How to Succeed by Doing Nothing

Abstract

Clarifying the amount of pest damage that can be tolerated without justifying insecticidal control will be useful in reducing insecticide use and in development of integrated pest management (IPM) systems. This study investigated the ability of irrigated, high‐yielding cotton (Gossypium hirsutum L.) to recover from artificially applied damage simulating that of early season insect pests. Six experiments were done across five cotton‐growing seasons. Damage included defoliation, terminal damage, and flower bud removal in a range of timings, combinations, and intensities. Crop yield was unaffected by defoliation applied before first flower buds appeared, even when 100% of true leaves were removed on three occasions (Nodes 2, 4, and 6). Crop maturity was affected by sustained high levels of leaf loss with a peak delay of 10 d after 100% defoliation three times. Up to three light tip damage events or one heavy damage event had no effect on yield and only a slight effect on crop maturity (<5‐d delay to harvest). Heavy early fruit loss (100% fruit removal from the first four fruiting branches) did not affect yield but caused a delay in maturity of ≈7 d. Equations describing the relationship between damage type, intensity, and repetition and the yield and maturity of cotton were developed and used in sensitivity analysis to define tentative damage thresholds for IPM systems in cotton.