Browsing by Author "Jonathan Schultheis, Committee Member"

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    Effects of Crop Rotation on Wireworm (Coleoptera: Elateridae) Populations in North Carolina Sweetpotato Fields
    (2009-08-12) Baumler, Rebecca; Jack Bacheler, Committee Member; Jonathan Schultheis, Committee Member; George Kennedy, Committee Chair
    Studies were conducted to determine the wireworm (Coleoptera: Elateridae) species present in the Coastal Plain agricultural region of North Carolina, effects of crop rotations on the abundance of wireworms, and effects of both crop rotations and wireworm abundance on damage to harvested sweetpotato roots. Wireworm larvae were sampled in the soil using oat baits. Adult wireworms were sampled using yellow sticky traps. In 2005 and 2006, 2,857 total oat baits and 521 total sticky traps were retrieved from insecticide-free portions of 60 total sweet potato fields located throughout the Coastal Plain. Two thousand one hundred twenty-four total larvae and 3,482 total adults were obtained, belonging to eight species. The proportion of total wireworm larvae and adults captured represented by each species, respectively, were: Conoderus amplicollis (0.051, 0.002), C. bellus (0.043, 0.022), C. falli (0.046, 0.020), C. lividus (0.047, 0.033), C. scissus (0.057, 0.056), C. vespertinus (0.627, 0.629), Glyphonyx sp. (0.049, 0.176), and Melanotus communis (0.066, 0.010). Three studies were conducted to determine the effect of preceding crop on the abundance of overwintering wireworms present in fields which may damage any subsequent crop planted. Treatments were defined by the previous year’s crop and were chosen to reflect common crop rotations in the region. A small-plot study was conducted wherein baiting was conducted in spring and early summer with the following treatments: corn, cotton, fallow, soybean, sweet potato, and tobacco. The second was an overwintering study, and involved baiting commercial fields in late fall and early spring. Treatments were: corn, cotton, peanut, soybean, sweetpotato, and tobacco. In the third study, a commercial field survey, baiting was conducted in commercial fields in late spring and early summer. Treatments were: corn, cotton, cucurbit, peanut, soybean, sweetpotato, and tobacco. In the small-plot study, M. communis was the predominant species, and was found in significantly higher numbers following soybean and corn. Mean total numbers of wireworms per bait (all species) were highest following soybean. In the overwintering study, C. lividus was the predominant species, and mean total numbers of wireworms were highest following corn and soybean. In the commercial field survey, C. vespertinus was the predominant species, and mean total numbers of wireworms per bait were highest following corn. The small-plot study and commercial field survey continued into early autumn. Sweetpotatoes were planted in each field used in these studies, and data were analyzed to examine wireworm populations in sweetpotato through the growing season, whether wireworm abundance differed during the growing season or by previous crop, and whether wireworm damage to sweetpotato was related to wireworm abundance during a particular time period or previous crop. The most abundant wireworm species across these studies was C. vespertinus. C. vespertinus larvae were smaller and more abundant after 15 July than earlier in the season, indicating an early-summer generation turnover, and that adults oviposit in sweet potato. C. vespertinus larval abundance was not affected by previous crop. Incidence of wireworm damage to sweet potato was positively correlated with late-season abundance of C. vespertinus.
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    Effects of Plant Growth Regulator and Different Combinations of Soil and Foliar Fertilizer Application on Bell Pepper (Capsicum annuum L.).
    (2010-10-27) Biai, Christopher; Christopher Gunter, Committee Chair; Jonathan Schultheis, Committee Member; Ronald Gehl, Committee Member
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    Evaluation of Sorghum Sudangrass as a Summer Cover Crop and Marketable Hay Crop for Organic, No-till Production of Fall Cabbage
    (2005-07-12) Finney, Denise McKinney; Jonathan Schultheis, Committee Member; Michael Wagger, Committee Member; Nancy Creamer, Committee Chair
    The development of organic and conservation tillage-based vegetable production systems will offer growers in the southeastern United States new economic opportunities and promote resource conservation. The purpose of this research project was to assess the impact of incorporating a summer crop that serves as both cover crop and marketable hay crop in an organic fall vegetable production system. Sorghum sudangrass [Sorghum bicolor (L.) Moench X S. sudanense (Piper) Staph] is commonly cultivated as a forage crop in the Southeast and has the potential to produce abundant biomass, suppress weeds, and decrease soil compaction as a summer cover crop. Field studies were conducted to determine the effects of sorghum sudangrass cutting frequency and biomass removal as hay on cover crop biomass production, weed suppression by cover crop residues, and cover crop re-growth in a subsequent cabbage (Brassica oleracea L. var. capitata) crop under conventional and no-till management. Field and greenhouse studies were undertaken to identify potential negative interactions between cover crop residues and cabbage transplants. Transplant dry weight and head weight of the indicator species, cabbage, were used to assess the impact of cover crop management and tillage system on crop growth and development. Results suggest that a sorghum sudangrass hay crop can be harvested without compromising weed suppressive qualities of the cover crop. In this study, however, the presence of sorghum sudangrass led to reductions in cabbage transplant growth and head weight. Sorghum sudangrass may not be suitable as a cover crop immediately prior to conventional or no-till fall vegetable production due to its propensity to re-grow and allelopathic potential.
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    Genetic and Cultural Management Studies of the Production of Industrial Sweetpotatoes from "Cut Root Pieces".
    (2010-10-06) Bowen, Blake; George Yencho, Committee Chair; PECOTA, KENNETH V. (TC), Committee Member; Jonathan Schultheis, Committee Member; Bryon Sosinski, Committee Member; Mari Chinn, Committee Member
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    Tomato and Pepper Crop Tolerance and Yellow Nutsedge (Cyperus esculentus) Control to Drip Applied Herbicides.
    (2010-10-20) Dittmar, Peter James; David Monks, Committee Chair; Jonathan Schultheis, Committee Member; Garry Grabow, Committee Member; Katherine Jennings, Committee Member; Harold Kleiss, Committee Member