Early Season Raa Control, 1988

The experimental design was a randomized complete block, with 6 insecticide treatments and a control replicated 5 times. Plots consisted of 4 trees, one each of the cultivars ‘Yorking,’ ‘Delicious,’ ‘Golden Delicious,’ and Rome Beauty. Experimental sprays were applied with a Myers Mity Mist airblast sprayer calibrated to deliver 50 gal/acre. Spray dates corresponded to the following phenological stages (‘Golden Delicious’): half-inch green, 6 Apr; pink, 25 Apr. A regular fungicide schedule (Benlate, Bayleton, Dithane M-45, Manzate 200) was maintained throughout the season. Postbloom insecticides (Guthion, Lannate) were applied at 1- to 2-wk intervals beginning in mid-June. Effectiveness of the sprays against RAA aphid was evaluated by counting the number of RAA-injured leaves/tree and the total number of damaged apples/tree (‘Rome Beauty’ and ‘Yorking’).