Organic Vidalia Onion Production
G.E. Boyhan*1, Ray Hicks2, Reid Torrance3, Chris Hopkins4, Cliff Riner3, and Randy Hill5, 1East Georgia Extension Center, Nessmith-Lane Bldg. 2nd Floor, Statesboro, GA 30460; 2Screven Co. Extension, 321 Rocky Ford Rd, Sylvania, GA 30457; 3Tattnall Co. Extension, PO Box 558, Reidsville, GA 30453; 4Toombs Co. Extension, 200 Courthouse Square, Suite 1, Lyons, GA 30436; 5Vidalia Onion and Vegetable Research Center, 8163 Hwy 178, Lyons, GA 30436
Organic Vidalia onion production is a relatively new endeavor for our growers. Vidalia onions are short-day plants grown as an overwintering crop in southeast Georgia. They are well known throughout North America for their mild sweet flavor and consequently command a premium price in the marketplace. Their popularity has resulted in onion buyers requesting organic Vidalia onions. These onions are seeded in September in high-density plantings that are then transplanted to their final spacing in mid-winter (November and December), and harvested in April and May. Research at the University of Georgia began in 2001 on organic onion production. One of the first experiments was with poultry litter as a fertilizer source for transplant production, which indicated that 6 tons/acre was adequate to meet the fertilizer requirements for transplants, particularly nitrogen requirements. In another experiment, compost at 5 or 10 tons/acre was found to be inadequate as a fertilizer source, but did have a synergistic effect with organic fertilizer (4−2−3 at 130 lbs/acre N). Poultry litter at 6 tons/acre also was also adequate to produce dry bulb onions (from transplanting to harvest). The synergistic effect of compost in combination with organic fertilizer (4−2−3 at 150 lbs/acre N) was also observed with dry bulb production. Fertilization either from poultry litter or commercial organic fertilizers is not a problem. The biggest challenge facing growers is weed control. Plastic mulch, compost mulch, cultivation, and hand-weeding are all used with varying levels of success.
Vegetable Crops Section—Cowpea
Evaluation of Legume Cooking Characteristics using a Rapid Screening Method
H. Yeung1, R.W. Waniska1, and J. Ehlers2, 1Cereal Quality Laboratory, 370 Olsen Blvd., Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474; 24113 Batchelor Hall, Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521-0124
While most legumes are consumed as cooked whole seeds, consumer preferences for legume cooking properties should also be considered and at an earlier stage in the breeding process. Hence, we developed an effective and low-cost method to analyze the cooking quality attributes of new varieties, in order to advance breeding lines. The objective is to use a rapid screening method to evaluate the cooking quality attributes of several cowpea (Vigna unguiculata) varieties and relate physicochemical characteristics with sensory attributes. Samples (5 g) were taken from 58 cowpea varieties and boiled in plastic bags until the majority of the seeds were cooked. The samples were evaluated in batches of 25 and replicated four times. Broth was drained and the seeds and their broth were separated into dishes with covers. Samples were rated for aroma intensity, the number of split testa and cotyledons, turbidity of the broth, cooked doneness, and hardness. Textural properties of cooked samples were determined by Kramer-shear test using the TA.XT2 Texture Analyzer. Many cooking properties were significantly affected by cowpea cultivars, while the environment (two locations) also affected cooking properties. Cooking properties of undercooked samples were also changed when provided an additional 5 minutes of cooking time. The texture analysis confirmed the subjective ratings of cooked doneness and tactile texture. Thus, the rapid cooking quality evaluations were repeatable and permitted differentiation of legume cooking properties between cultivars and environment. Legumes can then be ranked into preferred and less preferred categories due to specific cooking requirements of the food processor or consumer.
Tolerance of Cowpea to Halosulfuron and Sulfentrazone
N.R. Burgos1, L. Brandenberger2, L. Wells2, D. Motes1, T.E. Morelock3, S. Eaton1, L. Martin1, J. Bullington1, C. Baquireza1, and V. Shivrain1, 1Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701; 2Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74708; 3Deaprtment of Horticulture, University of Arkansas, Fayetteville, AR 72701
The standard herbicide program for cowpea in the southern United States is not effective on emerging weed problems—Acalypha ostryifolia, Solanum spp., and acetolactate synthase (ALS)-resistant Amaranthus palmeri. Halosulfuron and sulfentrazone were evaluated as potential alternative herbicides. Experiments were conducted at Kibler, Ark., and Bixby, Okla., in 2006 using sulfentrazone, applied preemergence (PRE), or halosulfuron applied PRE or postemergence (POST). For the sulfentrazone experiment, six cultivars and four advanced lines were tested using a.i. at 0.42 (commercial rate) and 0.84 kg·ha−1 at Kibler. At Bixby, 0.21 and 0.42 kg·ha−1 a.i. were used. At Kibler, cultivar and herbicide rate had no interaction effect on crop stand, but the main effects were significant. Averaged over cultivars, cowpea stand was reduced 12% by the commercial rate and 32% by the 2× rate relative to the control. Averaged over herbicide rates, 00-855, ‘AR Blackeye’, and ‘CT Pinkeye’ incurred the least stand loss (12% to 15%). The degree of stunting differed between cultivars and between herbicide rates 2 weeks after planting (WAP). Averaged over herbicide rates, 00-855, ‘AR Blackeye #1’, ‘CT Pinkeye’, and ‘Early Scarlet’ showed the least growth reduction of 18% to 23%. Averaged over cultivars, the commercial rate caused 10% stunting and the 2× rate, 52%. At Bixby, the commercial rate caused 2% to 22% injury at 4 WAP, similar to what was observed at Kibler. The a.i. at 0.21 kg·ha−1 rate generally caused <10% injury and did not cause any yield reduction. The yields of ‘Early Acre’, ‘CT Pinkeye’, 92-551, 01-1764, and 01-243 were not affected by the commercial rate. Therefore, several cultivars are tolerant to 0.42 kg·ha−1 a.i. sulfentrazone. The margin of tolerance is increased by reducing the herbicide rate. For the halosulfuron experiment, 20 advanced lines and the commercial standard, ‘Early Scarlet’, were evaluated at Kibler. The commercial rate (0.05 kg·ha−1) and twice that were used. Halosulfuron is safe to use on cowpea when applied PRE at the commercial rate. When a 2× rate is used, about 50% of cowpea entries incurred yield loss. Postemergence application of halosulfuron, at the commercial rate, caused significant stunting and yield loss to the majority of cowpea lines tested.
Hand-harvested Southernpeas in Central Mississippi—2006 Results
W.B. Evans*, P.M. Hudson, and K.L. Paridon, Mississippi State University, Truck Crops Branch, Crystal Springs, MS 39059-0231
In Summer 2006, twenty-four southernpea [Vigna unguiculata L. Walp. subsp. unguiculata (L.)] cultivars and advanced lines were evaluated for yield and quality at Crystal Springs, MS in a non-irrigated trial. Pods were hand-harvested at the green-shell stage on six dates in Sept. 2006. In-shell fresh weights, shelled seed weight, and percent shell-out were recorded. Pest and disease pressure were light. A wind event 2 days prior to first harvest caused significant lodging of the plants. Fresh seed yield ranged from under 2000 to just over 4000 lbs/acre. Top yielding entries included ‘Arkansas Blackeye No. 1’, ‘Top Pick Brown Crowder’, ‘Mississippi Pinkeye’, ‘Excel S’, and two lines from the University of Arkansas. Fresh seed yield for most entries within a seed class were not significantly different from one another. Percent shell-out ranged from 31% to 52% on a fresh weight basis. The weighted average days to 50% harvest ranged from 54 to 62 days. Of those entries tested in at least two of the four most recent years, the fresh seed yield of the following entries always exceeded that year's mean yield for all entries: ‘Top Pick Brown Crowder’, ‘Mississippi Pinkeye’, ‘CT Pinkeye’, ‘Quick Pick Pinkeye’, ‘Top Pick Pinkeye’, and ‘Epic’. This trial does not address performance for machine harvest.
Fortuitous Existence of Resistance to Callosobruchus maculatus in Cowpea Cultivars Commonly Grown in Alabama
L.E.N. Jackai, G.A. Awuni, and B.N. Dingha, Department of Agricultural and Environmental Sciences and GWC Agricultural Experiment Station, Tuskegee University, Tuskegee, AL
Yield loss in cowpea resulting from the feeding damage of the cowpea curculio (Chalcodermus aeneus Boheman), the southern green stink bug (Nezara viridula Linn.), and the cowpea bruchid (Callosobruchus maculatus Fab.), which is often erroneously referred to as the cowpea weevil, is an important concern in the production of cowpeas in Alabama. The bruchid and curculio infest mature pods in the field and are transported to storage where damage increases as the larvae grow bigger. Damaged cowpeas usually cannot be marketed. The bruchid is multivoltine (i.e., produces several generations) and therefore continues to multiply in storage. A study was conducted to evaluate the ability of certain cultivars to withstand infestations that cause severe damage on other cultivars. The study was prompted by the findings that after storage for 3-4 weeks some commonly grown cultivars suffered comparatively little damage from the bruchid and curculio, two pests that were recovered in stored peas. Cowpeas of five cultivars [‘Mississippi Purple’ (MP), ‘Mississippi Silver’, ‘Pinkeye Purple Hull’, ‘Mississippi Pinkeye Purple Hull’, and ‘California Blackeye’ (CB5)] were infested with several pairs of bruchids for 24 hours for egg laying; all eggs were then scraped off leaving only one per seed. Five replications of 50 seeds for each cultivar were then held for 55 days in the laboratory. Data were collected on adult emergence (S), duration of larval period (TDT); a growth index (GI) (log S/TDT), was calculated and used to separate the cultivars. CB5, which was also used to maintain the bruchid culture, had the highest and earliest adult emergence and the shortest TDT while ‘Mississippi Purple’ had the lowest and longest TDT. On the basis of the GI, it was clear that CB5 provided the most suitable substrate (high GI value, 50.3 × 10−3) for larval survival, and MP the least (low GI, 35.0 × 10−3). Other cultivars were rated as intermediate. We are uncertain what factors are responsible for these results, but investigations are in progress to characterize the proteins profiles and allelochemicals in these cultivars. These cultivars were not deliberately bred for resistance to the cowpea bruchid; any such resistance would therefore be considered fortuitous. Intended or not, such resistance would be of immense value in reducing the need for fumigation of stored peas.
