The effect of crop rotation was investigated on the efficacy and the economics of various insecticide strategies for Colorado potato beetle (CPB) control in potatoes (Solanum tuberosum L.) in 1995-96. These included broad-spectrum insecticides and biorational (environmentally friendly, naturally occurring) combinations that targeted specific CPB life stages. CPB pressure was greater in the nonrotated than the rotated plots. Although all materials gave better CPB control than the check, significantly more spray applications were required to reduce CPB numbers below treatment thresholds in the nonrotated plots than the rotated plots in both years. Overall yields and economic returns were significantly greater in the rotated plots in 1995. Efficacy of insecticide strategies varied, with little defoliation and few CPB larvae found in the imidacloprid treatment in 1995 and 1996. All insecticide strategies except endosulfan resulted in significantly higher estimated returns to management than the untreated check; the greatest returns occurred with permethrin and cryolite. No yields or returns could be obtained in 1996 due to excessive rainfall before harvest. These results indicate that yield and the cost of the insecticide strategy should be considered as well as insecticide efficacy in developing an effective integrated pest management program.
John Speese III and S.B. Sterrett
Eleni Tsantili, Miltiadis V. Christopoulos, Constantinos A. Pontikis, Pantousis Kaltsikes, Chariklia Kallianou, and Michalis Komaitis
The effect of three preharvest sprays with water or 58.5 mm calcium chloride (CaCl2) on texture and other quality attributes was investigated in ‘Konservolia’ olives harvested at the black-ripe stage and measured after 1 and 15 days of storage in air at 10 °C with 85% relative humidity. Effects on fruit calcium (Ca) and magnesium (Mg) concentrations during the period of spray applications were also studied. Concentrations of Ca, Mg, and chlorophyll and photosynthesis rate in leaves were measured on the day of final fruit harvest. No foliar or fruit toxicity was observed. In leaves, Ca sprays increased Mg but did not affect Ca and chlorophyll concentration and photosynthesis rate. In fruits, Ca sprays prevented the gradual decrease in Ca concentration that occurred in untreated fruits and maintained Mg at constant levels during ripening on the tree but did not affect fruit size and oil content as measured 1 day after storage. Ca-treated fruits were firmer with lower soluble pectin (SP) concentration and higher calcium pectate (CaP) than controls in both storage days, whereas the protopectin levels were similar in all fruits. Results showed positive linear correlation between Ca concentration and either firmness or CaP, whereas that between Ca and SP was negative as found in fruits stored for 1 day. Fruit production rates of carbon dioxide and ethylene, L* and chroma (C*) of peel, and hue angle (h°) of flesh were unaffected either by Ca treatment or storage time. Ca treatment did not affect fruit weight loss, the decreases in peel h° and flesh L*, but increased flesh C* during storage. The results indicate positive effects of preharvest calcium sprays on olive firmness without any negative effect on fruits or leaves.
Michael R. Evans, Harold F. Wilkins, and Wesley P. Hackett
Exogenous foliar spray applications of gibberellic acid (GA3) applied at 7- or 14-day intervals providing 50 or 125 μg per plant inhibited long-day (LD) floral initiation in poinsettia [Euphorbia pulcherrima (Willd. ex. Klotzsch)]. Periodic application of GA3 resulted in an additional number of nodes being produced by the plant before floral initiation equivalent to the number of nodes over which GA3 was applied. Further, GA, application eliminated the nodal position dependence of the long-day node number (LDNN) of axillary meristems observed in control plants. It was concluded that GA3 application inhibited the inclusion of nodes into the LDNN count and thus inhibited ontogenetic aging of the meristem. Exogenous application of GA, also inhibited LD floral initiation, while application of GA4 had no effect. Application of GA7 delayed LD floral initiation, but plants did initiate cyathia by the termination of the experiment. All gibberellins increased the average internode lengths similarly. The gibberllin-biosynthesis inhibitors chlormequat and paclobutrazol had no effect on LD floral initiation when applied as single or multiple foliar sprays or as soil drenches, although heights and internode lengths were reduced by application of the inhibitors. The LDNN of plants grown at 31C was significantly higher than of plants grown at 16, 21, or 26C. All plants eventually initiated cyathia regardless of temperature. When plants were grown under a range of day/night temperatures, an increase in the LDNN occurred only when plants were grown at 31C during the day. Chemical names used: 2-chloroethyl-trimethyl-ammonium chloride (chlormequat); (+/-)-(R*,R*)-β -(4-chlorophenyl)methyl-α -(1,1-dimethylethyl)-1-H-1,2,4-triazole-1-ethanol (paclobutrazol).
