Insecticide Evaluation II, 1997

Abstract

Abstract This experiment was conducted in a 0.8 acre block of 17-yr-old trees on MM106 rootstock. Trees measured 13.5 ft in height and 14.5 ft in width and were planted at a spacing of 18 X 24 ft. The experimental design consisted of a single plot of 3 rows X 8 trees/row for each of two spray treatments which were separated by a single untreated plot of 4 rows X 8 trees/row. Insecticides were applied as complete sprays to both sides of the trees with a Swanson DA500A airblast sprayer, which traveled at 2.4 mph and delivered a spray volume of 100 gpa in treatment 1 and 250 gpa in treatment 2. Dates of application were 2 May [petal fall (PF)], 14 May [first cover (1C)], 29 May [second cover (2C)], 12 Jun [third cover (3C)], 24 Jun [fourth cover (4C)], 8 Jul [fifth cover (5C)], 22 Jul [sixth cover (6C)], 5 Aug [seventh cover (7C)], 19 Aug [eighth cover (8C)], and 2 Sep [ninth cover (9C)]. Other materials applied separately to all treatments prebloom were COCS, Dithane, and Nova. Other materials applied postbloom at various times in tank mix with treatment 1 were Nova, Dithane, Topsin-M, and Ziram. Treatment effect was determined by counting arthropod pests or injury on 4 single-tree replications of ‘Delicious’ for European red mite, and ‘Golden Delicious’ for all other pests, in each plot periodically during the season. RAA control was evaluated by counting colonies per tree. Control of SA was determined by counting aphids on the most infested leaf on each of 5 terminals per tree. Treatment effect against WALH and RLH was determined by counting nymphs on the underside of 25 leaves per tree. PLH control was determined by counting adults and nymphs on the 5 youngest leaves on each of 10 terminals per tree. Effect of treatments against ERM was deter-mined by sampling 25 leaves/tree, removing mites with a mite-brushing machine, and counting motile stages with a binocular microscope. STLM control was evaluated by counting all tissue-feeder mines during a 5 minute period per tree. Control of fruit-feeding insects was determined by scoring for injury 100 picked apples and up to 100 drop apples per replication of ‘Golden Delicious’ on 17 Sep. ‘Golden Delicious’ fruit were also rated for russeting as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>50% russeted surface).