Apple, Effects of Various BT Products on Leafroller Management, 1994

Abstract

Abstract Experimental sprays were applied to single-tree plots in a completely randomized design consisting of 3 replicates of ‘Delicious’ and 3 replicates of ‘Stayman’. Treated plots were separated by others not sprayed with insecticides. The trees were 16 years old and planted at a spacing of 12 × 35 ft. Sprays were applied with a handgun from a John Bean sprayer, 35 gpm pump. Approximately 3.5 gallons of spray were applied per replicate tree (ca 360 gpa). The dates of application for the treatments were 13 and 21 Jun (1st brood control) and 8, 19 and 31 Aug (2nd brood control). All plots received a regular fungicide maintenance schedule of Benlate 50DF, Dithane 75DF, Nova 40WP and Ziram 76WP. Effectiveness on SA was evaluated by counting the number of aphid-infested leaves/10 side terminals, and the number of aphids/most infested leaf where a rating scale (0-3) was used (see table footnotes for scale). The number of aphid natural enemies was determined by counting the number observed on 10 terminals per tree. Effectiveness of the test chemicals on the ERM and ZM was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 150 leaves/treatment. Shelters of the various leafrollers were counted in a 5 min examination of each plot tree. All larvae were collected and returned to the laboratory for identification. STLM was evaluated by a 5-min count of mines around the periphery of the trees. A harvest fruit rating was made on 23 Sept.