Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/1998
Publication Date: N/A
Technical Abstract: Cotton (Gossypium hirsutum L.) desiccants and defoliants are not consistently efficacious. We are systematically determining bases for inconsistency of several compounds. Low absorption of compound into the leaf could limit efficacy. Export from the blade could enhance or decrease defoliation depending if the compound is imported by leaves or other organs, respectively. The effects of adjuvants upon absorption and export of radiolabeled compound applied to individual leaves was examined. Ammonium sulfate as a supplement increased uptake of fluthiacet-methyl and endothall, but decreased paraquat uptake. Pelargonic acid increased uptake and efficacy of unformulated paraquat, but increased efficacy, not uptake of endothall. The greater export of compounds from very young leaves and upon late-day application suggested faster export from or slower activation in leaves might enhance efficacy. If consistency of efficacy can be enhanced, then the temptation to apply these herbicides in excess will be lessened, and the environmental quality preserved.