Vegetable Crops Section—Sweetpotato
Starch Biosynthesis and Genetic Modifications of Starch in Sweetpotato (Ipomoea batatas L.) Storage Roots
William A. Akwe1, Glory, M. Ashu1, Lakeisha Stewart1, Celestine Fosung1, Adeline Douanla1, Qun Xia1, Janice Bohac2, Deepak Bhatnager3, Victor Njiti1, Samuel Besong1, Sandra Barnes1, Shoucheng Zhang1, and Ming Gao*1, 1Center for Biotechnology and Genomics, Alcorn State University, MS 39096; 2US Vegetable Lab, Charleston, SC; 3USDA-ARS, New Orleans, LA
To develop specialty sweetpotato cultivars for valued-added food and industrial uses, studies on biosynthesis and genetic modifications of starch in the sweetpotato have been conducted. To develop cultivars producing amylose-free starch using the postranscriptional gene silencing (PTGS) approach, we have isolated a total of 11 homeologous and paralogous genomic intervals of granule-bound starch synthase I (GBSSI) genes from sweetpotato. These sequence data indicate that the GBSS I gene most likely has three copies per haploid genome of each of the three diploid genomes in sweetpotato. PTGS constructs for silencing the GBSSI in sweetpotatoes are being prepared. Sequences in some introns of these GBSSI genomic intervals showed an ordered similarity/divergence patterns, implying homeologous recombination events during their evolution course. We hypothesized that these unique sequence similarity patterns, and sequences specific to a sub-group of GBSSI intervals may be specific to a particular diploid genome in sweetpotato, and can be used as genome-type markers for phylogenetic studies on origins of the three diploid genomes in the Sweetpotato genome. To test the hypothesis, we isolated a total of 41 GBSSI genomic intervals from 10 diploid and one tetraploid sweetpotato relatives. Sequences of these genomic intervals revealed that sweetpotato should have an allo-hexaploid, consisting of three diploid genomes of different origins. Diploid species with genomes closest to those in the hexaploid sweetpotato genome were also identified. We also investigated sizes of starch granules from several cultivars or breeding lines in USA. Starch granules from Excel and SC1149, which happened to be the parents of a Psuedo-F2 mapping population, displayed the largest size difference. To understand the genetic mechanism controlling the granule sizes, phenotyping the population for the granule size and development of SSR markers are underway. To better understand starch biosynthesis in sweetpotatoes, granule-bound proteins, were extracted, resolved using a modified SDS-PAGE method, and peptide sequenced. Most of these granule bound proteins are isoforms of starch synthases or starch branching enzymes. These studies have laid the ground for genetic engineering of starch in sweetpotatoes.
Detection of Sweetpotato Viruses by NCM-ELISA
D.L. Gutierrez and R.A. Valverde, Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803
Viral diseases can lower sweetpotato yields. Currently, the most widely used control strategy for sweetpotato viruses is the implementation of programs that provide virus-tested materials to growers. However, these materials can be rapidly reinfected in the field. Sensitive, reliable, and inexpensive methods are thus needed to detect viruses in plants that have become reinfected so that they can be eliminated from seed programs. Diagnosis of sweetpotato viruses has become complex due to the incidence of mixed infections and increased reports of new viral species and strains. Sweetpotato virus detection methods include inoculation of indicator hosts, enzyme-linked immunosorbent assay (ELISA), molecular hybridization and polymerase chain reaction (PCR), but some of them may not be practical in some laboratories. A membrane immunobinding assay known as NCM-ELISA has been used with success to detect several sweetpotato viruses. This method has been adapted for practical virus detection by the International Potato Center, and detection kits for several sweetpotato viruses have been developed. This format is particularly valuable in developing countries as it requires few resources to perform effectively. Using this method the following potyviruses were successfully detected with polyclonal antisera: Sweet potato feathery mottle virus (several strains), Sweet potato virus G, and Ipomoea vein mosaic virus. Similarly, Sweet potato chlorotic stunt virus was detected using monoclonal antibodies.
Associations of In-season Chrysomelid Beetle Density and Sweet Potato Damage in Mississippi Sweet Potatoes
J.T. Reed, M.R. Williams, D. Fleming, and C. Jackson, Department of Entomology and Plant Pathology, Mississippi State University. P.O. Box 9775, Mississippi State, MS 29762
Results of weekly sampling of insects in sweet potato foliage and evaluation of insect damage on harvested roots from multiple commercial sweet potato fields over the years 2004, 2005, and 2006 are discussed. Seventeen insect species in the family Chrysomelidae, representing 10 genera, were collected. Chaetocnema confinis (sweet potato flea beetle), Systena frontalis (flea beetle), and Diabrotica undecimpuctata howardi (12-spotted cucumber beetle) were the most common root-damaging species. Diabrotica balteata, the banded cucumber beetle, was present in very low numbers. Tortoise beetles and other leaf beetles collected from the foliage included four species of cassidine tortoise beetles, nine species of alticine flea beetles, the southern corn leaf beetle (Myochrous denticollis), and the bean leaf beetle (Ceratoma trifurcata). These leaf-feeding pests were not sufficiently numerous in any field to cause serious problems. Seasonal average insect numbers were positively correlated with the mean number of insect-specific scars per potato for C. confinis and the Systena spp. aggregate in 2004, 2005, and 2006, but Diabrotica undecimpuctata howardi numbers correlated with Diabrotica damage only in 2004 and 2006. The mean numbers of Systena flea beetles in sweep-net samples also correlated positively with number of insect scars identified as cucumber beetle scars and sweet potato flea beetle scars in 2004 and 2005, sweet potato flea beetle scars, and a consolidated scar rating from all insects (SDW = Systena, Diabrotica and Wireworm damage combined). Rainfall in 2004 and 2005 was adequate for sweet potato production, but serious drought conditions existed most of the season in 2006. From 10% to 30% of potatoes, depending on the year, had damage from Systena flea beetles and 12-spotted cucumber beetles combined.
Nitrogen Application and Rate Considerations to Optimize Yields of ‘Covington’ Sweetpotato
Jonathan R. Schultheis*, Allan C. Thornton, Mark A. Seitz, and William B. Thompson, Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609
‘Covington’, a sweetpotato variety released in 2004 by North Carolina State University, was evaluated for its response to nitrogen (N) fertilizer rate and method of application in three locations which were representative of commercial sweetpotato fields. In one location, little response to N was obtained, as the no N application control treatment yielded as many U.S. no. 1, canner, and jumbo roots as all other N rate treatments in which rates up to 135 kg·ha−1 were applied. Residual N from the previous cropping season and the retention of N in the “heavier” sandy loam soil likely contributed to no response to N treatment in location 1. Although nonsignificant, in location 2, the 67 and 101 kg·ha−1 split application and the 101 and 135 kg·ha−1 one-time application generally resulted in 10% to 15% more U.S. no. 1 roots than the lower N rates and the no N treatment. Total yields generally increased as ammonium nitrate (AN) rates increased from 0 to 135 kg·ha−1 N. The planting in location 3 was comprised of a deep sand and responses to both N rate and application were significant. As the N rate increased from 0 to 135 kg·ha−1, regardless of application method or rate, total and U.S. no. 1 yields increased. Application of AN 2 times resulted in superior yields and more jumbo-sized roots than if applied one time. Across the three experiments, the response to N was variable and was likely dependent of residual N and soil types. The application of at least 67 kg·ha−1 N appears to be beneficial in most cases for high yields of ‘Covington’ sweetpotato. Additional yield improvement may also be obtained with 101 to 135 kg·ha−1 N in soils with less ability to retain N or in soils with less N residual from the previous crop. The use of two applications was often superior to one application of N.
Anthocyanin Content and Antioxidant Activity of Purple-fleshed Sweetpotato Collections
C.C. Teow1, V.D. Truong*1,2, R.L. Thompson2, R.F. McFeeters1,2, K. Pecota3, and G.C. Yencho3, 1Department of Food Science; 2USDA-ARS, SAA Food Science Research Unit; 3Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695
Purple-fleshed sweetpotatoes can be a healthy food choice for consumers and a potential source for natural food colorants. Characterization of the pigments and other polyphenolic compounds responsible for antioxidant activity is important for breeding programs and the development of value added processed products from purple-fleshed sweetpotatoes. The objective was to analyze the polyphenolic compounds and antioxidant activity in fresh and steamed samples from a diverse group of purple-fleshed sweeetpotatoes from several countries in Asia and South America. Freeze-dried powders of raw and steamed roots of 21 genotypes with different shades of purple color were extracted with acidified methanol using a Dionex ASE 200 accelerated solvent extractor. The extracts were analyzed for total monomeric anthocyanin (TMA) content by a pH-differential method, total phenolic (TP) content by the Folin-Ciocalteu procedure, and antioxidant activity by the oxygen radical absorbance capacity (ORAC) assay. Individual anthocyanin pigments were analyzed by UV-visible-HPLC. The TMA, TP and ORAC values of the raw storage roots were 12-160 mg cyanidin-3 glucoside equivalents/100g fresh weight (fw), 30.8-136.0 mg chlorogenic acid equivalents/100g fw, and 3.1-31.1 μmol trolox equivalents/g fw, respectively. Steamed cooking resulted in significant increases (P < 0.05) in TP contents of all samples. A similar effect of steaming was also observed for the TMA and ORAC values in most of the evaluated genotypes. In a few cases TMA and ORAC values were lower after steaming. Eight major anthocyanin components were detected with HPLC. Peonidin: cyanidin ratios varied widely among the raw and steamed samples, indicating the diversity in anthocyanin pigments among the collected genotypes.
Assessment of Procedures to Quantify Insect Damage on Sweetpotato Roots
D. Michael Jackson, USDA, ARS, US Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414
There are many soil insect pests that damage sweetpotato roots in the southeastern United States. After the roots are harvested, it is difficult to distinguish between injury symptoms caused by different pest species. Also, pest populations and subsequent damage levels fluctuate significantly from year to year, from location to location, from field to field, and sometimes within fields. To further complicate the quantification of pest impact, we have found a positive relationship between damage ratings and root weight, and sweetpotato genotypes vary widely in yields within grades. Therefore, it is difficult to interpret comparisons of insect ratings between high yielding and low yielding genotypes. Thus, a sweetpotato genotype that produces many small roots might appear more resistant than a genotype that produces many large roots, even if the actual resistance levels were the same in these genotypes. Therefore, we developed a new algorithm that better estimates pest damage ratings for sweetpotato genotypes that vary widely in yields and pest resistance. Currently, we rate every root within a plot for insect damage. This is done after roots are weighed and separated into four quality grades: small canners, large canners, U.S. no. 1s, and jumbos. This procedure is slow, labor intensive, and limits the number of genotypes we can evaluate each season for pest resistance. Therefore, we used computer simulations to evaluate different sub-sampling procedures for quantifying pest damage on known populations of several sweetpotato genotypes that were established by individually rating every root in 25-plant field plots replicated 4 times. Sub-sampling schemes for predetermined numbers of total roots included: 1) random selection, 2) fixed sample sizes within grades, and 3) proportional sample sizes within grades. It is hoped that through these efforts, a more-efficient sampling and evaluation procedure can be developed that will allow more “through-put” in the USDA-ARS host plant resistance breeding program for sweetpotato.
Survey of Postharvest Handling Practices on North Carolina and Louisiana Sweetpotato Packinglines
B.A. Edmunds*1, C. A. Clark2, G.J. Holmes1, and E.D. Gray2, 1Department of Plant Pathology, NCSU, Raleigh, NC 27695; 2Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA 70803
In 2005 and 2006, forty-six sweetpotato packinglines in Louisiana and North Carolina were surveyed to characterize their design and measure impacts that occur during normal packing operations. Impact forces were measured using an accelerometer sensor commercially available as the SmartSpud™ (Sensor Wireless, PEI, Canada). The sensor, encased in a custom designed sweetpotato-shaped silicon casing, was run over packinglines alongside roots during packing operations (5 times per packingline). Impacts occurring at the transitions between pieces of equipment were characterized by the drop height and impact surface (PVC rollers, conveyor belts, etc). In both states, high impacts occurred on sizers with drop-roller sizers averaging 19.2 G and electronic sizers averaging 21.6 G. Dumping, especially onto hard metal surfaces or onto other roots in the tank also resulted in high impacts (9.3–16.7 G). Although each packingline is unique, some generalizations can be made. Packinglines in Louisiana compared to North Carolina were shorter (80 ft vs. 123 ft) with fewer turns (2 vs. 3) and lower cumulative impacts (87 G vs. 148 G). A detailed summary report of the packingline surveys and an individualized report was prepared in Aug. 2006 and sent to all packers in both states. The information from these surveys will be used to develop a model to characterize the effect of repeated packingline impacts on quality issues such as weight loss and the development of Rhizopus soft rot.
