Impact of sicklepod control on several insect pests and their arthropod natural enemies in Florunner peanuts

Abstract

The impact of pesticides applied for sicklepod ( Cassia obtusifolia L.) control on peanut ( Arachis hypogaea L.) insect pests and predacious arthropods in Florunner peanut fields was investigated in 1982 and 1983. Pesticides examined included post-emergence applications of toxaphene and dinoseb. Weed-free periods of 2, 6, and 14 weeks were also included to determine the effects of weediness on insect abundance. A randomized complete design with four replicates was used, than untreated plots. Corn earworm ( Heliothisi zea (Lepidoptera: Noctuidae)) populations were greater with eight-row (91 cm each) by 9 m plots. Plots treated with toxaphene yielded more peanuts (α=0·05) than untreated plots. Corn earworm ( Heliothis zea (Lepidoptera: Noctuidae)) populations were greater and threecornered alfalfa hopper ( Spissistilus festinus (Homoptera: Membracidae)) populations were lower (α=0·05) in toxaphene-treated plots on some sample days. Predator populations were depressed initially by toxaphene applications but recovered to levels higher than those in untreated populations. Some sicklepod was beneficial in increasing predacious arthropod populations in peanuts. Very weedy plots yielded significantly less peanuts than plots with good weed control, indicating the importance of proper sicklepod management.