Late-Season Termination Effects on Cotton Fruiting, Yield, and Boll Weevil (Coleoptera: Curculionidae) Damage in Texas Dryland Cotton

Abstract

The plant growth regulator ethephon, Prep ([2-chloroethyl] phosphonic acid), and the desiccant arsenic acid, Desiccant L-10, were evaluated for their effects on late-season squares, green bolls, and yield of the cotton, Gossypium hirsutum, cultivars, ‘Lankart 511’, ‘Lankart Sel. 611’, and ‘TAMCOT CAB-CS’, in a dryland cotton production system in 1990 and 1991. Damage to squares and bolls by the boll weevil, Anthonomus grandis grandis Boheman, was evaluated in 1991. All cotton cultivars treated with Prep (1.26 kg(AI)/ha) and Desiccant L-10 (2.63 1(AI)/ha) in September had reduced numbers of squares in October and November compared with untreated cotton. Plots were harvested in early December after a killing freeze. Both Prep and Desiccant L-10 reduced the number of green bolls and cotton squares damaged by boll weevils in all cultivars in October. Yield was not significantly reduced by either chemical in 1990 or in 1991. The late-maturing ‘Lankart Sel. 611’ had lower yields across treatments in 1990 and in 1991 than the intermediate-maturing ‘Lankart 511’ and the early-maturing ‘TAMCOT CAB-CS’. A single late-season application of a harvest aid chemical for reduction of fall food may help control boll weevils and reduce the need for fall insecticide applications in dryland cotton. Relevance of this research to the Texas Boll Weevil Eradication Program is discussed.