Sweetpotato Weevil in Louisiana: Distribution and Management
T. Smith1 and A. Hammond2, 1LSU AgCenter Sweet Potato Research Station, Chase, LA 71324; 2LSU AgCenter Department of Entomology, Baton Rouge, LA 70803
The sweetpotato weevil [Cylas formicarius (F.)] is the most damaging insect pest of sweet potato [Ipomoea batatas (L.)] in both tropical and subtropical areas worldwide. Cylas formicarius can attack sweet potatoes in the field and in storage. Larvae feeding on sweet potato roots can produce major economic damage and yield loss. An effective integrated pest management program is multidisciplinary and includes numerous management options. Several tactics are employed to manage the sweetpotato weevil in Louisiana including cultural techniques, monitoring with pheromone traps, and routine application of insecticides. Insecticides have traditionally been the primary defense in reduction of root damage by insects to sweet potato and despite the fact that insecticides are a valuable tool used in pest management systems, many drawbacks can exist such as the development of insect resistance. Currently, C. formicarius is established only in southern regions of Louisiana, and a quarantine program exists to minimize the spread of C. formicarius into northern production areas of the state. In addition, a mandatory spray program is enforced in areas where the sweetpotato weevil is established to help manage sweetpotato weevil populations in southern Louisiana. Two cohorts of sweetpotato weevil were subjected to a series of insecticide bioassays in 2004 and 2005. This presentation discusses results obtained in these bioassays and examines the current integrated pest management approach for this insect in Louisiana.
Content and Potential Biological Activity of Dicaffeoylquinic Acids in Sweetpotato Storage Roots
H. F. Harrison1, Jr., T.R. Mitchell, J.K. Peterson1, M.E. Snook2, and W.P. Wechter1, 1U.S. Vegetable Laboratory, USDA-ARS, 2875 Savannah Highway, Charleston, SC 29414; 2Russell Research Center, University of Georgia, Athens, GA 30604
Three dicaffeoylquinic acid isomers (3,4-, 3,5-, and 4,5-DCQA) were identified in sweetpotato (USPI 399163) storage root cortex by methanol extraction followed by preparative-reversed phase and silicic acid column chromatography. Structures were confirmed by HPLC-MS. DCQAs were quantified in the storage root periderm, cortex and stele of 17 sweetpotato genotypes. The 3,5-DCQA isomer comprised >70% of the total DCQAs in most instances. Levels of 3,5-DCQA averaged 490, 2570, and 670 μg·g−1 in periderm, cortex and stele, respectively. Contents of 3,5 DCQA in individual clones ranged from 0-1700 μg·g−1, 800-7400 μg·g−1, and 200-1600 μg·g−1 in periderm, cortex, and stele, respectively. Ipomoea pandurata cortex and stele were very high in DCQA's and contained almost equal amounts of all three isomers. Ipomoea pandurata cortex contained 22,000 μg·g−1 (2.2% dry weight) and stele contained 24,000 μg·g−1 (2.4% dry weight) DCQA's. Ipomoea pandurata periderm contained only 0.04% dry weight DCQA. All three isomers of DCQA were isolated from PI 399163 cortex, and tested for biological activity. The 3,5 DCQA isomer was inhibitory in Fusarium solani and proso millet bioassays which suggests it may contribute to the allelopathic potential and disease resistance in sweetpotato. The 3,4- and 4,5-DCQA isomers were not as inhibitory as 4,5-DCQA in the bioassays.
QTL Analyses of Dry-matter, Starch and Beta-carotene Content in Sweetpotato
J.C. Cervantes-Flores1, B. Sosinski1, K. Pecota1, R.O.M. Mwanga2, G.L. Catignani3, and G.C. Yencho*1, 1Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695; 2Namulonge Agricultural and Animal Production Research Institute (NAARI), P.O. Box 7084, Kampala, Uganda; 3Department of Food Science, North Carolina State University, Raleigh, NC 27695
Genetic analyses were performed using a sweetpotato [Ipomoea batatas (L.) Lam] mapping population derived from a cross between ‘Tanzania’, an African landrace, and ‘Beauregard’, the most popular sweetpotato cultivar in the U.S. Analyses were done on AFLP maps of both parental clones. The characteristics of the maps were as follows: the ‘Tanzania’ map consisted of 946 single dose markers ordered into 86 linkage groups, and the ‘Beauregard’ map consisted of 704 markers ordered into 90 linkage groups. The traits studied were dry-matter and starch content, yield, and beta-carotene content. Several QTLs were identified that affect these traits in both parental maps, and their importance in the inheritance of these traits is discussed in this paper. Strong correlations were observed between carotene content and starch content in the storage roots, and also between starch content and dry-matter content.
Growing ‘Okinawan’ Sweetpotatoes in Louisiana: Preliminary Yield Trials and Initial Impressions
A.Q. Villordon1, J.W. Franklin1, T.P. Talbot1, W. McLemore1, C. Clark2, M. Hoi2, and D. LaBonte3, 1LSU AgCenter Sweet Potato Research Station, Chase, LA 71324; 2LSU AgCenter Department of Plant Pathology and Crop Physiology, Baton Rouge, LA 70803; 3LSU AgCenter Department of Horticulture, Baton Rouge, LA 70803
We evaluated the suitability of growing ‘Okinawan’ purple-fleshed sweetpotatoes under Louisiana conditions and cultural practices recommended for the ‘Beauregard’ variety. ‘Okinawan’ sweetpotato plants were purchased from a specialty plant distributor and were sent to the LSU AgCenter Department of Plant Pathology and Crop Physiology for virus testing. After being found to be apparently free of viruses, three mericlones were sent to the Sweet Potato Research Station to generate planting materials. After an initial greenhouse-based increase, cuttings were transplanted to the field. These field-grown plants were used as source of transplants for the study. The experimental field (Gigger silt loam; fine-silty, mixed, thermic, Typic Fragiudalf) located at Chase, LA, was disk cultivated and Lorsban 4E (chlorpyrifos; 2 qt/acre) was broadcast applied. A second disking operation was performed prior to hipping in 42-inch rows. Plots were 42 inches wide and 25 feet long. Liquid fertilizer was applied at a rate of 40 lb/acre N, 110 lb/acre P2O5, and 110 lb/acre of K2O. A four-row strip was not fertilized to investigate the response of ‘Okinawan’ sweetpotatoes to low fertility conditions. A tank mix of Command 3ME (clomazone; 2 2/3 pt/acre) and Valor (flumioxazin; 2 oz/acre) was applied immediately prior to mechanical transplanting (in-row spacing=12 inches) on 2 June 2006. At 128 days after transplanting, a one-row mechanical digger was used for harvesting. Roots belonging to various yield grades were combined and weighed. The yield of the Okinawan sweetpotatoes was about 2.5 times less than the yield of ‘Beauregard’. There were no differences in yield among the mericlones as well as fertilizer treatments. We noted the incidence of cracking among ‘Okinawan’ storage roots from fertilized plots as well as extensive damage from whitefringed beetle. In addition, the ‘Okinawan’ storage roots were set deeper compared to ‘Beauregard’, requiring additional manual work to dig out the storage roots. The results suggest that the ‘Okinawan’ sweetpotato variety can be grown under Louisiana conditions but may require a longer growing season than ‘Beauregard’. In addition, further research is needed to verify the role of in-row spacing and fertilizer rates in improving potential yield.
Vegetable Crops Section—Watermelon
Carotenoid Analysis using the Puree Absorbance Method for Germplasm Screening
Angela R. Davis1, Wayne W. Fish1, Penelope Perkins-Veazie1, Amnon Levi2, and Stephen R. King3, 1South Central Agricultural Research Lab, USDA-ARS, P.O. Box 159, OK 74555; 2U.S. Vegetable Laboratory, USDA-ARS, Charleston, SC; 3VFIC, Texas A&M University, College Station, TX
Many fruits and vegetables contain health-promoting compounds that require labor intensive analyses to detect. This is the case with quantifying carotenoids in fresh fruits and vegetables. Carotenoid content can vary significantly between varieties; therefore a method to rapidly screen germplasm for high carotenoid levels is desirable. Many labs have attempted to develop reflectance colorimetric methods to determine carotenoid content with varying degrees of success. Attempts to use reflective colorimetric values to estimate lycopene content in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] has not been successful. To avoid the inherent problems with reflective color readings on the surface of cut watermelon, our group has successfully utilized a xenon flash spectrophotometer to measure absorbance of opaque purees of watermelon flesh. This absorbance can then be used to estimate total lycopene content in red fruit and total carotenoid content in canary yellow-fleshed watermelons. We have shown that our puree absorbance method also works well for estimating lycopene in fresh tomato purees and many processed tomato products. Preliminary results suggest that this method will also work for beta-carotene in cantaloupe and prolycopene in orange watermelon. The R2 values using this method compare well with other published methods with ranges between 0.88 and 0.99 depending on the type of fruit and carotenoid being evaluated. The puree absorbance method is fast, accurate, requires no hazardous solvents, and yields values comparable with other analytical methods.
Broad Mite (Polyphagotarsonemus latus) Infestation and Injury in Watermelon and Potential Sources of Resistance
C.S. Kousik1, A Levi1, A.M. Simmons1 R. Hassell2, and B.M. Shepard2, 1U.S. Vegetable Laboratory, USDA-ARS, Charleston, SC; 2Clemson University, CREC, Charleston, SC
During the summer of 2006, we observed severe broad mite (Polyphagotarsonemus latus) injury and infestations on watermelon plant introductions (PI) and commercial cultivars grown in the field in Charleston, S.C. Broad mites have previously not been reported on watermelons in the United States. However, they have the potential to emerge as a serious pest. Injury was mainly observed on the growing terminals and the tender apical leaves which were bronzed and grew poorly, and in some cases were distorted and curled upwards. We evaluated 219 PI accessions belonging to the watermelon core collection (GRIN, USDA, ARS, Griffin, GA) for broad mite injury and infestation that occurred naturally. Nine PI lines (4%) had no visible broad mite injury in the field compared with a commercial cultivar ‘Mickey Lee’ which was severely injured. Broad mites were extracted by washing the growing terminals with boiling water and counting the mites under a stereomicroscope. ‘Mickey Lee’ had higher broad mite counts compared with some of the PI accessions with no visible injury. Fourteen PI accessions were further evaluated in the greenhouse to confirm their resistance by artificially infesting them with broad mites that had been cultured on susceptible watermelon plants. PI accessions belonging to Citrullus lanatus var. lanatus (PI 357708), C. lanatus var. citroides (PI 500354), C. colocynthis (PI 386015, PI 386016, PI 525082) and Parecitrullus fistulosus (PI 449332) had significantly lower broad mite injury ratings and counts compared with Mickey Lee. These PIs may serve as potential sources of broad mite resistance.
