A field experiment was conducted in Live Oak, Fla., to determine the effect of yellow nutsedge (Cyperus esculentus L.) (YN) density and time of emergence on the yield of direct-seeded squash (Cucurbita pepo L.). YN densities (0, 20, 40, 60, and 100 plants/m2) were established from tubers planted at different times onto polyethylene-mulched beds, so that YN would emerge the same day as the crop or 5, 15, or 25 days later than the crop (DLTC). YN was not controlled after its emergence. The extent of squash yield loss was affected by YN density and time of emergence. When YN emerged the same day as the crop, the yield of squash was reduced by ≈7% (20 YN/m2) to 20% (100 YN/m2). When YN emerged 15 DLTC, crop yield loss was ≈13% at the density of 100 YN/m2>. Regardless of density, YN emerging 25 DLTC did not significantly reduce crop yield as compared to weed-free squash. Thus, in soils with high YN densities (≈100 viable tubers/m2) herbicides and/or other means of YN suppression in squash should be effective for at least 25 days after crop emergence to prevent significant yield loss. If squash yield losses <5% were acceptable, YN control may not be necessary when densities <20 YN/m2 emerge at any time during the squash season or when <100 YN/m2 emerge >25 DLTC. However, YN emerging during the first 15 days of the squash season may produce tubers, which could increase the YN population at the beginning of the following crop season.
J. Pablo Morales-Payan* and William M. Stall
Lynn P. Brandenberger*, Lynda K. Wells, and Bruce B. Bostian
The objectives of this trial were to collect yield and quality data on a fall planted carrot trial. Fifteen different carrot varieties were included in the trial. Plots were 20 feet by 2.5 feet and consisted of two rows of carrots with 15-inch row centers. Plots were replicated 4 times in a RBD. Carrots were direct seeded on 8 Aug. 2003 at 20 seeds per foot. Plots were fertilized with 90 lbs/acre of nitrogen and received overhead water as needed. Yield and quality data were recorded on 5 Dec. 2003. Data included exterior root color, interior root color, percentage of split and forked roots, overall yield, average root length and weight. Exterior root color did not vary significantly for any of the cultivars in the trial, but interior root color varied significantly for several cultivars. `First Class', `Bolero', and `C 7105' had the most distinct differences between the pith and out ring colors as indicated by the interior root color ratings and `Ingot' had the lowest. Interior root color ratings for these four cultivars were 3.8, 3.6, 3.1, and 1.4, respectively. Crispness did not vary for either the initial or second ratings that were recorded. Of potential defects only the percentage of forked roots varied significantly and of these four cultivars had less than 10% forked roots. `Florida', `Kamaran', `Pipeline', and `C 7105' had 5%, 7%, 9%, and 9% forked roots, respectively. `Samantha' had 31% forked roots, the highest percentage recorded in the trial. No differences were recorded for root weight, diameter or length. The three highest yielding cultivars in the trial were `Ingot', `Heritage', and `Neptune' that had overall yields of 24.9, 20.6, and 20.6 tons/acre. `Bremen' recorded the lowest yield in the trial with 13.7 tons/acre.
Elizabeth T. Maynard
Benefits of drip irrigation for jack-o-lantern pumpkins (Cucurbita pepo) in the midwestern United States are not documented. Field trials were conducted on a sandy loam soil to compare yield and fruit size of unirrigated pumpkins (NONE) with pumpkins irrigated when in-row soil water tension (SWT) 30 cm deep reached 20 kPa (HIGH) or 60 kPa (MED). The 2004 trial included two planting methods, direct seed (SD) and transplant, and two cultivars, `Gold Medal' (GM) and `Magic Lantern' (ML). GM typically has larger and more vigorous vines than ML. In 2005 the trial included only SD ML. Rainfall June through August totaled 38.4 cm in 2004 and 28.2 cm in 2005. In 2004 HIGH increased yield 13% compared to NONE (42.1 vs. 37.2 t·ha-1). MED (39.0 t·ha-1) did not differ from NONE. Neither planting method nor cultivar influenced the yield response to irrigation. The effect of irrigation on average weight per pumpkin depended on cultivar. In 2004, ML with HIGH averaged 7.76 kg per pumpkin, 16% heavier than NONE at 6.67 kg. MED averaged 7.17 kg. Irrigation did not affect average weight of GM: HIGH, MED and NONE averaged 12.6, 12.8 and 12.3 kg, respectively. For SD ML, combined analysis of 2004 and 2005 data showed an 18% increase in average pumpkin weight for HIGH vs. NONE (7.94 vs. 6.72 kg), but no significant effect of irrigation on yield (33.6, 29.8 and 28.4 t·ha-1 for HIGH, MED and NONE, respectively). Irrigation did not affect the number of pumpkins produced per hectare for either cultivar in either year. Results suggest that compared to no irrigation, maintaining SWT less than 20 kPA with drip irrigation may lead to 1) yield increase on the order of 10% or less, 2) 16% to 18% increase in average pumpkin weight for ML.
