Several methods of timing the application of harvest aid products are used in the industry. The most common methods are sixtypercentopen and four nodes above cracked boll. Two less common methods are the Cotman and Lewis methods. These wereevaluated for three years. The third year four trials were conducted using irrigated and dryland on both normal and highnitrogen conditions. The general order of application was Cotman followed by the Lewis method. Then the four nodes abovecracked boll followed the sixty-percent open method. In 1999 all methods were ready on the same day. In 2000 the highnitrogen irrigated field did not cutout until late August. The Cotman rule is that if cutout is after the date that a flower has afifty-percent chance of maturing then that date is used for starting the DD60 count. The later defoliants were applied resulted inincreased lint yields and higher micronaire values. The micronaire was 5.0 or greater four times out of six when the four nodesabove cracked boll was used. The sixty- percent method resulted in a micronaire value of 5.0 or greater one half of the time.The Cotman and Lewis methods had a micronaire value of 5.0 or greater only one time out of six. Since the Lewis method waslater than Cotman, it had the higher lint yield. The reduction in lint production by the Lewis method as compared to sixtypercentopen was more than offset by the increased value of the lint due to the elimination of micronaire marketing penalties.The Lewis method protected the micronaire and lint yield better than any of the other methods.
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