Igr Evaluation Experiment 1,1996

Abstract

Abstract This experiment was conducted in 4 miniblocks, each 1/3 acre, of 16-yr-old trees on M 7A rootstock. Trees measured 16.5 ft. in height and 16 ft. in width and were planted at a spacing of 20 X 20 ft. The experimental design consisted of half a miniblock (18 trees) for each spray treatment and an entire miniblock for the untreated plot. Insecticides were applied as complete sprays to both sides of the trees with a Swanson DA500A airblast sprayer, which traveled at 2.3 mph and delivered a spray volume of 100 gpa. Dates (plant growth stage and degree-days after first pheromone trap catch in spring of codling moth, TABM, OFM of application were 12 Apr (delayed dormant), 18 Apr (pre-pink), 10 May (petal fall, 163,-,296), 20 May (266, 115,442), 3 Jun (410, 317, 644), 11 Jun (561, 508, 835), 18 Jun (721, 703, 1031), 3 Jul (1034, 1091, 1418), 11 Jul (1191, 1285, 1613), 25 Jul (1499, 1641, 1969), 2 Aug (1626, 1831, 2158), and 8 Aug (1754, 1989, 2317). Other materials applied separately to all treatments were Agri-Mycin, COCS, Dithane, Nova, Penncozeb, Rubigan, and Ziram. Treatment effect was evaluated by counting insects and injury on the periphery of 4 single-tree replications in the center row(s) of each plot periodically during the season. RAA control was determined by counting colonies per tree. Con-trol of WALH was determined by counting nymphs on the underside of 25 leaves per tree. Effect of treatments against ERM was determined by sampling 25 leaves/tree, removing mites with a mite-brushing machine, and counting motile stages with a binocular microscope. OFM control was determined by counting injured terminals per tree. Control of STLM was determined by counting all tissue-feeding mines during a 5 minute period per tree. Effect of treatments against TABM was determined by counting leaf shelters and live larvae within leaf shelters per tree.