Hiphil S. Clemente and Thomas E. Marler
Trade winds are a widespread horticultural consideration throughout the tropics. Growth and productivity of most horticultural crops are not optimal on sites that are exposed to these chronic, unidirectional winds. We conducted four container studies on an exposed site, using clear plastic or screening material to provide three levels of wind exposure: 0%, 36%, or 100%. Two studies were conducted with direct-seeding, such that seedling emergence and early growth were determined for 7 weeks. Two studies were conducted using 8-week-old nursery plants that had been grown in a protected nursery. These plants were transplanted to the experimental site and grown for 6 weeks. Cultivars were `Known You 1', `Sunrise', and `Tainung 2'. Full exposure to wind reduced height up to 32%, increased root: canopy ratio up to 36% and exhibited no influence or slightly reduced stem cross-sectional area when compared with full protection from wind. Net carbon dioxide assimilation (Pn) was measured on intervals of about 2 h throughout several 24-h periods. Although the daily pattern depended on cultivar and date, the general trend was for Pn to be unaffected by wind from early to mid-morning, and for Pn of the unprotected plants to decline below that of the protected plants throughout the rest of the day. The Pn of plants receiving intermediate protection was highly variable among the cultivars and dates in relation to the protected and unprotected plants. Moreover, dark respiration of the unprotected plants was greater than the protected plants throughout the entire nocturnal period. The primary influence of wind on growth of young papaya seedlings was a shift in biomass allocation in favor of the stem base and roots.
H.C. Wien, B.S. Orenstein, and L.A. Ellerbrock
Although it has been known since the 1930s that long photoperiods and high temperatures hasten bulb formation in onions, the time at which onion cultivars under field conditions in New York start forming bulbs has not been previously reported. In the 1997 and 1998, onion cultivars were seeded in three commercial onion production areas at normal early spring planting dates. In 1998, a time-of-planting study was carried out in Ithaca, N.Y., in which three transplanted crops and three direct-seeded crops were established at monthly intervals beginning at the end of March. Bulb ratios (bulb diameter: neck diameter) were measured at 2-week intervals during the season in all plantings. Initiation of bulbs (assumed to occur 3 weeks before bulb ratio reached 2) was then related to the photoperiod and air temperature up to that point. A comparison of early, mid-season, and late cultivars indicated that bulbs are initiated in commercial plantings in New York at close to the longest day of the year (15.6 h), at a time when mean temperature is still rising. In the time of planting study, delay of planting resulted in fewer days from emergence to bulb initiation and a reduction in growing degree-day accumulation. If planted later than 15 June, some cultivars failed to initiate bulbs, but others, such as `Quantum' and `Winner', initiated bulbs but did not mature them. The results indicate that photoperiod appears to be the primary factor for the initiation of bulbs, but that bulb initiation can be modified strongly in some cultivars by temperature.
William Terry Kelley
Carrots (Daucus carota L.) have become an economically important vegetable crop for Georgia. Currently the harvest season extends from December through May. One possibility for extending the harvest season would be to produce carrots in the cooler mountain area of Georgia during the summer months. This study was undertaken to examine the potential for fresh-market carrot production on Georgia mountain soils and to evaluate which varieties of carrots might be most suitable for this area. Ten commercially available carrot varieties were direct seeded into a Transylvania clay loam soil on 28 May 1999 in Blairsville, Ga. Plots consisted of three twin rows of carrots each 20 feet in length. The twin rows were each three inches apart and there were 20 inches between each set of twin rows. Each plot was replicated four times. Base fertilizer of 20 pounds of nitrogen, potassium, and phosphorous were incorporated into the plots prior to seeding. Sidedress applications of 15 pounds each of N, P, and K were applied at 3-week intervals throughout the season. Recommended pest control practices were applied. A three-foot section of the center twin row was harvested on 23 Sept. 1999. The varieties `Pacific Gold' and `Topnotch' produced the highest marketable yield; however, all yields were below acceptable levels. Percent marketability was <60% for all varieties. Percent stand was extremely variable due to variability in seed size. All carrots had severe nematode damage although a nematicide was used preplant. The length of season for spring-planted carrots was too long for the life of the nematicide at the rate and method applied. Late summer–planted carrots would likely be a more viable option for this area.
Dan Drost, Rich Koenig, and Terry Tindall
Nitrogen (N) losses can be substantial in furrow-irrigated onions (Allium cepa L.). Polymer-coated urea (PU) may reduce N losses and result in an increase in productivity. In this study, we investigated the effects of different rates and blends of urea and PU on onion yield and N use for two cropping seasons. Nitrogen was applied at 112, 168, and 224 kg·ha-1 as PU or urea. In addition, three PU/urea blends equal to 224 kg·ha-1 of N were compared. Plant growth and N concentration, soil nitrate concentrations, and bulb yield were evaluated each year. Onion yield decreased by 95 Mg·ha-1 for each 25% increase in the proportion of urea in the fertilizer blends. Reducing the N rates from 224 to 112 kg·ha-1 had minimal effect on bulb yield when all the fertilizer was supplied by urea. A reduction of N applied from 224 to 168 kg·ha-1 had little effect on yield, although a further reduction to 112 kg·ha-1 did significantly reduce bulb yield when the entire N was supplied from PU. Nitrogen source and rate had no effect on bulb maturity and only minor effects on leaf area and storage potential. Soil sampling indicated that more N was retained in PU-treated onion beds than in urea-treated beds, which improved nitrogen use efficiency. In addition, N use efficiency improved when there was more PU in the blend and when PU was compared with urea at the same rate. We conclude that the use of PU can dramatically improve N use efficiency and productivity in direct-seeded onions.
