Insecticidal Impact on Lepidopterous Larvae and Leafminers on Celery, 1986

Abstract

Abstract Celery was transplanted in a sandy loam soil on 16 Aug at the University of California's South Coast Field Station. The plants were sprinkler irrigated for 3 wk and drip irrigated (water pH 7.2-7.5). Experimental plots were 3 beds wide (2 rows/bed on 40-inch centers) by 50 ft and separated with a 5-ft buffer with 4 replicates of each treatment in a randomized complete block design. Weekly application dates included 12, 19, and 26 Aug; 4, 10, 16, 23, and 30 Sep; and 7 and 14 Oct. All chemicals except Trigard 5 SC (through drip lines), Trigard 3G (banded on bed on 22 July only) and AC 290230 and AC 290678 (3 applications; 12 Aug, 23 Sept, and 14 Oct) were applied by a tractor-mounted boom sprayer operated at 100 psi. As plant height and foliage density increased, nozzles varied from 1 to 3 per row and carrier (H2O) increased from 30 gal/acre (12 Aug to 19 Aug) to 50 gal/acre (26 Aug) to 100 gal/acre (4 Sept on). Disk-type cone nozzles incorporated D-3 orifice discs, #23 or #25 cores, and 50 mesh screens. All treatments except Abamectin received spreader sticker (Leaf Act 80A). Antifoam (No-Foam) was used with all treatments. Leafminer populations were evaluated by weekly counts of leafminer prepupae and pupae in four 51/2- × 11-inch trays per replicate, when the plants reached a suitable height. Only the first 4 consecutive weeks' data were included in the analyses, as leafminer populations were quite low for the remainder of the season. The number of dead adult parasites of Liriomyza spp. were recorded in the same manner and on the same dates listed for pupal counts. Evaluation of Lepidoptera populations was based on no. of damaged plants found in 25 plants/replicate (100/treatment) from the center 2 rows of each replicate at harvest (23 Oct). Beet armyworm (Spodoptera exigua) and black cutworm (Agrotis ipsilon) damage were recorded separately.