Insect Control on Cabbage, 1985

Abstract

Abstract ‘Greenback’ cabbage seedlings were transplanted on 7 Mar at the University of California’s South Coast Field Station in Santa Ana, California. Experimental plots were 4 rows wide (40 inch centers) by 36 ft long separated by a 3-ft buffer. The cabbage transplants were sprinkler irrigated for 2 wk, and drip irrigated thereafter (water pH 7.2-7.5). Treatments were replicated 4 times in a randomized complete block design. Alternate week applications were initiated when transplants were 2 wk of age. Application dates included 21 Mar, 4 and 18, Apr and 2 and 16 May. A tractor-mounted boom sprayer was operated at 100 psi. As plant height and foliage density increased, nozzles varied from 1-6 per row and carrier (water) increased from 50 gal/acre (21 Mar-4 Apr) to 100 gal/acre (18 Apr on). Disk type cone nozzles incorporated D 1-3 disks, #23 or 25 cores and 50 mesh screens. All treatments included 0.04% spreader-sticker (Leaf Act 80A). Evaluation of Lepidoptera populations was based on no. of larvae/plant found on 10 plants/replicate (40 per treatment) from the center 2 rows of each replicate every week. The diamondback moth, and cabbage looper, were recorded separately. Aphid counts were indexed as follows: 1 = 0-10, 2 = 11-25, 3= 26-50, 4 = 51 +. Because of high initial densities, and the rapid movement of alate aphids between plots, index values approaching one can be considered good.