Heli Cain Nunez-Grajeda and Sergio Garza-Ortega
Cushaw squash is cultivated in northwest Mexico mainly during the fall and to a lesser degree in the spring season, in which a lack of fruit production in experimental and commercial materials has been observed. This work was done to test 12 lines, 16 hybrids and six landraces regarding fruit and seed weight, flesh color, and soluble solids content (SSC) in both spring and fall seasons in year 2002. Estimates of fruit and seed yield were done. The crop was established by direct seeding at 0.5-m spacing between plants, on both sides of furrow-irrigated beds measuring 15 m long and 4 m wide. In the spring, fruit weight changed from 2.7 to 4.7 kg and seed weight from 17 to 118 g/fruit; fruit yield varied from 3.2 to 38.8 t·ha-1 and seed yield from 18 to 1131 kg·ha-1. Thirty-two percent of the genotypes, including lines and hybrids, but not landraces, were fruitless. SSC and flesh color had values from 4% to 7.5% and from 5.22 to 6.94 Y, respectively. For the fall culture all the genotypes showed good fruit set. Fruit weight in this season changed from 0.8 to 3 kg and seed weight from 22.3 to 97 g/fruit; fruit and seed yield varied from 4 to 28 t·ha-1 and from 135 to 923 kg·ha-1, respectively. All of the landraces were severely infected with squash leaf curl virus and had very low yields. SSC and flesh color, in this season, had values from 3.6% to 10.4% and from 5.1 to 7.94 Y, respectively.
Olivia Riffo and Monica Ozores-Hampton
The nursery industry in Florida relies entirely on peat as a major component in potting soil. Escalating peat costs are a major concern, so alternative media are attractive in Florida. The objectives of the project were to study the feasibility of using food waste compost (FWC) to replace peat in different annual ornamental crops. The experiments were conducted in Spring 2004 at the University of Florida/SWFREC Immokalee, Fla. The crops basil (Ocimum basilicum L.), marigold (Calendulaofficinalis L.), and periwinkle (Vincarosea L.) were grown in mixes of FWC. The treatments were: 1) 100% FWC; 2) 60% FWC, 25% vermiculite, 15% perlite; 3) 30% FWC, 30% peat, 25% vermiculite, 15% perlite; and 4) 0% FWC, 60% peat, 25% vermiculite, 15% perlite, by volume. Basil `U.H' was direct seeded; marigold and periwinkle were transplanted (5 cm tall) in pots (2 inches). All treatments received 4 g per pot of Osmocote (19-6-12) for 4 months. Percentage of basil germination and biomass were higher in mixes with 60% and 30% FWC as compared with 100% FWC and the control. Lower basil biomass in the control media was due to high weed biomass grown in the peat control media. There were no differences in biomass and number of flowers per plant among marigold treatments. But, periwinkle dry biomass and number of flowers per plant were higher in the control and 30% FWC than in 60% and 100% FWC, indicating a negative effect of FWC in periwinkle. It can be concluded that FWC may become a viable alternative to replace peat in basil and marigold when included in potting mixes between 30% and 60% by volume, but a negative effect was reported in periwinkle production.
Jeanine M. Davis and Jacqulyn T. Greenfield
Seventeen North Carolina farmers received $5000 grants to grow medicinal herbs as part of a research study to determine the economic feasibility of producing herbs in different regions of the state, including producing the quality and quantity of medicinal herbs required by the industry at a price that is competitive in a global market. With the help of five buyers in the natural products industry, four medicinal herbs were selected to be grown: California poppy, dandelion, Echinacea purpurea, and valerian. The growers experimented with new crops, learned new production methods, and adapted existing methods and equipment to these crops. These growers were also introduced to new markets and made connections with buyers, statewide and nationally, in an industry that can be difficult to enter. Growers were responsible for keeping detailed records of production, harvest, and postharvest handling. To produce a marketable crop in 1 year, some of the growers started seedlings in their greenhouses, while others direct seeded into the field. With the natural products industry moving toward a nonchemically grown product, growers in this project had to produce their crop without pesticides. Weed pressures were the biggest challenge to most of the growers. Prior to harvest, bioactive constituents were tested on the dried raw material to see if levels met buyers' requirements. Other testing methods determined percentage of ash, moisture content, microbial limits, and heavy metal accumulation. For postharvest handling, tobacco farmers who had drying facilities experimented with different temperature regimes to produce a uniformed dried material. Buyers and growers were then introduced to each other to complete the sale of goods.