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A Practical Plant-Based Economic Injury Level for Early-season Cotton Insect Management

Sha Mi, Diana M. Danforth, Mark J. Cochran and N. Philip Tugwell


Early-season cotton insect management faces the challenge to balance the advantages of earliness with the desire to rely more on cotton's compensatory capability and to maintain natural enemies. Balancing management options is further complicated by such factors as costs of damage, induced delays, aggregate effect of multiple pest species at sub-threshold densities, price of insecticides and crop value. Conventional economic injury level (EIL) fails to capture the insect population dynamics and the compensatory nature of cotton. Farmers who use economic threshold (ET) to initiate insect control decisions find it hard and impractical to relate ET with EIL. In this paper, a plant-based EIL is developed to calculate a break-even injury level (square shed frequency) up to first flower to validate an ET. It incorporates control costs, crop value, dynamic plant-monitoring results and cotton's compensation capacity into the calculation. Producers can compare the actual shed rate at any time prior to first flower with the calculated EIL to determine the effectiveness of an ET, and whether an adjustment on current insect control tactics is needed. The EIL model has been incorporated into the COTMAN computer program to facilitate implementation by users.

Reprinted from Proceedings of the 1998 Beltwide Cotton Conferences pp. 361 - 366
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998