Tolerance of Select Watermelon Plant Introductions (PI) to Watermelon Vine Decline in Florida
C.S. Kousik1, S. Adkins2, and P.D. Roberts3, 1US Vegetable Laboratory, USDA-ARS, Charleston, SC; 2USHRL, USDA-ARS, Ft. Pierce, FL; 3SWFREC, University of Florida, Immokalee, FL
Watermelon vine decline (WVD), also known as mature watermelon vine decline, has been a major limiting factor in watermelon (Citrullus lanatus) production in southwest and west central Florida for the past several years. Symptoms of WVD typically occur at harvest time or 1 to 2 weeks prior to harvest. The disease causes sudden decline of the vines and can also affect the fruit quality. WVD has been estimated to have caused more than $60–$70 million in losses in Florida. Recently it was determined that a novel whitefly (Bemisia tabaci) -transmitted ipomovirus (family: Potyviridae), named squash vein yellowing virus (SqVYV), was the causal agent of this disease. We evaluated 218 plant introductions (PI) belonging to the watermelon core collection for tolerance to SqVYV by mechanical inoculations of the plants in a greenhouse. Several PIs with tolerance to SqVYV were identified in the greenhouse and further screened in the field in Immokalee, Fla. Field screening was conducted in Fall 2006 by planting a SqVYV infected squash plant in each watermelon PI plot and rating for disease development three times during the season. Overall, PI 500354 (C. lanatus var. citroides) and PI 386024 (C. colocynthis) were the most tolerant to SqVYV compared with ‘Mickey Lee’ and ‘Crimson Sweet’, which were highly susceptible. We also observed variability in the resistant reaction to SqVYV within these PIs. SqVYV was detected using DNA probes in the plants and fruits of the susceptible cultivars but not in the tolerant PIs. Further evaluations and selections will be made in the coming seasons to confirm the reactions of these PI to WVD.
Evaluation of Commercial Watermelon Rootstocks for Tolerance to Phytophthora Blight and Watermelon Vine Decline
C.S. Kousik1, S. Adkins2, P.D. Roberts3, and Richard Hassell4, 1USDA, ARS, U.S. Vegetable Laboratory, Charleston, SC; 2USHRL, USDA-ARS, Ft. Pierce, FL 34945; 3University of Florida SWFREC, Immokalee, FL 34142; 4Clemson University, CREC. Charleston, SC
Phytophthora blight and fruit rot, caused by Phytophthora capsici, and watermelon vine decline (WVD) in Florida, caused by squash vein yellowing virus (SqVYV), are two important and emerging diseases of watermelons (Citrullus lanatus). Recently, the practice of grafting seedless watermelons (triploids) onto rootstocks of other Cucurbitaceae genera also has been gaining importance for disease management. We first evaluated 5-week-old plants of commercial rootstocks without the scion for tolerance to phytophthora blight by inoculating them with a zoospore suspension (10,000 zoospores/plant) consisting of a mixture of seven isolates of P. capsici in a greenhouse in Charleston, S.C. Commercial rootstocks ‘Macis’ and ‘Emphasis’ (Lagenaria spp.) were tolerant to phytophthora blight compared to ‘RS-1330’, ‘PST04-109W’, and ‘Shintosa-Camel’. Similarly, triploids grafted on ‘Macis’ or ‘Emphasis’ appeared to be tolerant compared to the susceptible cultivar Black Diamond or on other rootstocks. We mechanically inoculated a different set of the same rootstocks with SqVYV (causal agent of WVD) in a greenhouse in Ft. Pierce, Fla. Rootstocks of ‘Emphasis’ and ‘Macis’ appeared to be tolerant to the virus compared with other rootstocks or the seedless watermelon ‘Petite perfection’, which was very susceptible. Although ‘Emphasis’ and ‘Macis’ rootstocks were tolerant to SqVYV, watermelon plants grafted on them were still very susceptible. Similarly, the grafted watermelon scions on all rootstocks were highly susceptible to WVD in the field in Immokalee, Fla. We will be conducting further studies in the fields in Charleston, S.C., to test the effectiveness of rootstocks and grafts against P. capsici and similarly evaluate grafted watermelons for tolerance to WVD in Florida.
Adding Value to Grafted Watermelon: Novel Benefits and Potential Pitfalls
Bubba LaMolinare1,2, Tom Isakeit2, Angela Davis3, Wenge Liu4 and Stephen King1, 1Vegetable & Fruit Improvement Center, Department of Horticultural Sciences; 2Texas Cooperative Extension, Texas A&M University; 3USDA-ARS, Lane, OK; 4Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
Grafted watermelons are commonly used in Asia and areas of Europe but, currently, are not as widely used in the United States. The traditional reason for grafting watermelons has been for resistance to soilborne diseases such as fusarium. We began to explore novel benefits which might make grafted watermelons more economical for producers in the United States. Cold tolerance and the possible transmission of desirable transgenic traits from the rootstock to the scion were two areas of investigation. We also examined the potential for rootstocks to transmit watermelon fruit blotch to the scion. Increased cold tolerance was observed when a selected rootstock breeding line was grafted to ‘Ole’. Plants were placed in a cold chamber at 5 °C for 7 days. Both the ungrafted rootstock and grafted ‘Ole’ showed less physical signs of injury after treatment compared to ungrafted ‘Ole’. The use of transgenic rootstock to transmit desirable traits to the scion was investigated using transgenic virus resistant squash. Nontransgenic watermelon, melon, cucumber, and squash were grafted onto transgenic squash containing the CMV coat protein gene, and leaf samples were analyzed to determine if RNA from the transgene was present in scion leaves. The final area of investigation studied the possibility of transmitting watermelon fruit blotch from infected rootstocks to watermelon scions. Rootstocks of Lagenaria siceraria, Cucurbita maxima, and C. moschata were inoculated with Acidovorax avenae and incubated for 3 days under high humidity. All potential rootstocks showed typical water-soaking symptoms of WFB. A. avenae was found to move within the stem of all three species, indicating a probability for transmission of the pathogen from the rootstock to the scion. Future experiments will investigate the potential for A. avenae to become seedborne on rootstocks.
Resistance of Citrullus colocynthis to Whiteflies and Spidermites
A. Levi1, A. Simmons1, R. Lopez2, C. Kousik1, B. M. Shepard2, M. Jackson1, H. Harrison1, M. Edelstein3, E. Palevsky3, F. Mansour3, E. Lewinshon3, and K. Tadmor3, 1USDA, ARS, U.S. Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC; 2Clemson University, Coastal Research and Education Center, 2700 Savannah Highway, Charleston, SC; 3Agricultural Research Organization, Newe Yaar Research Center, Ramat Yishay, Israel
The B-biotype sweetpotato whitefly (SPWF) [Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae)] and the two-spotted spider mite (TSSM) [Tetranychus urticae Koch (Acari: Tetranychidae)] are serious pests of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus]. U.S. Plant Introduction (PI) accessions representing different groups of Citrullus spp. were examined for SPWF and TSSM resistance in the greenhouse and in insect rearing rooms at the U.S. Vegetable Laboratory, Charleston, S.C., during 2003–2006. SPWF and TSSM were significantly (P < 0.05) less abundant on C. colocynthis PIs compared with C. lanatus var. citroides PIs and watermelon cultivars (C. lanatus var. lanatus). Also in a study we conducted with broad mites [Polyhagotarsonemus latus (Banks)], they were less abundant on C. colocynthis plants compared with watermelon cultivars. Useful sources of resistance to SPFW and TSSM may be present in C. colocynthis due to its wide geographic distribution (from the arid regions throughout North Africa, Middle East, and Southwest and Central Asia) and wide genetic diversity. However, overcoming wide genetic difference between C. colocynthis and cultivated watermelon (C. lanatus var. lanatus) and removing undesired traits of C. colocynthis will be a challenge.
Developing Expressed Sequenced Tags (ESTs) for Watermelon Fruit
Amnon Levi1, Angela Davis2, Pat Wechter1, Alvaro Hernandez3, and Jyothi Thimmapuram3, 1USDA, ARS, U.S. Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC; 2USDA, ARS, Lane, OK; 3University of Illinois at Urbana–Champaign, Biotechnology Center, W.M. Keck Center for Comparative and Functional Genomics, Urbana, IL
A cDNA library was assembled using mRNA of watermelon fruit. The cDNA library was normalized and subtracted by hybridization with leaf cDNA of the same watermelon cultivar (‘Illini Red’). 1046 cDNA clones were sequenced to identify genes associated with fruit development and quality. Of 1046 cDNA clones sequenced, 832 were unique sequences and designated as expressed sequenced tags (ESTs). Of the 832 ESTs, 205 (24.6%) have not been reported in any other plant species. Additionally, 186 ESTs (22.4%) correspond to genes with unknown function, while 441 ESTs (53.0%) correspond to genes with known function in other plant species. These ESTs are mainly associated with primary metabolism, membrane transport, cytoskeleton synthesis and structure, cell wall and cell division, signal transduction, nucleic acid binding and transcription factors, and defense and stress response. Differential expression of the ESTs was examined using microarray analysis. About 200 (24%) of the 832 ESTs showed differential expression during the development and ripening of watermelon fruit. The ESTs were also screened for simple sequence repeat (SSR) motifs. Of 832 ESTs screened, 177 contain SSR motifs. Primer pairs are being designed for these ESTs, and will be used for development of EST-SSR markers and for mapping on a genetic linkage map constructed for watermelon. This study provides valuable information on genes controlling watermelon fruit development and quality.
Hot Topics for Watermelon Research: A Survey of the Industry
Stephen King1 and Angela Davis2, 1Vegetable and Fruit Improvement Center, Department of Horticultural Sciences; 2USDA-ARS, Lane, OK
It is critical for public researchers to address the needs of the industry they work with. While most active researchers believe that they are serving the needs of the industry, an occasional survey can be a useful tool to monitor and prioritize those needs. A survey was compiled after a discussion at the WRDWG meeting in Asheville, N.C., in 2006. The survey was based on problems in the watermelon industry that have the potential for solutions through public research. The survey was sent to watermelon breeders in private industry and handed out to grower participants at the Texas Watermelon Association Meeting, Jan. 2007. The results were compiled for the breeders and growers separately, and a weighted average was compiled. The top priorities for public research identified by breeders included resistance to gummy stem blight (GSB), molecular markers, grafting, powdery mildew resistance (PM), preharvest fruit quality, and watermelon fruit blotch (WFB). Results of grower priorities were more wide-spread, but the top problems included grafting, fusarium, GSB, whiteflies, seedless production, WFB, anthracnose, PM, and health benefits. The weighted mean comparison using combined data showed that the top 10 priorities in rank order were GSB, grafting, fusarium, PM, preharvest fruit quality, molecular markers, WFB, whiteflies, seedless production, and postharvest fruit quality. While this survey was limited to five major seed companies with watermelon breeding programs and only included growers attending the Texas Watermelon Association meeting in 2007, it still provides meaningful insight as to where public researchers should be committing a portion of their research to address needs of the watermelon industry in the United States.
