LATE-SEASON TERMINATION EFFECTS ON COTTON FRUITING, YIELD, AND BELL WEEVIL (COLEOPTERA, CURCULIONIDAE) DAMAGE IN TEXAS DRYLAND COTTON

The plant growth regulator ethephon, Prep ([e-chloroethyl] phosphonic acid), and the desiccant arsenic acid, Desiccant L-10, were evaluated for their effects on late-season squares, green bells, and yield of th e cotton, Gossypium hirsutum, cultivars, 'Lankart 511','Lankart Sel. 6 11', and 'TAMCOT CAB-CS', in a dryland cotton production system in 199 0 and 1991. Damage to squares and boils by the bell 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 co mpared with untreated cotton. Plots were harvested in early December a fter a killing freeze. Both Prep and Desiccant L-10 reduced the number of green bells and cotton squares damaged by boil weevils in all cult ivars in October. Yield was not significantly reduced by either chemic al in 1990 or in 1991. The late-maturing 'Lankart Sel. 611' had lower yields across treatments in 1990 and in 1991 than the intermediate-mat uring 'Lankart 511' and the early-maturing 'TAMCOT CAB-CS'. A single l ate-season application of a harvest aid chemical for reduction of fall food may help control bell weevils and reduce the need for fall insec ticide applications in dryland cotton. Relevance of this research to t he Texas Bell Weevil Eradication Program is discussed.