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  • Author or Editor: S. B. Sterrett x
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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.

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New Jersey `Syn 4' asparagus (Asparagus officinalis, L.) was grown on a sandy loam soil to compare plant survival and yield of asparagus grown from crowns and transplants under four irrigation treatments: sprinkler (SPR), surface trickle (ST), subsurface trickle (SST), and no irrigation (NI). While plant survival of crowns was not appreciably influenced by any irrigation treatment, survival of transplants was significantly increased by SST. Total and marketable yields from crowns and transplants were similar in the first harvest season (year 3). However, in years 4 and 5, the yield of crowns was higher than that of transplants. Subsurface trickle increased yield from transplants in years 4 and 5 and increased yield from crowns in year 5. All irrigation methods significantly increased both spear production (spear/ha) and average spear weight. Subsurface trickle irrigation resulted in the largest increase over NI in total yield and spear production.

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Abstract

Belgian endive (Cichorium intybus L.) is an important salad vegetable in Europe (Ryder, 1979; Yamaguchi, 1983). The increasing per-capita consumption of Belgian endive in Europe and in urban areas of the United States, and its high market value (Corey and Whitney, 1987), indicates increasing potential marketing opportunities for this crop. Markets in the United States prefer firm, well-closed (tight), white chicons (blanched, edible head) that, on average, are 10 to 20 cm long and weigh 60 to 110 g (Hill, 1987; Ryder, 1979). Production of the chicons involves growing and harvesting the roots, storing the roots at –1 to 3C for vernalization, and then forcing them (Corey and Whitney, 1987), Blanched chicons are obtained by forcing vernalized roots in soil or hydroponically in the dark.

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Commercial production of bunched broccoli on the Eastern Shore of Virginia has been limited because of shortened internodes resulting in thick, tough stalks. A field study was completed to examine the influence of plant type (transplants or direct seeded), plant population (5800 or 8700 plants/ha), and N application (112 kg/N with zero, one, or two sidedress applications of 40 kg·ha–1) on marketable yield, head diameter, and stem diameter of `Packman' broccoli. None of the measured characteristics improved significantly with sidedress N application. Marketable yield and average head weight were significantly correlated (P = 0.01) to the total number of heads harvested (r = 0.70 and r = –0.91, respectively). More heads were harvested for the high population, direct-seeded treatment and fewer for the low-population transplants. Average stem diameter of transplants was slightly greater than that of direct-seeded broccoli being significant (P = 0.05) in the second and third harvests. However, few stems were of commercially acceptable diameter regardless of treatment combination. Additional evaluation of cultural management strategies and cultivar selection is needed to successfully promote commercial production of bunched broccoli in this growing area.

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A procedure is described for maintaining root quality in a foundation seed program that serves a primarily processing industry. Trueness-to-cultivar root type and color is maintained through hill selections within the prefoundation seed at harvest. Internal color is examined after sprout production, but prior to planting. Each root of the prefoundation seed is lifted and cut. If any sectorial chimeras are visible or the internal color is lighter than expected for that cultivar, all sprouts from that root are discarded. Otherwise, sprouts are planted to generate prefoundation seed. Prefoundation roots not selected by hill selection are given to designated growers for production of foundation seed. Contracts with growers for foundation seed and seed distribution are the responsibility of the Virginia Crop Improvement Assn. (P.O. Box 78, Mt. Holly, VA 22524). Hill selection of `Hayman', a white-skinned, white-fleshed cultivar, over the past 20 years has essentially eliminated strings and nonenlarged roots. Improved root shape and smoothness has resulted in increased regional consumer demand for this specialty crop.

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The progression of internal heat necrosis (IHN) of `Atlantic' potato was studied in seven plantings in two locations (Virginia and New Jersey) over 3 years. The incidence (percentage of tubers with necrosis), severity (rating), and distribution (percentage of 1/8 pieces with necrosis per tuber) of IHN increased with successive harvests, but varied with year and location. Significant but weak linear correlation coefficients were found for the IHN variables of incidence, rating, and distribution with either time in days after planting (DAP), yield, or percentage of tubers >64 mm in diameter. Models were developed using stepwise regression to relate IHN variables with DAP, yield, percentage of large tubers, and various temperature and rainfall measurements. Time (DAP), penalty (DAP to first occurrence of three consecutive days of negative accumulated heat units), and rainfall (1 to 60 DAP) were significant variables in regression models for incidence and rating. While DAP and penalty were significant variables in the regression model for distribution, the variable rainfall was not included in the model. These findings indicate that the potential of IHN in `Atlantic' varies with the growing season, and is influenced by more than one environmental

