Impact of Insecticides on Lepidopterous Larvae and Leafminers on Tomatoes, 1992

Abstract

Abstract Seedlings were transplanted in a sandy loam type soil on 30 Jun at the University of California South Coast Field Station in Santa Ana, California. Experimental plots were 4 rows wide (5 ft centers) by 40 ft long and separated by a 5 ft buffer. The tomato transplants were sprinkle irrigated for 1 week, and drip irrigated thereafter (water pH 7.2-7.5). Treatments were replicated 4 times in a randomized complete block design. Weekly applications were initiated at first fruiting. Application dates were 6, 13, 20, 27 Aug and 3, 10, 17, 24 Sep and 1 Oct. A tractor-mounted boom sprayer with 6 nozzles per row incorporated D-3 orifice disks, #25 cores, and 50 mesh screens. Operating pressure was 100 psi delivering 100 gal/acre. Spreader sticker (Leaf Act 80) was included for all treatments at 0.04%. Except for the AC 303630 without oil treatment. Leafminer populations were evaluated by weekly counts of leafminer prepupae and pupae in four 9 by 11 inch trays/ replicate from 12 Aug through 30 Sep, inclusive. On 7-9 Oct, 200 mature-green to ripe fruit were harvested from the center 2 rows of each replicate (800 per treatment) and examined for internal damage (primarily H. zea) and external damage (primarily S. exigua and K. lycopersicon).