Boll openers in cotton: effectiveness and environmental influences

Abstract

The indeterminate growth of cotton ( Gossypium hirsutum L.) often results in a boll population at various stages of maturity when the crop is harvested. Boll opening compounds can be used to facilitate harvest by accelerating the opening of green bolls. Field trials were conducted at two locations in 1996 and 1997 to test the efficacy of four commercially available boll openers that stimulate ethylene production or desiccate the plant. Two of these boll openers are new to the marketplace: Finish™, ethephon+cyclanilide (2-chloroethyl phosphonic acid+1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid), and CottonQuick™, ethephon+AMADS (2-chloroethyl phosphonic acid+1-aminomethanamide dihydrogen tetraoxosulfate). Open bolls were hand harvested at 3–7 days intervals after application of the boll openers, and environmental conditions in conjunction with these harvests were recorded. The desiccant, paraquat (1,1′-dimethyl-4,4′-bipyridinium dichloride), was found to have erratic boll opening activity. Two products that contain ethephon plus the synergists cyclanilide or AMADS were found to have equal or higher rates of boll opening than ethephon alone. The rate of boll opening of all compounds was influenced more by the accumulation of heat units than by the amount of time following the application of boll openers. Although erratic, boll opening activity from paraquat application can be significant. Moreover, the reliability of ethephon based products, which are consistent boll openers, may be enhanced by formulations that contain a synergist. Heat unit accumulation may be used to predict and model the efficacy of boll opening with these harvest aides.