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A systems approach that included production and economic aspects was used to assess broccoli potential as an alternate enterprise for eastern Virginia. Broccoli yield and head quality were improved with 96,400 plants/ha compared to 64,500 plants/ ha. While target populations for the early harvest were achieved with either transplants or direct seeding, plant establishment was significantly reduced for direct-seeding in the main-season harvest (85% vs. 95% for transplants). Increased cost of production with transplants resulted in reduced enterprise profit (before taxes) in the early harvest, while improved plant establishment and increased yield with transplants resulted in increased enterprise profit in the main-season harvest. The systems approach assessed market price risk through estimated revenue and yield risk, providing the information needed by growers for risk management decisions associated with broccoli as an alternate enterprise.

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An interdisciplinary systems approach was used to explore the potential of fall, fresh-market broccoli as a new enterprise for eastern Virginia. Thirteen cultivars were evaluated in three plantings. Crop value was estimated at each harvest based on weekly market prices. The market window was open from mid-October until late November, with production of 160 cartons/ha, each at 11 kg. However, production of 120 cartons/ha narrowed the window to 2 weeks. Yield of some cultivars exceeded 160 cartons/ha in the first planting; yield of others was below the target production in the second planting. Low yield and low prices during most of the harvest period for the second planting suggests that the optimum harvest season ends in mid- to late November. Problems with poor plant establishment must be addressed before growers can fully capitalize on potential of broccoli as a new enterprise.

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Off-site movement of sediment, nutrient and agricultural chemicals from plasticulture production of green-pack tomatoes on water quality is a serious environmental concern, particularly for the clam aquaculture industry of eastern Virginia. Thus, the development of ecologically sound, economically sustainable cultural management strategies for tomato (Lycopersicon esculentum Mill.) production is needed. Two plantings were made within each of the three tomato harvest seasons [summer, bridge (late summer) and fall] in 1998 and 1999 (one summer crop in 1999). Between-bed treatments included clean culture or pearl millet [Pennisetum glaucum(L.) R. Br.] sown at bed establishment. On-bed treatments included standard plasticulture with fumigation on a 76-cm-wide bed (std), plasticulture without fumigation on a 76-cm-wide bed (std-fum), plasticulture on a 61-cmbed with fumigation (narrow) and organic mulch [wheat straw (Triticum aestivum L.) in 1998; desiccated hairy vetch (Vicia villosa Roth.) in 1999]. Total and marketable yields for the three plasticulture on-bed treatments (std, std-fum and narrow) were similar in 1998 and 1999. Yield was suppressed for the organic mulch on-bed treatments in all but the bridge plantings in 1999. Improved yield with plasticulture treatments and high market price for the summer crop in 1998 resulted in elevated crop value and return to land and management (return) compared to that of organic mulch. The return for later plantings was low, but positive. Return was negative for both bridge and the first fall crops in organic mulch in 1998. Low yields in all treatments and low prices in 1999 resulted in negative to negligible return for on-bed treatments in all but the summer planting using plasticulture. Return was consistently lower with organic mulch compared to plasticulture for the high value summer crop in Virginia with between-bed millet in 1998 and with or without millet in 1999. The use of organic mulch on the beds in this study was not economically feasible for the high value summer crops. Adjustments (desiccation of cover, control of weeds) in cultural management of the between-bed management strategy are needed before large-scale commercial implementation will occur.

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Studies were conducted in 1988 and 1989 to evaluate the influence of planting time and method on plant establishment and yield of fall broccoli. In 1988, plant establishment of direct-seeded broccoli was not improved with application of vermiculite (63 kg/ha). a cross-linked polyacrylamide polymer (17 kg/ha), or both as anti-crustants over the untreated check (37.6%, 32.2%, 24.6%, and 31% of target population, respectively). In 1989, transplants were compared with double-seeding (planting two seeds 25 mm apart). With seed. germination of 55% in the early planting (8 Aug.). plant populations of double-seeding and transplants were similar, but 42% germination of double-seeding in the late planting (28 Aug.) resulted in lower plant populations than from transplants. While yield reflected differences in plant populations, the percentage of marketable heads from transplants was significantly greater (90.6%) than from seedlings (78.9%). These data suggest that broccoli transplants are a viable option when high soil temperatures may be detrimental to seed germination.

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