Control of Diamondback Moth (Dbm) with Emamectin and Bacillus Thuringiensis Endotoxins, 1996

Abstract

Abstract Six beds 32 inches wide and 240 ft long were fumigated with methyl bromide/chloropicrin 67/33 at a rate of .220 lbs/acre, fertilized with a bottom mix of 800 lbs/acre 5-16-8 and a top mix of 500 lbs/acre of 19-0-19, and covered with black polyethylene film. The center bed of each of 2 sets of 3 beds on 6-ft centers separated by a 15 ft drive middle was planted on 5 Dec 1995 with collard seedlings var ‘Georgia’ to provide target pest inoculum. Cabbage seedlings were transplanted 29 Jan into single rows on the remaining 4 beds at 18 inch spacing. Beds were subsurface irrigated with a semi-closed system and plants sprayed with Bravo 720 at 1.5 pt/acre for disease control. Each bed of cabbage was considered a block and divided into 7 plots 34 ft long in a RCB design with 4 replications and 7 treatments. A precount on 1 April of 20 plants per replication yielded an average 1 DBM larva and 0.8 DMB pupa per plant. Treatments were applied on 2, 11, and 17 Apr at a rate of 65 gpa using a high clearance sprayer equipped with 5 yellow hollow cone Albuz ceramic nozzles per row and operating at 200 psi of pressure. A nonionic surfactant, ASPA 80, was tank mixed at the rate of 16 oz/100 gal of spray which was made up with water at pH 7.2. Proclaim was not applied on 11 Apr at the request of the company representative. Ten randomly selected plants per plot were evaluated weekly 4 to 7 DAT. Five wrapper leaves and 3 inner (head) leaves per plant were inspected for larvae classified in 3 size categories. A damage rating was determined for each plant where 1 = no apparent damage, 2 = 0-1 % surface area damage to wrappers, 3 = 2-5% damage to wrappers but none to head, 4 = 6-10% damage to wrappers, 0-5% damage to head, 5 = 11-30% damage to wrappers, 5-15 damage to head 6 = >30% damage to wrappers, 15% damage to head. Evaluations were recorded on Pesticide Research Manager version 4.06. The 15 largest heads in each plot were selected and graded for marketability on 25 Apr based on 2 levels of stringency: “Fancy” with no insect damage on the wrapper leaves or head, and “Standard” with less than 10% insect damage on wrapper leaves and less than 5% on the head, limited to the 2 outer leaves.