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LOGO: Journal of Cotton Science


Cotton Defoliation and Harvest Timing Effects on Yields, Quality, and Net Revenues

Authors: James A. Larson, C. Owen Gwathmey, and Robert M. Hayes
Pages: 13-27
Economics and Marketing

Producers need methods to determine the relationship between early defoliation and net revenues for cotton (Gossypium hirsutum L.) in a short-season environment. This study evaluated the effects of alternative defoliation timing and harvest-aid strategies on lint yields, prices adjusted for fiber quality, and net revenues. 'Stoneville 474' or 'Stoneville 4892 BR' was planted in May 1998, 1999, and 2000, and the crops were monitored using the COTMAN Expert System. Harvest-aid treatments were (i) a tank mixture of thidiazuron (N-phenyl-N’-1,2,3-thiadiazol-5-ylurea), tribufos (S,S,S-tributyl phosphorotrithioate), and ethephon [(2- chloroethyl)phosphonic acid]; and (ii) a prepared mixture of cyclanilide {1-[[(2,4-dichlorophenyl)amino]carbonyl]cyclopropanecarbo xylic acid} plus ethephon. These treatments were applied at 361, 417, 472, and 528 degree-d (base 15.6°C) after cutout each year. Price differences for fiber quality were calculated using fiber quality measured from the experiment and North Delta spot price quotations from contrasting marketing years. Net revenues were estimated using lint yields, price differences, harvest-aid materials and application expenses, and harvesting costs. Results consistently showed the harmful effects of premature crop termination and the beneficial effects of delayed termination beyond the nominal threshold of 472 degree-d. Additional yield occurred with delayed crop termination. Improved fiber quality and enhanced yields from cotton harvested after defoliation at 528 degree-d maximized cotton crop profitability. Findings suggest that delaying defoliation to 528 degree-d can facilitate a single harvest of cotton. However, the potential advantages of delayed defoliation need to be weighed against the potential risks of later harvest when inclement weather is more probable.