Pretreatment Approach to Defoliation of Acala Cotton

Steve Wright¹ , Robert Hutmacher² , Gerardo Banuelos^3, Tulio Macedo⁴ , Daniel S. Munk⁴, Mark P. Keeley⁵ , John Robles⁶ , (1) University of California, Tulare, CA, (2) University of California, Shafter, CA, (2)USDA-ARS, Shafter, CA, (3) University of California Cooperative Extension, Tulare, CA (4) Univ. of California, Madera, CA, (5)Univ. of California, Shafter, CA, (6)University of California, Fresno, CA,

Harvest Aid studies were conducted at the Westside Research and Extension Center in Five Points California to evaluate the evaluate the effect of early applications of Ginstar  or Ginstar plus Finish.  In 2007 Ginstar treatments at 3-6 oz rate applied at the 6 nodes above cracked boll followed by a secondary treatment of 6-8 oz of Ginstar or Sodium Chlorate gave 20 percent higher defoliation, 30 percent higher desiccation, and 15 percent improved open boll compared to similar treatments with a two shot approach applied at the standard 4 NACB stage. The 4 NACB treatments did not improve open boll even after 32 DAT.  Yield data showed a yield reduction with an early application of Finish and a slight loss with an early application of Ginstar in 2007 but not in 2006. Micronaire was slightly reduced with the 6 NACB timing but not in a negative way.

 

The 2008 studies have not been completed but will be presented. A field of Phytogen 725 has been managed at the WSR&ES for this study.  A follow up on a 2 step approach done in 2006 and 2007 which showed improved defoliation and boll opening by starting with a 4 oz. rate of Ginstar at 6 NACB followed by higher rates of harvest aids along with ethephon at 4 NACB to bring about an earlier harvest. Preliminary data indicated that this approach worked well but there are still questions remaining on possible yield loss. Early applications of Shark will be evaluated also for defoliation and earlier termination.