Evaluation of damage thresholds for insecticidal control of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on cotton in eastern Tanzania

Abstract

AbstractThe value of damage thresholds in determining the need for insecticide sprays against Helicoverpa armigera (Hübner) on cotton was evaluated in 1984 and 1985 in eastern Tanzania. Spraying at thresholds of 10, 20, 40 and 80% damaged squares was compared against spraying on a recommended prophylactic regime of six fixed-interval sprays. In both years, spraying on damage thresholds reduced the number of insecticide applications from six to between one and five without significantly affecting control of H. armigera, seed cotton yield or overall levels of damage to cotton.