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LOGO: Journal of Cotton Science


Analysis of Returns above Variable Costs for Management of Verticillium Wilt in Cotton

Authors: T. A. Wheeler, J. P. Bordovsky, J. W. Keeling, J. G. Smith, and J. E. Woodward
Pages: 56-66
Economics and Marketing

A large-plot study located in Halfway, TX, was conducted from 2007 to 2013 in an irrigated field infested with Verticillium wilt. Management options (crop rotation, irrigation amount, variety selection) and combinations of options that can reduce this disease were compared using returns above variable costs (RVC) analysis. A continuous cotton system was compared with a crop rotation system (2-yr cotton and 1-yr sorghum). Irrigation rates consisted of a base (1.0B), base + 50% (1.5B), and base - 50% (0.5B) rates. From 2007 to 2009, 1.0B targeted 80% of the evapotranspiration (ET) needs of cotton, and from 2010 to 2013, 1.0B targeted 60% ET. Varieties planted were tolerant or susceptible to Verticillium wilt. Data collected included wilt incidence, cotton lint yield, loan value for lint, sorghum yield, fertilizer types and amounts, and total irrigation applied. Cotton prices were approximately $1.15 and $1.54/kg lint ($0.52 to $0.70/lb) (adjusted up or down by actual loan value of cotton fiber), and sorghum was valued at $0.185/ kg ($8.40/cwt). Crop rotation generally resulted in higher RVC than continuous cotton, although higher cotton prices, and ET = 60% (drier conditions) could result in both systems having similar RVC. The 1.5B rate had higher RVC, but as irrigation increased above 80% of cotton needs, RVC was reduced compared with 1.0B. The 0.5B rate resulted in lower RVC than the 1.0B rate, except when ET = 80% and a susceptible variety was grown. The 1.5B rate combined with a tolerant variety always had higher RVC than growing a susceptible variety. The combinations of 1.5B rate and growing continuous cotton resulted in the most Verticillium wilt. Conditions that aggravated Verticillium wilt resulted in lower RVC.