Evaluation of Clean Chip Residual and Composted Poultry Litter as a Growth Substrate for Container-grown Lantana camara
Cheryl R. Boyer*1, Glenn B. Fain2, Charles H. Gilliam1, Thomas V. Gallagher3, H. Allen Torbert4, and Jeff L. Sibley1, 1101 Funchess Hall, Horticulture Department, Auburn University, Auburn, AL 36849; 2USDA-ARS Southern Horticultural Laboratory, Poplarville, MS 39470; 3Department of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849; 4USDA-ARS National Soil Dynamics Laboratory, Auburn, AL 36832
Clean chip residual (CCR) is a forestry industry by-product produced during the harvest of “clean chips” for the paper industry. Clean chip residual is about 49% wood, 9% needles, and 42% bark. Composted poultry litter (CPL), a major waste problem in Alabama, has the potential to provide necessary macro- and micronutrients for enhanced plant growth. However, CPL can potentially harm crops due to high pH and EC. This study evaluated pinebark (PB) and CCR alone and in combination with peatmoss (PM) and CPL. The CPL was composted for 3 days in an in-vessel composter. On 24 July 2006 substrates listed below were amended with 2.27 kg·m−3 dolomitic lime, 0.68 kg·m−3 MicroMax and 6.35 kg·m−3 Polyon (16N–2.6P–10K). Treatments were mixed on a v/v ratio as follows: 100% PB, 3:1 PB:CPL, 3:1 PB:PM, 7:1 PB:CPL, 7:1 PB:PM, 100% CCR, 3:1 CCR:CPL, 3:1 CCR:PM, 7:1 CCR:CPL, and 7:1 CCR:PM. Liners of lantana (Lantana camara ‘New Gold’) were potted into 2.8-L containers and evaluated for 72 days. While differences existed in shoot dry weight, all treatments showed similar or greater growth than 100% PB. The greatest shoot dry weight occurred with 7:1 PB:CPL. Substrate pH ranged from 7.2 to 4.7 for the duration of the study with treatments containing CPL generally higher. By the end of the study, all treatments had similar pH (6.4–7.0). As expected, EC was high in all treatments one day after planting (DAP), but all decreased to acceptable levels by 30 DAP. Treatments containing CPL were highest throughout the study. Tissue nutrient content showed increased N, P, Mn, and Cu in treatments containing CPL. Lantana in CCR with and without CPL grew as well as plants in 100% PB. Plants grown in CPL substrates had reduced growth early in production, but by termination were larger than 100% PB plants. Substrate shrinkage was evident in treatments containing 25% CPL at 70 DAP. For lantana, incorporation of CPL at low ratios may increase plant size with minimal substrate shrinkage.
Optimizing Phosphorus Concentration for Growth of Catharanthus roseus in a Subirrigation and Top Watering System
Andrew D. Cartmill* and David Wm. Reed, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843
Increasing environmental concerns will require commercial container production systems to maximize plant phosphorus (P) utilization and minimize P leaching and runoff into the environment. A model greenhouse experiment was conducted to quantify the optimum water-soluble P concentration for the growth of Catharanthus roseus (L.) G. Don cv. Pacifica Red in a recirculating subirrigation system and a top watering system. Optimum growth response, as measured by shoot dry mass, was 0.94 to 1.83 mM P for recirculating subirrigated plants and 0.96 to 2.22 mM P for top watered plants.
Growth of ‘Red Sparkler’ Celosia using Four Production Systems in a Tobacco Transplant Greenhouse
Carl E. Niedziela, Jr.* and Guochen Yang, Natural Resources and Environmental Design, North Carolina A&T State University, 238 Carver Hall, Greensboro, NC 27411
Plug seedlings of Celosia argentea L. ‘Red Sparkler’ were planted in four production systems (harvest lugs, lay-flat bags, pots, and polystyrene trays) on 5 May 2005. Production systems were randomized in a Latin-square design with four replications of each system. Each treatment plot was 0.7 m × 1.1 m. Planting density was 31 plants/m2. The harvest lugs were 55 cm × 37 cm × 16 cm. The lay-flat bags were 114 cm × 30 cm × 3 cm. The pots were 25-cm bulb pans. The polystyrene trays were 67 cm × 34 cm × 5 cm and contained 32 square cells. All of the containers were filled with the same tobacco germination media. The plants in the harvest lugs, lay-flat bags and pots were irrigated daily with 150 mg kg-1 N from 20N–4.4P–16.6K. The plants in the polystyrene trays were floated on a solution of 150 mg kg−1 N from 20N–4.4P–16.6K. Float solutions were monitored and adjusted weekly for volume and fertilizer concentration. Individual stems were harvested at the appropriate stage of development for market. Stems grown in float trays were shorter than those in lay-flat bags, harvest lugs, and pots. Plant grown in lay-flat bags, harvest lugs, pots, and floats had the greatest to least fresh weights. Plants grown in lay-flat bags and harvest lugs had a greater dry weight than those grown in float trays. Stems from all treatments were shorter than commercially desirable.
In Vitro Culture of Pearlbush
Guochen Yang* and Zhongge (Cindy) Lu, Department of Natural Resources and Environmental Design, North Carolina A&T State University, 238 Carver Hall, Greensboro, NC 27411
In vitro axillary shoot proliferation of pearlbush was achieved using softwood explant materials. This study evaluated different plant growth regulators for their influences on axillary shoot proliferation of pearlbush. Woody plant medium (WPM) with supplements of 3% sucrose and 0.7% agar was used as the basic culture medium, and medium pH was adjusted to 5.8. BA, CPPU, zeatin, or thidiazuron (TDZ) at different concentrations were added to the basic WPM as treatments. All cultures were transferred onto fresh media every 4 weeks and incubated under a 16-hour photoperiod and a photo flux density of 12.8 ± 4.8 mol·s−1·m−2 light provided by cool-white fluorescent tubes at 23 °C. The best shoot proliferation was achieved from cultures containing TDZ.
Response of Container Lotus (Nelumbo) to Five Types of Fertilizers
Daike Tian, Ken M. Tilt, Floyd M. Woods, Jeff L. Sibley and Fenny Dane, Auburn University, Department of Horticulture, 101 Funchess Hall, Auburn, AL 36849
Effects of five types of fertilizers were investigated on the growth of an ornamental lotus (Nelumbo ‘Embolene’) in 28.4-L (7.5 gal) plastic containers filled with a sandy-clay-loam soil. Compared with the control (zero fertilizer), all fertilizers (Urea, Pro•Sol 20-10-20, Miracle-Gro 24-8-16, Miracle-Gro 15-30-15, and Controlled Release Polyon 18-6-12) significantly increased the growth indices: plant height, number of leaves, flowers, propagules, and underground biomass based on application of equal rate of N applied at 10-day intervals. Performance of lotus was better in treatments containing fertilizers with N, P, and K than in the treatment of urea with N alone. Soluble fertilizers are much better than the controlled-release fertilizer Polyon 18-6-12 for lotus growth but the latter prolonged leaf life for about 2 weeks. Higher concentrations of P and K are more beneficial for production of rhizomes or propagules as well as increases in plant height and emerging leaf number. With the exception of flower number, there were no large differences in plant growth indices among treatments of high-frequency-low-concentration and low-frequency-high-concentration of soluble fertilizer Pro•Sol 20-10-20. The type of fertilizer should be selected based on the purpose of production.
Genetic Diversity Estimates and DNA Fingerprint Database for Crapemyrtle Cultivars
Timothy A. Rinehart, USDA-ARS, Thad Cochran Southern Horticultural Laboratory, 810 Highway 26 West, Poplarville, MS 39470
Lagerstroemia, first introduced to the southern United States from Southeast Asia more than 150 years ago, comprises at least 80 known species. Breeding programs over the last 30 years have utilized L. indica, L. fauriei, L. speciosa , L. subcostata, and L. limii as ornamental plants. However, because of a wider range of plant sizes and habits, improved flowering, new flower colors and sizes, disease resistance and increased vigor, the majority of cultivars grown today are hybrids, namely L. indica and L. fauriei hybrids. Once well established, they are extremely tolerant to heat and drought, require little fertilization, and exhibit prolific summer flowers making them a popular woody landscape plant in the South. We recently developed simple sequence repeat (SSR) markers for Lagerstroemia and evaluated their utility for identifying interspecific hybrids. Here we present DNA fingerprints for more than 40 popular cultivars including germplasm released by the National Arboretum. Data represent a comprehensive evaluation of the genetic diversity available and a roadmap for future crapemyrtle breeding. The recently established DNA fingerprint database allows for unambiguous cultivar identification and hybrid verification for resolving true-to-name disputes, plant mislabeling, and patent protection disputes.
Sensory Properties of Puffed Gorgon Nut
M. Paka1, P.C. Coggins1, C.E. Coker2, and P.R. Knight2, 1Garrison Sensory Evaluation Laboratory, Department of Food Science, Nutrition and Health Promotion Mississippi State University, Stone Blvd., Box 9805, Mississippi State, MS 39762-9805; 2Coastal Research Extension Center, Mississippi State University, 1815 Popps Ferry Road, Biloxi, MS 39532
Euryale ferox Salisb. is a perennial aquatic herb belonging to the family Nymphaeaceae/Euryalaceae. The common names are: gorgon plant, water gorgon, fox nut, and prickly water lily. Puffed gorgon nut is obtained from the seed of the gorgon plant. The objective of this study is to develop the sensory lexicon for the puffed gorgon nut. A sensory lexicon to identify and define the appearance, texture (hand and mouth), basic tastes, aroma ,and flavor for E. ferox was created. Eight trained individuals from Mississippi State University generated descriptive terms and references. The descriptive sensory panel received 30 hours of training. Intensity ratings, based on the Spectrum™ Descriptive Analysis Method, were assigned to terms in the lexicon. Thirty-four descriptive sensory attributes were identified to evaluate the appearance, texture (hand and mouth evaluated), basic tastes, aroma, and flavor. This descriptive language will provide a useful tool for categorizing E. ferox, gorgon nut.
Postharvest Evaluations Comparing Primocane- and Floricane-fruiting Blackberries
Colleen McCall-Thomas1, John R. Clark1, and Penelope Perkins-Veazie2, 1316 Plant Science, Department of Horticulture, University of Arkansas, Fayetteville, AR 72701; 2USDA-ARS, SCARL, Lane, OK 74555
Postharvest storage of blackberries from floricanes was compared with primocane berries in a study conducted at the University of Arkansas Fruit Research Substation, Clarksville in 2006. Berries were harvested directly into 1/2 pint polystyrene clamshells affixed with an absorbent liner and refrigerated at 5 °C. After 7 days, the berries were measured for the presence/absence of decay, leakage, softness, and development of red drupes. The values were used to calculate an overall storability score. Results indicated ‘Prime-Jim’®, APF-27, and -40 show comparable overall storage quality for both primocane and floricane berries while APF-41 and -52 showed higher storability for floricane berries. APF-46 showed higher storability for primocane berries. Comparisons of floricane- and primocane-fruiting genotypes using floricane fruits only indicated no significant differences among genotypes for any measurements. However, APF-27, -41, and -52 most closely approached ‘Navaho’ in overall storage quality and numerically surpassed that of ‘Prime-Jim’®. Selections identified with the APF designation are not available commercially.
