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Evaluation of Harvest-Aid Chemicals for Early Fall Termination of Cotton as a Boll Weevil Management Strategy

L.E. Clark, J.E. Slosser, E.P. Boring, T.W. Fuchs, R.R. Minzenmayer


The boll weevil is the primary insect pest of cotton (Gossypium hirsutum L.) in the Texas Rolling Plains. Control of this insect is key to successful cotton production. Uniform planting of cotton during the last half of May is a basic part of recommended boll weevil management practices in the area. When uniform planting is used, boll weevil control with insecticides during the growing season is seldom economical at yield levels <1 bale/acre. Dryland cotton is grown on 90-95% of the acreage, and the average yield level is about 300 lb/acre (12). Alternative methods are needed to control the boll weevil. Effective harvest-aid chemicals used to terminate the crop before early October can reduce the number of boll weevils entering diapause and thus reduce winter survival. This should reduce or eliminate the need for in-season insecticide applications. Ginstar®; was used effectively in tests in Hardeman and Wilbarger counties on cotton in the 1994 growing season. Yield and lint grades were not adversely affected when Ginstar was applied in mid- and late September in dryland and in late September in irrigated cotton. In the dryland test in Hardeman County color grade was better in the defoliated cotton than in the freeze terminated cotton that was not harvested until eight to nine weeks after the chemically terminated cotton. Regrowth of the freeze terminated cotton produced 18-20 thousand squares and small bolls/acre and 12-13 thousand bolls/acre with weevil feeding punctures between late September and 16 November when the killing freeze occurred. Ginstar, applied 27 September at 8 and 12 oz/acre rates, was an effective defoliant and did not adversely affect lint grades in dryland 'HS-26' cotton that yielded about 1.3 bales/acre in Wilbarger County. The 12-oz/acre rate of Ginstar was a more effective defoliant than a tank-mix of Prep®; and Def®; applied 27 September to irrigated 'Stoneville 132' at a rate of 1 pt each per acre. Lint grades were not different for the two defoliants. Ginstar applied to irrigated Deltapine 5409 in late September in Tom Green County resulted in lower micronaire values and yield than the untreated check.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 977 - 982
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998