Agri-Mek/Adjuvant Evaluation, 1997

This experiment was conducted in a 2.1-acre block of 12-yr-old trees on M7A rootstock. The trees measured 11.5 ft in height and 10 ft in width and were planted at a spacing of 12 X 18 ft. The experiment involved 4 replications of 16- to 20-tree plots (3 rows X 4 or 5 trees/row) in a RCB design. Treatments were applied on 14 May (12 days after petal fall) 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 gal/acre. Other materials applied separately to all treatments were COCS, Confirm, Dithane, Guthion, Nova, Penncap-M, Penncozeb, Topsin-M, and Ziram. Treatments were evaluated by taking arthropod pest counts from the center ‘Delicious’ tree in each plot periodically during the season. White apple leafhopper control was determined by counting nymphs on the underside of 25 leaves per tree. Treatment effect against spotted tentiform leafminer was determined by counting tissue-feeder mines observed during a 5 minute period per tree. Control of European red mite was evaluated by sampling 25 leaves per tree, removing mites with a mitebrushing machine, and counting motile stages with a binocular microscope. ‘Golden Delicious’ fruit were 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) on 16 Sep.