Effect of Rootstock on Yield Components of ‘Chardonnay’ in Oklahoma
Eric T. Stafne*1, B. Dean McCraw1, William G. McGlynn1, and R. Keith Striegler2, 1Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK 74078; 2ICCEV, University of Missouri, Columbia, MO 65211
Rootstocks can offer benefits such as pest resistance, improved cold hardiness, and tolerance of certain soil characteristics. The objective of this study was to determine if own-rooted ‘Chardonnay’ and ‘Chardonnay’ grafted onto six rootstocks differed in a number of measured yield variables. The plots consisted of Clone 4 ‘Chardonnay’ with six different rootstocks: 1103P, 140R, 3309C, 5BBK, St. George, and Freedom. Rootstock had a significant effect on yield produced by ‘Chardonnay’ when compared to own-rooted vines; however, rootstocks were not significantly different from each other. The overall yield of the own-rooted vines was the lowest, but not significantly different from vines grafted onto 3309C, 5 BBK, and 1103P. Year of harvest was a significant main effect with respect to total yield. The lowest yield occurred in the first year of harvest (2003), with significant increases in 2004 and 2005. Yield in 2006 was significantly less than 2004 and 2005 due to extreme heat and drought conditions during the 2006 growing season, and cold injury during the winter of 2005–2006. Average berry weight and average harvest date were not affected by rootstock, but were by year. A significant interaction of year × rootstock for average cluster weight was observed as well. With additional data, it may be possible to identify rootstocks that are advantageous to Oklahomans growing ‘Chardonnay’.
Effect of Various Soil Amendments on Growth of ‘Reveille’ Southern Highbush Blueberry
Gerard Krewer*1, D. Scott NeSmith2, and Ben Mullinix3, 14604 Research Way, Department of Horticulture, University of Georgia, Tifton, GA 31793; 21109 Experiment Street, Department of Horticulture, Griffin GA 30223; 34601 Research Way, Experimental Statistics Unit, University of Georgia, Tifton, GA 31793
Under southern Georgia conditions, southern highbush blueberries are grown commercially in high organic matter (3% plus) spodic sand soils (of limited distribution), in pine bark bed culture or in sandy soils highly amended with pine bark. The cost of pine bark has increased dramatically with increased demand. Municipal yard waste is a growing environmental problem. In an effort to find low-cost substitutes for pine bark and improve the environment, a 4-year experiment was conducted at UGA Alapaha Station on a loamy sand soil (pH 4.3). Treatments were: 1) soil without amendment; 2) soil amended with milled pine bark (6 inches); 3) soil amended with acidified yard waste (6 inches); 4) a mix of 50% milled pine bark (3 inches) plus 50% acidified yard waste (3 inches); and 5) acidified commercial compost (3 inches). The acidified compost treatment performed poorly; it appeared to hold too much moisture on this marginally wet site for southern highbush blueberries and the pH remained too high. Treatments 2 and 4 produced good plant growth and survival. A mix of milled pine bark and acidified south Georgia yard waste may have potential for significantly reducing costs in southern highbush blueberry production while disposing of an environmental problem.
Impact of Weed Barriers on Newly Planted Peach Trees
D.J. Makus1 and J.L Jifon*2, 1USDA-ARS Subtropical Research Center; 2Texas A&M University, Texas Agricultural Experiment Station, Weslaco, TX 78956
Newly planted (Feb. 2005) ‘Sunracer’ and ‘Sunhome’ nectarine and ‘Tropic Snow’ peach [Prunus persica (L.) Batsch] trees were subjected to conventional and four “organic” weed control methods. Two of the “organic” methods used weed barriers of white plastic (WP) or landscape fabric (LF). A third consisted of a 10-cm-thick mulch of bagasse (Bag). The organic (Org) treatment used cornmeal gluten, flame, and/or mechanical means for weed control. Conventional (Con) weed control was with herbicides. Initial surface lightness (chroma “L” values) of the treatments were WP > Con = Org > Bag > LF (highest to lowest). WP had the highest reflectivity (μmol·s−1·m−2) into the canopy, then Org = Con > LF = Bag (highest to lowest). By the second season, all treatments were similar in reflectivity except WP (highest). Tree growth after 22 months, based on tree volume and trunk girth, and pruning weights were WP = Bag >> LF = Org = Con (greatest to least) . ‘Bag’ had the lowest summer soil temperatures (at 10 and 30 cm) and lowest variation in mean soil temperatures in both summer and winter. Decreasing treatment surface temps. at 1130 hours (10 Aug. 2006) were Bag = LF >> Org = Con = WP. Soil moisture (25–100 cm) and 2006 spring flowering were not effected by weed control method. Precocious fall/winter flowering was higher in the WP and Bag control methods. Material and installation costs were WP = LF = Bag >> Org = Con (highest to least). Time required to manually remove 6 weeks of weed growth was Org = Con > LF ≥ Bag ≥ WP (highest to lowest). The most weed biomass generated during a 6-week summer interval was in Con = Org >> LF = Bag = WP. Fall weed biomass was reduced by a factor of 6× and there were season × control method interactions. Grasses were 85% of weed biomass in the summer (August) and 75% in the winter (November). Bagasse thickness was reduced by 55% after 20 months.
Evaluation of Fruit Cracking and Berry Firmness in Rabbiteye Blueberry
D. Scott NeSmith*, Department of Horticulture, 1109 Experiment Street, University of Georgia, Griffin, GA 30223-1797
Rabbiteye blueberries (Vaccinium ashei Reade) are well suited for conditions in the Southeast; however, problems of fruit cracking, or splitting, in response to excess rainfall during harvest often occur, rendering fresh fruit potential poor. Also, rabbiteye berry firmness is an important parameter related to postharvest quality of fresh fruit, especially for long distant shipping. The objective of this research was to assess various rabbiteye blueberry cultivars and selections for their variation in fruit cracking and postharvest firmness. Fruit cracking data depicted a range of results for various cultivars and selections. The standard cultivars with the lowest degree of fruit cracking were ‘Ochlockonee’, ‘Premier’, and ‘Alapaha’. As with fruit cracking data, the firmness data also indicated a range in firmness values for the various selections and cultivars. The selection T-671 had the highest firmness readings and ‘Premier’ had the lowest. Overall, all rabbiteye material was considered firm, although there were those with a higher degree of firmness. The data suggest a possible correlation between firmness and fruit cracking. That is, those selections that were the most firm tended to be those with higher fruit cracking percentages. Hence, these data suggest that our selecting for the favorable trait of very firm fruit may also be selecting for the negative trait of a tendency for fruit cracking. Additional research in this area is needed to explore this relationship further.
Influence of Cultivar and Shoot Position on Selected Pecan Characteristics
Charles T. Rohla*1, Michael W. Smith2, Niels O. Maness2, and William Reid3, 1Samuel Roberts Noble Foundation Inc., Ardmore, OK 73401; 2Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK 74078; 3Department of Horticulture and Forestry, Kansas State University
The most significant horticultural problem facing pecan producers is alternate bearing. Four pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars were chosen, two with low to moderate and two with severe alternate bearing tendencies, to compare selected characteristics related to irregular bearing. Vegetative and fruit bearing shoots on 1-year-old branches were tagged in October, and flowering was determined the following spring. Shoot and root samples were collected while dormant and analyzed for organically bound nitrogen (N), potassium (K), and nonstructural carbohydrate concentrations. Cultivars with a low alternate bearing tendency had a larger return bloom on the bearing shoots in the terminal position than the other shoot types. Cultivars with a high alternate bearing tendency had a lower return bloom on bearing terminal shoots than vegetative shoots. Bearing shoots in the lateral position usually had a lower return bloom than the other shoot type, regardless of cultivar. Neither root nor shoot N, K, or nonstructural carbohydrate concentrations appeared to be closely related to the alternate bearing characteristics of the four cultivars. The unique characteristic identified for low alternate bearing cultivars was their ability to produce as many or more flowers and flowering shoots the following year on bearing terminal shoots compared to vegetative shoots. In high alternate bearing cultivars return bloom of bearing terminal shoots was suppressed relative to vegetative shoots.
Flowering and Fruiting in Olives under Mild Winters of Coastal Texas
Nasir S.A. Malik, Joe M. Bradford, and Jim Brockington, USDA-ARS Integrated Farming and Natural Resources Research Unit, Weslaco, TX 78596
Commercial cultivation of olives was discouraged for southern Texas because it was assumed that the winters in this area do not provide enough chilling for flowering. Our experiments have demonstrated that olive trees of ‘Arbequina’ could flower and fruit under much mild winter conditions; i.e., without the typical chilling conditions (below 7.2 °C are chilling temperatures, but 2 to 4 °C during the night was considered optimal chilling) that have previously been considered necessary for flowering and fruiting in olives. We proposed that lack of flowering in southern Texas is due more to high temperature during the day (many days reaching 26 °C) than lack of chilling temperatures in the night. Thus ‘Arbequina’, and perhaps other cultivars of olives, should be able to grow and flower and fruit normally in coastal Texas where daytime temperatures do not rise as high as in southern Texas. Initial data from the experiments started last year at different sites along the Texas coastline from Seadrift to Orange show that flowering and fruiting in ‘Arbequina’ olive trees do occur in these regions.
First-year Vigor of Primocane Fruiting Blackberries from the University of Arkansas Breeding Program Grown in Kentucky
Jeremiah D. Lowe*1, Kirk W. Pomper1, John R. Clark2, John G. Strang3, and Sheri B. Crabtree1, 1Atwood Research Facility, Land Grant Program, Kentucky State University, Frankfort, KY 40601; 2Fruit Culture and Breeding, 316 Plant Science Bldg., University of Arkansas, Fayetteville, AR 72701; 3Department of Horticulture, N-318 Agricultural Sciences North, University of Kentucky, Lexington, KY 40546
Primocane fruiting blackberries have the potential to produce a niche-market crop for Kentucky growers from late summer until frost. The objective of this study was to determine the suitability of advanced primocane fruiting (APF) blackberries from the University of Arkansas Fruit Breeding Program for production in Kentucky. In June 2006, six selections of APF blackberries from the University of Arkansas breeding program (APF-27, APF-40, APF-41, APF-42, APF-46, and APF-77) and the commercially available primocane fruiting selections Prime-Jim® and Prime-Jan®, were established at the Kentucky State University Research Farm. Plants were arranged in a randomized complete-block design, with four blocks, including five plants of each cultivar per block (20 plants of each cultivar). On 10 Oct. 2006, survival, total number of canes, total number of flowering/fruiting canes, and vigor (rated visually from 0 to 10) were evaluated in each plot/block for each genotype. First-season survival was excellent for all APF selections. There was a similar number of canes produced in each plot for each genotype; however, the number of flowering canes varied by genotype, with APF-46 producing the most flowering/fruiting canes (15), and APF-27 and APF-77 producing the fewest flowering/fruiting canes (4). Vigor was similar for all genotypes; however, there was a trend for Prime-Jim® and Prime-Jan® plants to be less vigorous than APF selections. First-year survival and vigor were acceptable for APF selections; however, flower, fruiting, and disease resistance characteristics will need to be evaluated over the next 5 years to determine suitability for Kentucky growers.
