Insecticide Evaluation, 1991

This experiment was conducted in a 5.4 acre block of 37-yr-old trees, which measured 16.5 ft in height and 23 ft in width and were planted at a spacing of 20 × 40 ft. The experimental design consisted of 6 single-tree plots (3 'Rome Beauty,' 3 'Golden Delicious') in a randomized block design. Insecticides were applied with a Swanson DA500A airblast sprayer, which traveled at 2.4 mph and delivered a spray volume of 100 gal/acre. Dates of application were 2 Apr (delayed dormant [DD]), 9 Apr (prepink [PP]), 8 May (petal fall [PF]), 21 May (first cover [1C]), 31 May (second cover [2C]), 13 Jun (third cover [3C]), 27 Jun (fourth cover [4C]), 16 Jul (fifth cover [5C]), 30 Jul (sixth cover [6C]), 12 Aug (seventh cover [7C]), and 29 Aug (eighth cover [8C]). Other materials applied separately to all treatments were Agristrep, Bordeaux mixture, Captan, Dodine, NAA, Nova, Rubigan, Solubor, and Topsin-M. Control of RAA was evaluated by counting colonies/tree. Effect of treatments against SA was determined by counting aphids on the most infested leaf on each of five terminals/tree around the periphery of'Rome Beauty.' Control of WALH and RLH was evaluated by counting nymphs on 25 leaves selected from the periphery of trees. Treatment effect against STLM was determined by counting mines observed in 5 minutes around the periphery of trees. Control of fruit-feeding insects was determined by scoring for injury 600 picked apples/treatment (100/replication) plus up to 600 drop apples/ treatment (up to 100/replication) sampled on 17 Sep. Fruit picked from 'Golden Delicious' trees were rated for finish as 0 (no russet), 1 (enlarged and raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>50% russeted surface).