2006 Evaluation of Commercial Harvest Aid Materials in Arizona Cotton Production Systems

Abstract

A defoliation experiment was conducted during the 2006 growing season in an effort to evaluate the effectiveness of Ginstar® and FreeFall® defoliant alone and in combination with CottonQuik®. This study was conducted at the University of Arizona Safford Agricultural Center on Upland (cultivar DP655BR). Plots were planted on 20 April. Treatments were arranged in a randomized complete block design with four replications and treatments included Ginstar® at 6 and 8 oz./acre rates and Ginstar® at the 6 and 8 oz./acre rates in combination with various rates of CottonQuik® (1.5, 2, 3, and 4 pts/acre). We also evaluated a new product from DuPont, FreeFall® SC at different rates (3.2, 4.8, 6.4 oz./acre) in combination with CottonQuik® (2 pts./acre). The standard defoliation protocol among growers in southeastern Arizona is sodium chlorate plus Gramoxone®, so this treatment combination was also included. A control, not receiving any harvest prep material was also included for a total of fifteen treatments. Treatments were imposed on 13 October and evaluations were made on 20 October and 1 November. Estimations on percent leaf drop, regrowth control, and open boll were made. Lint yield was estimated by harvesting the center two rows of each plot and sub-samples were collected for fiber quality analysis. Plots were harvested on 2 November directly after the second evaluation date in an attempt to evaluate the boll opening effectiveness of the CottonQuik® material. Results indicated higher effectiveness of leaf drop or defoliation in the plots that included CottonQuik® as opposed to Ginstar® alone. The treatments performed much better that the standard sodium chlorate treatment. Percent leaf drop also increased at the higher rates of FreeFall® (4.8, 6.4 oz./acre). The percentage of open boll was also improved with the addition of CottonQuik® to the all of the treatments. However, very little significant differences were observed in lint yield and fiber quality. A trend of increased yield with the addition of CottonQuik® was observed when compared to Ginstar® alone or the standard sodium chlorate treatment. All aspects of harvest preparation including percent defoliation and boll opening appear to be significantly enhanced with the use of CottonQuik® when compared to standard Ginstar® rates alone.