Weed Control and Economic Considerations of Flame Cultivation in Pawpaw Orchards
Kirk W. Pomper* and Sheri B. Crabtree, Atwood Research Facility, Land Grant Program, Kentucky State University, Frankfort, KY 40601
Pawpaw [Asimina triloba (L.) Dunal] is a new niche tree fruit crop for small farmers in the eastern United States. Flame cultivation offers an organic alternative to herbicide application for the control of grass and perennial weeds and uses a torch-directed flame to kill weeds by causing the plant cells to rupture. The objectives of this study were to determine if 1) flame cultivation with a backpack flamer would control grass/weed coverage around pawpaw trees without damage to trunks and 2) flame cultivation is economically viable. There were four replicate trees in each treatment. On 25 July and 2 and 18 Aug. 2006, a 3-foot area around treatment trees was either subjected to the flaming treatments or weed eating (to a height of 2 inches). On 25 Aug., and 8 and 15 Sept. 2006, regrowth in plots was rated from 1 to 10, with 1 having no grass/weed coverage and 10 having total grass/weed coverage. By 25 Aug. all flame plots had significantly less grass/weed coverage (about 2.25 rating) than control plots (7.75). On 15 Sept., flame treatment plots had increased grass/weed coverage (about 4.75), but less coverage than control plots (9.5). Additionally, trees in either flaming treatment did not display noticeable trunk damage or wilting. Trunk damage will be evaluated again in 2007. Flame cultivation was found to be 2.5 times less expensive than straw mulch (organic) but 15 times more expensive than glyphosate (conventional) for grass/weed control.
Varietal Preference and Vineyard Distribution of Japanese Beetles in a Field Choice Study
Sanjun Gu, Angela Whitehouse, and Kirk W. Pomper*, Atwood Research Facility, Land Grant Program, Kentucky State University, Frankfort, KY 40601
Japanese beetle (JB) is the most widespread and destructive insect pest of many plants, including grapes, in the eastern United States. The objectives of this study were to 1) determine if vineyard position and establishment of JBs over time suggested that all grape varieties and plots were challenged by JBs entering the vineyard, and 2) determine if there was grape varietal preference by JBs in the field. Four wine and 12 table grape varieties were planted in May 2005 in a randomized plot design in the research vineyard of Kentucky State University located in Frankfort. Vines were pruned back to two buds in Apr. 2006 and trained to a bilateral cordon system later in the growing season. Number of JBs on each vine was counted between 9:30 am and noon EST every other day from 21 June to 19 July, throughout the plots of the vineyard. JBs in the vineyard were distributed randomly at the beginning of the study, but were distributed unevenly as the study progressed, resulting in “hot spots” of more JBs with some varieties. Varietal preference of JBs was observed and the wine grape selections examined had greater numbers of JBs than the table grape varieties examined. Based on the number of JBs observed on vines, ‘Chambourcin’ and ‘Himrod’ were preferred by JBs while ‘Edelweiss’, ‘Mars’, ‘Venus’, and ‘Concord Seedless’ were not preferred by JBs.
‘Eudora’, a New Fresh-market Muscadine Grape Cultivar
Stephen J. Stringer*1, Dennis J. Gray2, and James M. Spiers1, 1USDA-ARS Thad Cochran Southern Horticulture Laboratory, Poplarville, MS 39470; 2University of Florida Institute of Food and Agricultural Sciences, Apopka, FL 32703
The Agricultural Research Service, U.S. Department of Agriculture, and the University of Florida College of Agriculture and the Florida Agricultural Experiment Stations announce the naming and release to nurserymen for propagation the muscadine grape ‘Eudora’. ‘Eudora’, tested as CD8-67, was selected at Leesburg, Fla., in 1981 by J.A. Mortensen from a cross between ‘Fry’ and ‘Southland’. Plants of ‘Eudora’ are vigorous and productive, and in southern Mississippi yields are comparable to the most productive cultivars. Flowers are pistillate and produce medium to large, round, firm, purple-skinned berries having high sugar content, excellent eating quality, and flavor. Skins are edible and flavorful and pulp is crisp. Berries contain an average of 3.2 seeds per berry. Testing indicates that skins of ‘Eudora’ possess high concentrations of ellagic acid, a potent antioxidant, greater than that found in many other muscadine grape cultivars. Less than half of ripe berries have wet picking scars, and berries store well under refrigeration with little shrinkage or shriveling. Ripening occurs from late August through late September in the Gulf Coast region. Berries within clusters ripen uniformly and some berry clusters are tight and suitable for cluster harvesting and packaging. ‘Eudora’ has not shown symptoms of Pierce's disease, and has shown good resistance to various fruit rot organisms. ‘Eudora’ is recommended as a fresh-market grape for both dooryard and commercial use. Since flowers of ‘Eudora’ are pistillate, it must be interplanted with other perfect-flowered or self-fertile muscadine grape cultivars to facilitate pollination and fruit set. ‘Eudora’ is readily propagated from softwood cuttings under mist during June and July, and may also be propagated via layerage. A limited supply of 1-year-old potted plants or stem cuttings are available for distribution to bona fide nurserymen, and will be prorated to nurseries if demand exceeds supply. Written requests for plants should be sent to Dr. Stephen Stringer, USDA-ARS Thad Cochran Southern Horticulture Laboratory, P.O. Box 287, Poplarville, MS 39470. Genetic materials of this release will be deposited in the National Plant Germplasm Repository at Davis, Calif., where they will be available for research purposes and commercial development.
Changes in Cell Wall Degrading Enzymes and Scale Firmness during Storage of Onion (Allium cepa L.)
Timothy W. Coolong*1 and William M. Randle2, 11111 Miller Plant Sciences, Department of Horticulture, University of Georgia, Athens, GA 30602; 2202 Kottman Hall, Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH 43210
Three onion lines: Pegasus, MSU4535B, and MBL87-WOPL, representing soft, firm, and very firm bulbs, respectively, were greenhouse grown using standard protocols. After harvest bulbs were stored at 4.0 °C, and 80% RH. Bulb firmness, pectin concentration, polygalacturonase (PGA) and pectin methylesterase (PME) activities were measured at harvest, and after 4, 8, and 12 weeks of storage. Onion scale firmness was affected by variety (P < 0.001) and storage time (P < 0.001). Firmness decreased for all lines over the 12-week storage period. The high dry matter line MBL87-WOPL had the highest average firmness at harvest (425 g) and saw the smallest overall decrease in firmness with an 8% change after 12 weeks. In contrast, the low dry matter cultivar Pegasus had the lowest average firmness readings at harvest (302 g) and a 15% decrease in firmness after 12 weeks. The long-day line, MSU4535B, had a similar 14% decrease in firmness over the 12-week storage period, but had higher average firmness readings at harvest (383 g). Total pectin (uronic acids) were highest in the firmest line, MBL87-WOPL and lowest in the soft, poor storing Pegasus line (P < 0.001). Transmission electron microscopy of onion samples showed that the cell wall/middle lamella region of the high pectin, firm bulb line MBL87-WOPL was thicker and degraded less during storage than in the low pectin, soft Pegasus bulbs. Onion PME activity was affected by onion variety (P < 0.001) and storage time (P < 0.001). MBL87-WOPL consistently had the least PME activity during storage. Onion PGA activity was affected primarily by variety (P < 0.001) and to a lesser extent by storage time (P < 0.05). As was the case with PME, the MBL87-WOPL line had the lowest level of PGA activity throughout the study, while PGA activity in the Pegasus and MSU4535B lines were more variable. This suggests that the initial firmness of bulbs may be related to the amount of total pectin present as firmness increased with total pectin concentration. However, the decrease in firmness levels appeared to be more related to PME and PGA levels in the bulb.
Product Development and Optimization of a Frozen Savory Soy Product
A. Samala, P.C. Coggins, M.W. Schilling, J.C. Wilson, A.N. Pollard, G.R. Duran, A.L. Gandy, R.S. Anderson, and V.K. Royyala, Garrison Sensory Evaluation Laboratory, Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Stone Blvd., Box 9805, Mississippi State, MS 39762-9805
Soy has many healthful benefits as an incorporated nutraceutical. In select foods it could provide many advantages. The objective was to develop a healthy food product with acceptable taste and texture using soy, vegetables, and natural products such as sweet potatoes, carrots, corn, and walnuts. This new product offers the taste and texture of an ice cream, but the low content in sugar and carbohydrates makes it an alternative snack or meal for dietary purposes. A combination of soy protein isolate and non-fat milk solids was used to partially replace the normal cream content of an ice cream while maintaining the textural properties. The treatments were 75% soy protein isolate (SPI) with 25% non-fat dry milk (NDM) and 75% NDM with 25% SPI. The ingredients included soy protein isolate, sweet potato, egg solid, sucralose, Chargrill™ flavor, monosodium glutamate, high concentrate butter flavor, salt, natural banana flavor and citric acid. The regular ice cream preparation process was utilized for this new product with slight modifications. A panel of consumers (n = 50) evaluated the product with positive sensorial results.
Nitrogen Mineralization from Organic Amendments Approved for Use in Organic Transplant Production
Alejandra Sierra*1, Danielle Treadwell1, Eric Simonne1, and Donald Graetz2, 1Department of Horticultural Science, P.O. Box 110690, University of Florida, Gainesville, FL 32611-0690; 2Soil and Water Science Department, P.O. Box 110510, University of Florida, Gainesville, FL 32611-0510
According to the USDA National Organic Standards, organic growers are required to use certified organic vegetable transplants for field-grown vegetables. Crop nutrition in organic production is based mainly on the decomposition of plant- and animal-based organic amendments. Environmental factors such as temperature play an important role in the mineralization and nitrification of nitrogen (N). The rate of ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) release from five organic amendments: blood meal (BLM), feather meal (FM), bone meal (BM), rock phosphate (RP) and potassium magnesium sulfate (SPM); and two controls: an inorganic fertilizer (CON) and potting media with no amendment (NA) was measured during two seasons (spring and summer) and two locations (greenhouse and lab) for 5 weeks. Amendments were mixed with an approved organic potting media at a 1 to 5 ratio and maintained at constant moisture. Temperature of the air was recorded in 15-minute intervals using a data logger and was used to calculate degree days (DD). The NH4+-N and NO3−-N release rates were determined from leachate samples taken every week throughout the study. Temperature, as DD, was different between locations for both seasons (P < 0.05). Increasing temperature enhance the cumulative plant available nitrogen (NH4+-N + NO3−-N) for all treatments (P < 0.05). NH4+-N release rate as a percentage of milligrams of NH4+-N per milligram of N applied in both seasons and locations was FM = BLM > CON > remaining treatments (20.61, 19.75, 18.54 and <4% respectively). The net mineralization rate of all treatments after 5 weeks was 10.95% for summer and 7.64% for spring. This increase is attributed to the higher number of degree days in summer (143) than spring (125). Overall NO3−-N release rate throughout the 5 weeks were relatively low compared to NH4+-N release rates (18.59% for NH4+-N and 12.92% NO3−-N) for all treatments except CON.
Effects of Deficit Irrigation on Water Use Efficiency and Fruit Quality of Drip-irrigated Muskmelon
John L. Jifon*, Juan Enciso, and Bob Wiedenfeld, Texas A&M University, Texas Agricultural Experiment Station, Weslaco, TX 78596
The effects of regulated deficit irrigation (RDI) on leaf gas exchange, water relations, yield, and quality of field-grown muskmelon (cantaloupe cv. Primo) were evaluated during Spring 2005 and 2006. Three irrigation regimes (100%, 75%, and 50% crop evapotranspiration ETc) were established and maintained from full canopy closure to harvest. Leaf water potential (Ψlf) and stomatal conductance declined progressively with deficit irrigation treatment; however, net photosynthesis rate (Pn) was only significantly reduced in plants irrigated at 50% ETc compared to those irrigated at 100% and 75% ETc. Irrigation scheduling based on 75% and 50% ETc resulted in water savings of 17 and 54 mm, respectively, compared to fields irrigated at 100% ETc. Yields were not significantly affected by the 75% ETc irrigation regime, compared to 100% Etc. However, agronomic water use efficiency (lbs yield per m3 of water used) of fields irrigated at 75% and 50% ETc was increased by 7% and 16%, respectively. The results indicate that additional water savings can be achieved by using modified irrigation scheduling strategies such as RDI imposed at the appropriate crop growth stages.
