Igr Evaluation, 1995

Abstract

Abstract This experiment was conducted in 4 miniblocks, each ⅓ acre, of 15-yr-old trees on M 7A rootstock. Trees measured 16.5 ft. in height and 16 ft. in width and were planted at a spacing of 20 X 20 ft. The experimental design consisted of half a miniblock (18 trees) for each of 6 spray treatment combinations and an entire miniblock for the untreated plot. Insecticides were applied as complete sprays to both sides of the tree with a Swanson DA500A airblast sprayer, which traveled at 2.3 mph and delivered a spray volume of 100 gpa. Dates (stage or degree-days after first trap catch of spring CM) of application were 11 Apr (tight cluster), 18 Apr (pre-pink), 12 May (petal fall), 26 May (273), 5 Jun (405), 8 Jun (462), 13 Jun (548), 22 Jun (696), 6 Jul (987), 18 Jul (1249), 1 Aug (1601), 16 Aug (1942), and 1 Sep (2225). Other materials applied separately to all treatments were Dithane, Kocide, K-salt (NAA), Nova, Penncozeb, Rubigan, Topsin-M, and Ziram. Treatment effect was evaluated by counting insects and injury on the periphery of 4 single-tree replications in the center row(s) of each plot periodically during the season. Control of SA was evaluated by counting aphids on the most infested leaf on each of 10 terminals/tree. WALH and RLH control was evaluated by counting nymphs on the underside of 25 leaves/tree. Control of CM and OFM was determined by counting injured apples during a 5 min period/tree. Treatment effect against STLM was determined by counting tissue-feeding mines observed during a 5 min period/tree. Control of fruit-feeding insects was determined at harvest by scoring for injury 100 picked apples/replication plus up to 100 drop apples/replication on 19 Sep.