Cabbage Root Aphid Control 1986

Abstract

Abstract 'Sanibel' variety cabbage was planted 7 Oct into double-row beds with 40-inch centers at the Hoblitzelle Research and Demonstration Farm, Mercedes, Tex. Soil type was an Hidalgo sandy clay loam. Plants were thinned to a 6-inch spacing on 1 Nov, and 60 lb N-32 fertilizer was side-dressed on 3 Dec. Two separate experiments were conducted, one to evaluate efficacy of foliar-applied insecticides, and one to evaluate side-dressed insecticides for control of poplar petiole gall aphids (cabbage root aphids). Experimental design for both tests was a randomized complete block with 4 replications. The plots measured 2 beds by 30 ft (foliar test) or 4 beds by 30 ft (side-dress test) with a buffer row between plots. Side-dress treatments were applied on 3 Dec, and foliar sprays were begun 24 Dec. The RH-7988-treated plot received 1 foliar application, the other 2 insecticides were sprayed twice at a 7-day interval. Soil injections were applied with a liquid fertilizer applicator, and foliar sprays were discharged through a COzpowered, backpack sprayer calibrated to spray 10 gal/acre (30 psi, 4 flat-fan nozzles per plot). Efficacy was evaluated by removing the roots of 4 plants from each plot and washing them in 1 gal of water containing 1 tablespoon of CaCl. Dislodged aphids were counted as they floated to the surface of the water. Cabbage heads were harvested on 13 ft, 2 inches of row per plot to determine yield. Data were analyzed for treatment differences with ANOVA, and means were separated with Duncan's New Multiple Range Test.