Insecticide Evaluation, 1996

This experiment was conducted in 3 miniblocks, each 1/3 acre, of 18-yr-old trees on MM 111 rootstock. Trees measured 15 ft. in height and 14 ft. in width and were planted at a spacing of 20 x 20 ft. The experimental design consisted of 6 single-tree replications per treatment, with 2 replications per mini-block in a randomized block design. Each replicate was surrounded by 1 unsprayed tree on each side. 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 of application were 25 Apr [pink (P)], 13 May [petal fall (PF)], 30 May [first cover (1C)], 13 Jun [second cover (2C)], 26 Jun [third cover (3C)], 11 Jul [fourth cover (4C)], 25 Jul [fifth cover (5C)], 7 Aug [sixth cover (6C)], 21 Aug [seventh cover (7C)], and 5 Sep [eighth cover (8C)]. Other materials applied separately to all treatments were Agri-Mycin, COCS, Dithane, Nova, Penncozeb, Rubigan, and Ziram. Treatment effect was determined by counting insects on the periphery of test trees periodically during the season. RAA control was determined by counting colonies per tree. Control of SA was evaluated by counting aphids on the most infested leaf on each of 10 terminals per tree. Effect of treatments against ERM was determined by sampling 20 leaves/tree (5 replications), removing mites with a mite-brushing machine, and counting motile stages with a binocular microscope. Control of STLM was determined by counting all tissue-feeding mines during a 5 minute period per tree.