Laurie Hodges, Entin Daningsih, and James R. Brandle
Field experiments were conducted over 4 years to evaluate the effects of antitranspirant (Folicote, Aquatrol Inc., Paulsboro, N.J.) and polyacrylamide gel (SuperSorb, Aquatrol Inc., Paulsboro, N.J.) on early growth of transplanted muskmelon grown either protected by tree windbreaks or exposed to seasonal winds. A randomized complete block design (RCBD) with split plot arrangement was used with wind protection (sheltered and exposed) areas as the main treatment and use of an antitranspirant spray or gel dip as subtreatments. Based on destructive harvests in the field, treatments and subtreatments did not affect dry weight or leaf area index in the first 2 years. Specific contrasts, however, showed that gel application significantly increased fresh weight, dry weight, and leaf area index over that of the untreated transplants whereas the spray application tended to reduce these factors during the first 3 weeks after transplanting. Significant differences between gel and spray subtreatments disappeared by 5 weeks after transplanting. Shelterbelts ameliorated crop microclimate thereby enhancing plant growth. Significantly, wind velocity at canopy height was reduced 40% on average and soil temperatures were about 4% warmer in the sheltered plots compared to the exposed plots during the first 5 weeks post-transplant. Muskmelon plants in the sheltered areas grew significantly faster than the plants in the exposed areas in 2 of the 3 years reported, with the 3-year average fresh weight increased by 168% due to wind protection. Overall transplanting success and early growth were enhanced the most by wind protection, followed by the polyacrylamide gel root dip, and least by the antitranspirant foliar spray. We conclude that microclimate modification by wind speed reduction can increase early muskmelon plant growth more consistently than the use of polyacrylamide gel as a root dip at transplanting or the use of an antitranspirant spray. A polyacrylamide gel root dip generally will provide more benefit during early muskmelon growth than the use of an antitranspirant spray.
Amy Lynn Bartel and Terri W. Starman
Angelonia angustifolia `Blue Pacific', Asteriscus maritimus `Compact Gold Coin', and Heliotropium aborescens `Fragrant Delight' are three vegetatively propagated species of annuals. The objective of this study was to find which plant growth regulator chemicals could be used to control height and produce compact, well-branched, flowering plants. The plants arrived as rooted plugs and were transplanted to 10-cm plastic containers. When the roots of the transplanted plugs reached the edge of their containers, 15 days after transplanting, the plant growth regulator chemicals were applied. Five different chemicals were used in spray applications at two rates measured in mg/L: ancymidol at 66 and 132; daminozide at 2500 and 5000; paclobutrazol at 20 and 40; ethephon at 500 and1000; and uniconazole at 10 and 20. One drench application of uniconazole at 1 and 2 mg/L and one control (water spray) were also used. Total plant height, plant width, flower number, node number, stem length, internode length, and numbers of days to visible bud were recorded. Ancymidol at both rates caused stunting and flower distortion in asteriscus; however, it was not effective on angelonia or heliotrope. Paclobutrazol and uniconazole sprays were ineffective in controlling height on all three species. Ethephon at both rates was effective in controlling height, and producing well-branched plants in all three species, yet it caused a delay in flowering. Uniconazole drench at both rates was also effective in controlling height but caused stunting. In general, daminozide at 5000 mg/L was most effective in controlling foliage height without a delay in flowering or decrease in flower size or number in all three species.
Christopher S. Cramer and Mark P. Bridgen
Mussaenda, a tropical ornamental shrub developed in the Philippines is being examined as a potential greenhouse potted crop in the United States. Showy sepals of white, picotee, pink or red and fragrant, yellow flowers make Mussaenda an attractive patted plans however, the profuse upright growth habit of some Mussaenda cultivars is undesirable for pot plant culture. With this in mind experiments were conducted to determine the effects of three growth regulators at two concentrations each, as well as the application method and the number of applications on Mussaenda plant height.