Enzymatic Conversion and Fermentation of Sweetpotato
Paul W. Wilson*1, Don R. Labonte1, Gloria B. McClure1, and Arthur O. Villordon2, 1Horticulture Department, Louisiana State University, Baton Rouge, LA 70803; 2LSU Agcenter Sweet Potato Research Station, 130 Sweet Potato Road, P.O. Box 120, Chase, LA
Sweetpotatoes can be used in the manufacture of ethanol for beverages and alternative fuel. For efficient alcohol production, cultivars will need to have high yields and superior fermentable carbohydrate content. By cooking and treating roots with starch-degrading enzymes, fermentable sugars are produced for subsequent alcohol fermentation. In this study, ‘Beauregard’ and five white-flesh sweetpotato selections were tested for conversion to sugars and fermentation of ethanol by yeast. All of the raw white-fleshed sweetpotatoes had dry matter, AIS, and total sugar values higher than those of ‘Beauregard’, indicating more potential fermentable material. The effects of cooking and exogenous enzyme treatments on starch conversion were not uniform across selections and two cultivars stopped short of complete fermentation of sugars. Unnamed selections 04-6 and 05-112 appear to be suitable for efficient ethanol production due to their conversion characteristics and root yield (T/ha).
Foraging Behavior, Pollinator Effectiveness, and Management Potential of the New World Squash Bees Peponapis pruinosa and Xenoglossa strenua (Apidae: Eucerini)
Blair J. Sampson1, 2, Patricia R. Knight1, James H. Cane3, and James M. Spiers2, 1Mississippi State University, Coastal Research and Extension Center, 1815 Popps Ferry Road, Biloxi, MS 39532; 2USDA-ARS Thad Cochran Southern Horticultural Research Laboratory, 810 Hwy. 26 W., Poplarville, MS 39470; 3USDA-ARS Bee Biology and Systematics Laboratory, Logan, UT 84322-5310
It is remarkable that squash bees in the genera Peponapis and Xenoglossa have importantly contributed to the evolution of New World Cucurbita, but their contribution to agricultural pollination has largely been overlooked by researchers and vegetable producers alike. We developed a series of pollinator surveys as well as pollination and fruit set experiments to gauge the influence squash bees and other abundant bee species exert on aspects of Cucurbita pepo (summer squash) and C. maxima (winter squash) reproductive success and crop performance. Our results indicate that squash and pumpkin crop yields can be improved by strategically planting seed so that host flowering coincides with the greatest overlap in peak foraging of the top two or three pollinator species (Peponapis pruinosa > Bombus impatiens > Xenoglossa strenua). Female squash bees, specifically P. pruinosa with visibly heavy pollen loads, were the most effective pollinators and importantly boosted fruit and seed set. Bees of all species were useful for enhancing fruit size and weight because they encouraged multiple visitation and uniform pollen deposition across stigmatic lobes. Although many genetic and maternal factors also affected crop reproduction and fruit quality, female squash bees were vital to fruit set and yield, and bee populations can be preserved by setting aside undisturbed tracts of soil as permanent nesting sites.
Improving the Potential for Drought and Soilborne Disease Tolerance in Muskmelon by Grafting
John L. Jifon*, Kevin M. Crosby, and Daniel I. Leskovar, Texas A&M University, Texas Agricultural Experiment Station, Weslaco, TX 78596
Two commercial muskmelon varieties (‘Caravelle’ and ‘Primo’) were grafted on Cucurbita and Cucumis rootstocks and grown in fields with a history of vine decline disease caused by Monosporascus cannonballus to determine whether physiological responses of the scions are consistent with predictions of a high capacity for water uptake by the rootstocks. Three Cucurbita (hybrid squashes: 380, 286, and 1330) and six Cucumis (PI 20488, 1207, MR1, PI 212210, PI 124104, and hybrid melon 3105) rootstocks were used. Vines of plants grafted on Cucurbita rootstocks were generally longer than those of nongrafted plants, but this effect was most significant only during the vegetative developmental stages. Leaf water potential (Ψleaf) of plants grafted on Cucurbita rootstocks were consistently higher than those of non-grafted plants, especially during the fruit development stages. Plants grafted on 1207 and PI 12404 also maintained the highest Ψleaf among Cucumis rootstocks. Grafted plants with high Ψleaf also had high leaf stomatal conductance and transpiration rates, indicating ample water supply from the root systems. Maintenance of high Ψleaf by grafted plants indicates that such plants could better tolerate root infection and damage by M. cannonballus without late-season vine collapse.
Learning to Use Controlled-release Nitrogen Sources for Seepage-irrigated Tomato
Kent E. Cushman*1, Eric H. Simonne2, Eugene J. McAvoy3, Kelly T. Morgan1, and Monica Ozores-Hampton1, 12686 SR 29 N, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL 34142; 2Fifield Hall, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611; 31085 Pratt Blvd., Hendry County Extension Office, University of Florida LaBelle, FL 33975
Tomatoes for the fresh market are grown in Florida on approximately 45,000 acres during fall, winter, and spring seasons under intensive irrigation and fertilization management. Controlled-release nitrogen (CRN) sources, N rates, and fertilizer placement were investigated for seepage-irrigated tomato in two trials located in southwestern Florida. Trial 1 compared three CRN sources, Nitamin (granular, methylated urea and derivatives), Multicote (polymer-coated urea), and Agrocote (polymer-coated sulfur-coated urea), to a soluble control (ammonium nitrate) during the winter-to-spring 2006 growing season. Fertilizers were placed in grooves formed into both bed shoulders at rates of 200, 270, and 340 lb/acre N. ‘HA3073’ tomato was used. Trial 2 compared three CRN treatments, applied broadcast in the bed, to an ammonium-nitrate control. The CRN source was a polymer-coated sulfur-coated urea, and treatments were formulations rated to release 80% of N in 2 or 4 months or a 50/50 mixture of 2- and 4-month formulations. Treatments and control were applied at rates of 120, 180, and 240 lb/acre N during the fall-to-winter 2006 growing season. ‘Florida 47’ tomato was used. For trial 1, CRN sources produced significantly lower yields in the medium, large, and extra-large size categories, and total yield, than the control. N rate had little effect on yield. For trial 2, there were no differences in yield among N treatments. Total marketable yield was 2920, 3180, 3220, and 2990 25-lb boxes/acre for the control, 2-month, 4-month, and combination 2- and 4-month CRN materials, respectively. As N rate increased, marketable yield increased in the extra-large size category and for total yield. There were no significant interactions among factors for either trial. Our results showed CRN sources did not perform well in trial 1 most likely because of placement in the bed. Trial 2, on the other hand, tested CRN sources thoroughly mixed with soil during bedding and placed in what is commonly called the “bottom” or “cold” mix. Our results showed CRN sources performed better when incorporated in the bed, equal to that of the control.
Supplemental Foliar Potassium Fertilization Enhances Fruit Quality and Phytochemical Content of Muskmelon
John L. Jifon*1 and Gene E. Lester2, 1Fruit and Vegetable Improvement Center-Texas A&M University, Texas Agricultural Experiment Station, Weslaco, TX 78596 and; 2USDA-ARS Subtropical Research Center, Weslaco, TX 78596
Potassium (K)-mediated processes such as assimilate transport can influence fruit quality attributes such as sweetness, aroma and texture. However, during fruit growth and maturation, soil derived K is seldom adequate to satisfy plant K demand. Supplemental foliar K application has been shown to mitigate this apparent deficiency however, the suitability of potential K salts as foliar sources is still uncertain. In this study, the effects of six foliar K sources [potassium chloride (KCl), potassium nitrate (KNO3), monopotassium phosphate (MKP), potassium sulfate (K2SO4), potassium thiosulfate (KTS), and a glycine amino acid-complexed K, potassium metalosate (KM)] on field-grown muskmelon (Cucumis melo L.) fruit quality were evaluated. Weekly foliar K applications were established starting at fruit set and continuing to fruit maturity. Even though preplant soil K concentrations were very high, supplemental foliar K treatments resulted in generally higher tissue K concentrations. Fruit from plots receiving supplemental foliar K generally had higher soluble solids concentrations (SSC), sugars, and the human wellness compounds—ascorbic acid and β-carotene—than control fruit. However, there were no consistent trends among K sources except for KNO3, which tended to result in poor fruit quality compared to control fruit. The results generally support previous controlled environment findings that supplementing soil K supply with foliar K applications during fruit development and maturation can improve muskmelon fruit quality. Further research is needed to determine the interaction of environmental factors such as soil type on the potential benefits of supplemental foliar K application.
The Melons of Uzbekistan
Richard G. Snyder*1 and David Nagel2, 1Mississippi State University Truck Crops Experiment Station, P.O. Box 231, Crystal Springs, MS 39059; 2Plant and Soil Sciences Department, Mississippi State University, Box 9555, Mississippi State, MS 39762
Eight varieties of melons from Uzbekistan were evaluated to determine growth and yield in Mississippi, as well as market potential. The melons were evaluated in a RCBD with four replications. Seeds were started 19 May 2006, and transplanted 5 June 2006 at the Truck Crops Experiment Station in Crystal Springs, Miss. Spacing was 3 ft between plants, 6 ft between rows, with eight plants per plot. Black plastic mulch (4 ft wide) and drip irrigation were used. Fertilizer was applied as required per soil test. Nitrogen, at the rate of 44 lb/acre, was provided with ammonium nitrate, and potassium, at the rate of 92 lb/acre, was provided with 0-0-60 preplant. The crop was sidedressed with ammonium nitrate at 44 lb/acre. No limestone was required. Standard production practices for melons were used, based on the Southeastern U.S. Vegetable Handbook (Sanders et al., 2006). Harvests were on 31 July, 8 Aug., and 14 Aug.. The melon varieties from Uzbekistan exhibited a broad degree of variability, both among and within varieties. This is most likely due to these being open-pollinated types, saved over many generations of production. ‘Khandalak’ was much earlier than the other varieties, with 68% being harvested on the first of three harvest dates. There were no differences in yield (weight) per acre. However, ‘Khandalak’ had more fruit (number) per acre than all others. This is likely due to its diminutive size (3.6 lb), significantly smaller than six other varieties. ‘Kukcha’ was the largest variety (9.1 lb). While yield was good, quality was generally low. There were wide variations in size, shape, and sugars within varieties; susceptibility to downy mildew and other diseases was very high (a second trial in northern Mississippi was destroyed by high disease pressure); harvest windows were extremely short, with fruit rot very rapid if harvested a day or two late. Sugars were poor to mediocre in all varieties except ‘Kukcha’ and ‘Berddor’, which averaged a Brix of 11. However, due to variability, this high sugar level was not significantly different from half the remaining varieties. These varieties do not appear to be well suited to the climate of Mississippi when grown like cantaloupe. Market conditions demand better uniformity.