Apple, Airblast Insect Experiment, 1990

Experimental sprays were applied to 2 tree plots in a randomized block design consisting of 2 replicates of 'Yorking', 2 replicates of 'Golden Delicious', and 1 replicate of 'Stayman'. Trees were planted to a spacing of 20 × 30 ft and were 15 yr old. Experimental sprays were applied with a Friend Airmaster '309' at 25 gal/acre per alternate side spray (50 gal/acre both sides) driven at 2.3 mph. Rates for treatments are listed as amounts/acre/both sides spray. A routine schedule of fungicides (Nova 40 WP and Dithane M-45) was maintained throughout the experiment. Effectiveness of treatments on the aphid complex was evaluated by counting aphid-infested leaves/10 terminals and aphids on the most infested leaf/terminal. The effect of treatments on WALH was evaluated by counting nymphs/25 injured leaves/tree. STLM was sampled by a 5-min count of mines around the periphery of test trees. Effectiveness of treatments on ERM and Z. mali was evaluated by counting mites several times during the season on samples of 25 leaves/tree, 125 leaves/treatment. The effect of treatments on S. punctum was evaluated by 3-min counts of adults and larvae around the periphery of test trees. Effectiveness of treatments on fruit feeders was assessed by scoring for injury all drops after 1 Jul and 2 picked samples on 16 Aug and 20 Sep. Pest pressure was moderate throughout the season. Russet ratings are based on 30 Golden Delicious apples/replicate, 60/treatment. Fruits were rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>51% russeted surface). Possible ranges are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface), 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to >51% russeted surface).