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

Abstract

The 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.

Fitting Short Duration Cowpea into a Cotton-Based Cropping System in Tanzania: Effect of Planting Pattern, Time of Planting Cowpea, and Insecticide Application to the Cotton

“…The cotton was either left unsprayed or sprayed with cypermethrin 9% ED, using an Electrodyn sprayer (ICI), at 31.6 g ha" 1 active ingredient. Spray was applied to the sole and intercropped cotton six times at ten day intervals starting at flowering time, or approximately 56 days after planting, as recommended for the control of insect pests of cotton in eastern Tanzania (Kabissa, 1989). The use of the Electrodyn sprayer was intended to target the spray droplets accurately onto the cotton by placing the nozzle between two cotton rows and 40 cm above the plants.…”

Control of Low-Level Nantucket Pine Tip Moth Populations: A Cost-Benefit Analysis

“…Such thresholds are useful for prioritizing areas where control techniques are warranted (Saunders et al 1985, Coulson et al 1988, MacLean and Porter 2001. Although determination of the EIL has been difficult for most pests because of the great number of biological and economic parameters involved (Poston et al 1983, Onstad 1987, Skold et al 1995, many have attempted to establish damage thresholds for various pests as a first step toward integrated pest management (IPM) (Burts 1988, Stewart and Sears 1988, Kabissa 1989, Ezulike and Egwuata 1990, Theunissen and Schelling 1997).…”