Chemical Control of Cabbage Root Aphids 1987

Abstract

Abstract Cabbage was planted in Hidalgo fine sandy loam soil on 11 Nov 1986 on the Agricultural Research Farm of Rio Farms in Monte Alto, Tex. Row culture was double-row with 40-inch spacing between beds. Plants were thinned to a 12- inch spacing on 12 Dec. The experiment was arranged as a randomized complete block with 4 treatments and 4 replications. Plots consisted of 2 adjacent beds 70 ft long; 10-ft alleys separated replications, insecticides were applied in a liquid fertilizer (N-32) solution and were injected as a side-dressing on 8 Jan 1987. A commercial liquid fertilizer applicator equipped with 3 shanks per bed and calibrated to discharge 25 gal/acre delivered the treatment solutions ca. 4 inches below the soil surface. Soil temp was 20°C. Root aphid population density was estimated using a simple flotation technique. Roots from 3 randomly selected plants were washed in a CaCl solution (1 tablespoon CaCl/gal water), and insects floating to the surface were counted. Surveys were made pretreatment on 8 Jan and at 2 and 5 weeks, posttreatment on 23 Jan and 13 Feb. Two 3-plant samples were taken randomly per plot. Yields were determined by hand-harvesting both beds in a 15-ft section near the center of each plot. Only cabbage heads of commercially acceptable size were harvested during each of 3 harvests; thus, weight per head was consistant among treatments. Following the final harvest of marketable heads, all cabbage from the harvest area was cut; these yield data were combined with total marketable yield to produce total yield values. All data were analyzed by ANOVA, and means were separated by LSD.