Three growth regulators, daminozide (B-Nine), ancymidol (A-Rest), and paclobutrazol (Bonzi) were applied at two commercially recommended rates and two application methods (spray or drench). The treatment were daminozide at 2500 ppm and 5000 ppm (spray), ancymidol at 33 and 66 ppm (spray) and at 0.25 and 0.50 mg/pot (drench), and paclobutrazol at 25 and 50 ppm (spray) and at 0.125 and 0.25 mg/pot (drench). In subsequent experiments, the same growth regulators were applied with an increase in concentration and either two or three applications. The treatments were daminozide at 5000 ppm (spray), ancymidol at 66 and 132 ppm (spray) and at 0.50 and 1.0 mg/pot (drench), and paclobutrazol at 50 and 100 ppm (spray) and at 0.25 and 0.50 mg/pot (drench).
The most attractive potted plants were produced with two applications of daminozide at 5000 ppm or two applications of ancymidol at 0.5 mg/pot (drench). Higher concentrations or additional applications excessively reduced plant height. Three spray applications of 132 ppm ancymidol also produced an attractive potted plant. Paclobutrazol sprays or drenches at any concentration or application number were ineffective for reducing Mussaenda `Queen Sirikit' plant height.
Stephen C. Myers, Amy T. Savelle, D. Stuart Tustin, and Ross E. Byers
Partial thinning of peach (Prunus persica L. Batsch) during bloom to 50% of the necessary level by hand, and followed by adjustment hand thinning at 42 days after full bloom (DAFB) was compared to a similar degree of thinning accomplished entirely at 42 DAFB by hand. Partial flower thinning altered the distribution of fruit by diameter, increasing the percentage of large diameter (≥62.0 mm) fruit harvested compared to unthinned trees or trees thinned entirely at 42 DAFB. Although shoot number per limb was not altered by thinning time, the distribution of shoots by length was affected, increasing the percentage of long shoots (≥20.0 cm). Compared to unthinned trees and trees thinned at 42 DAFB, partial flower thinning increased the subsequent development of flower buds per shoot and the number of flower buds per node. Number of flower buds on the proximal five nodes of shoots 15.0-30.0 cm in length was increased, although not on shoots 5.0-7.0 cm in length. Additional trials established that airblast spray application of AMADS was effective in achieving a similar level of thinning as that accomplished by partial flower thinning by hand in previous experiments. The degree of flower removal exhibited a linear response to chemical concentration. Fruit diameter on chemically flower-thinned trees was greater at adjustment thinning time, when compared to trees thinned by hand at 42 DAFB only. Distribution of fruit at harvest indicated a larger percentage of fruit >65.0 mm in trees which received partial flower thinning in comparison to trees thinned at 42 DAFB only. As a result, overall crop value was increased, based on the commercial processing peach price structure at the time of harvest. Chemical name used: 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS)
Mustafa Özgen, Karim M. Farag, Senay Ozgen, and Jiwan P. Palta
Highly colored cranberries are desired for both fresh and juice markets. Berries accumulate more color when allowed to stay on the vines longer. However, early fall frosts often force growers to harvest before the fruit has reached its optimal color. This is especially true for the berries under the canopy. No product is currently available for grower to accelerate the color development in cranberries. Result from recent studies suggests that a natural lipid, lysophosphatidylethanolamine (LPE), can accelerate color production in fruit and, at the same time, promote shelf life. LPE is a natural lipid and is commercially derived from egg and soy lecithin. The influence of LPE on anthocyanin accumulation and storage quality of cranberry fruit (Vaccinium macrocarpon Ait. `Stevens') was studied. Cranberry plants were sprayed with LPE at about 4 weeks before commercial harvest at multiple locations. Experiments were conducted in 1997, 1998 and 1999. Fruit samples were taken at 2 and 4 weeks after spray application to determine the changes in the fruit color. Plots were wet harvested using a standard commercial method and stored in a commercial cold storage facility. Marketable fruit were evaluated at 1 and 2 months after cold storage to determine effect of LPE on shelf life of cranberries. In general, a preharvest application of LPE resulted in a 9% to 27% increase in fruit anthocyanin concentration compared to the control. LPE treatments also resulted in 8% to 12% increase in marketable fruit compared to the control following cold storage. Influence of LPE on fruit quality was more apparent after 1 month of storage. These results are consistent with the observed effects of LPE on tomatoes. Interestingly ethanol application also enhanced storage quality. Our results suggest that a preharvest application of LPE may have the potential to enhance color and prolong shelf life of cranberry fruit.
