Browsing by Author "Alan York, Committee Member"

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Atrazine Efficacy and Interactions with Poultry Litter
(2003-04-22) Morrow, Karen Steele; Richard McLaughlin, Committee Chair; Alan York, Committee Member; Robert Mikkelsen, Committee Member
The purpose of this study has been to investigate interactions between soil, poultry litter and atrazine (2-chloro-4-ehtylamino-6-isopropylamino-1,3,5-triazine). Consideration was given to atrazine efficacy, leaching and sorption when applied in conjunction with poultry litter. Application of recommended amounts of poultry litter increased the average mass of oats and soybeans and the application of atrazine increased soybean chlorosis and oat fatality. Leachate from pots that had atrazine applied in conjunction with composted and weathered poultry litter was collected and analyzed for atrazine, DIA (2-chloro-4-ethylamino-6-amino-1,3,5-triazine) and desethylatrazine or DEA (2-chloro-4-amino-6-isopropyl-amino-1,3,5-triazine), using solid phase extraction and GC-MS. Greater amounts of poultry litter significantly increased the amount of leachate from the pots and the amount of leached atrazine was dependent on leachate volume. The sorption of atrazine onto soil and poultry litter was measured through a batch adsorption experiment and Freundlich (Kf) adsorption constants were calculated. Stockpiled litter at the recommended rate (1X) had the lowest Kf (0.68) followed by soil (1.06), 3X stockpiled litter and soil (1.17), 1X weathered litter and soil (1.20), 3X weathered litter and soil (1.93), stockpiled litter (17.65), and weathered litter (33.76).
Improving Cotton Production Margins through Management Decisions and Use of New and Standard commercial Products to Improve Quality and Profits
(2005-09-09) Nuti, Russell C; Randy Wells, Committee Co-Chair; David Jordan, Committee Member; Alan York, Committee Member; Art Wollum, Committee Member; Keith Edmisten, Committee Co-Chair
Cotton (Gossypium hirsutum L.) is a perennial plant managed as an annual crop to optimize yield and fiber quality while managing inputs to maximize profit. Transgenic improvements have simplified cotton production. Resistance to the non-selective herbicide glyphosate and in-plant production of Bacillus thuringiensis (Bt) endotoxin are two such advances. Cultural practices including use of mepiquat chloride (MC), and optimizing planting date contribute to crop uniformity and decrease risk involved with environmental stresses. Comparisons between conventional and transgenic weed and insect management systems, optimal and late planting dates, overhead sprinkle irrigation and drip irrigation, and use of MC were evaluated. Optimal-planted cotton had better yield than cotton planted late. Mepiquat chloride did not always provide an advantage, however never caused an undesirable response. At times, cotton plants treated with MC showed improved micronaire, compensation for boll loss, and earlier maturity. Broadcast glyphosate at the eight-leaf stage reduced yield of optimal-planted cotton in 1 of 3 years and 2 of 3 years in late-planted cotton. Glyphosate contact after the four-leaf stage in 2 of 3 years shifted the majority of bolls above node 10. Lint yield results were variable between overhead sprinkle and drip irrigation systems. Mepiquat chloride did not affect yield in irrigated cotton, however did control plant height, and improve fruit retention and cotton maturity. Non-labeled glyphosate applications reduced maturity in each irrigation system in 1 of 3 years. Cotton injury caused by conventional herbicides resulted in yield loss and poor returns compared to glyphosate systems. Early-season weed competition from low input herbicide programs caused cotton biomass reduction. High costs of conventional herbicide programs offset the available profit margin compared to glyphosate systems when yields were similar. Glyphosate systems provided excellent control of all weed species, while conventional herbicides gave acceptable control in most cases. Glyphosate resistant cotton cultivars with had better yield and returned more profit than the same cultivars treated with conventional herbicides.
Reducing Costs and Optimizing the Timing of Agronomic Inputs for Cotton (Gossypium hirsutum L.) in North Carolina.
(2009-10-01) Collins, Guy David; Alan York, Committee Member; Jack Bacheler, Committee Member; Keith Edmisten, Committee Chair; Randy Wells, Committee Member
Cotton (Gossypium hirsutum L.) grown in North Carolina requires intensive management for achieving optimal yields in an early-season environment. Recent increases in production costs require cotton producers to adopt practices that allow yield potential to be reached, while reducing input costs or optimizing the timing of agronomic inputs. Six experiments were conducted in North Carolina from 2006 to 2008 to investigate various production practices that could potentially reduce production costs and to define optimal timings of agronomic inputs. The first experiment investigated precision application of in-furrow insecticides for cotton planted in a hill-dropped configuration. The second experiment investigated application rates and timings of mepiquat chloride (MC) for cotton grown in conditions that promote excessive vegetative growth. The third experiment investigated the effects of MC applied at various rates and timings on the correlation (regression) between two techniques for measuring light interception and canopy coverage: the light quantum sensor method and the overhead digital imagery method. The fourth experiment investigated the effects of MC applied at physiological cutout, in terms of defoliation, regrowth, maturity, and yield. The fifth experiment investigated the effects of preconditioning defoliation treatments for tall cotton portraying dense canopies which improve standard defoliation practices and the timeliness of harvest. The sixth experiment investigated the effects of ethephon rate in defoliant mixtures on harvest date, with regard to defoliation timing and prior MC treatment.