Amir Rezazadeh, Richard L. Harkess, and Guihong Bi
Red firespike (Odontonema strictum) is an ornamental shrub with potential for use as a flowering potted plant due to its dark green foliage and attractive red flower spikes. To stimulate branching and improve quality of red firespike, foliar spray applications of dikegulac sodium (DS) and benzyladenine (BA) and hand pinching were evaluated across two seasons (Spring and Summer 2014). There were three pinching treatments: one, two, or three pinches. Plant growth regulators (PGRs) were applied at 400, 800, 1600, or 2400 ppm DS or 600, 1000, 1250, or 1750 ppm BA. Both studies included an untreated control. Red firespike treated with all concentrations of BA and 1600 and 2400 ppm DS had increased branching compared with the control, except 1000 ppm BA in Expt. 1. Pinching did not affect the number of branches. Dikegulac sodium at 1600 and 2400 ppm and all concentrations of BA resulted in shorter plants than the control. Phytotoxicity was observed in plants treated with 1600 or 2400 ppm DS. In both experiments, DS at 1600 and 2400 ppm had the least plant dry weight compared with the control. Treatment with BA at 1750 ppm resulted in greatest leaf area compared with control. Dikegulac sodium at 800 ppm increased the number of flowers compared with control. Pinching and BA did not affect number of inflorescences. All concentrations of BA and DS delayed flowering, except 1000 ppm BA. Plants treated with 800, 1600, and 2400 ppm DS had shorter inflorescences compared with control plants. Benzyladenine decreased the length of the inflorescence at high concentrations, 1250 and 1750 ppm. Pinching treatments did not affect inflorescence length.
Mark E. Uchanski and Adam Blalock
In the desert southwest of the United States, cayenne pepper (Capsicum annuum L.) is an important crop. It is used in the production of hot sauce mash, the precursor to many hot sauces. Because hand harvest is currently required to accommodate staggered crop development, more uniform maturity is desired to facilitate mechanical harvest to decrease labor costs. This study was performed over 3 years (2009–11) and in two locations in southern New Mexico, resulting in five unique year/location scenarios (environments). Four timings of ethephon (0.56 kg a.i./ha) spray applications were evaluated for their potential to increase red cayenne cv. Mesilla yields and percentage of red pods. If yield increases and pigmentation improvements occur, ethephon may facilitate a once-over mechanical harvest. Ethephon was applied once at four key cayenne growth stages based on heat units accumulated after planting (HUAP): 1400 HUAP (late June to early July), 1800 HUAP (mid-July), 2800 HUAP (late August to early September), and 3100 HUAP (mid- to late September). Application timings corresponded to early bloom, peak bloom, late physiological maturity of plants, and preharvest, respectively. A non-sprayed control was also included. Fresh red, green, and non-marketable pod weights were recorded for each treatment in a once-over simulated machine harvest in October and analyzed for statistical differences. Mid- to late-season (2800–3100 HUAP) ethephon treatments significantly decreased undesirable green pod yield and, therefore, increased red pod percentage in four of five environments. Although a red pod yield increase was only observed in one environment (a drip-irrigated plot in 2010), there were no negative impacts on red pod yield in any environment resulting from ethephon application. In addition, pepper quality (yield of unmarketable pods) was not significantly reduced by ethephon. Previous work has focused on increasing red pod yields with mixed results. The results show that ethephon may synchronize cayenne pepper red fruit maturity necessary for mechanical harvest and reduce the labor involved in removing green pods before processing.