Igr Evaluation Experiment I, 1994

Abstract

Abstract This experiment was conducted in 3 miniblocks, each Vi acre, of 14-yr-old trees on M 7A rootstock. Trees measured 18 ft in height and 17 ft in width and were planted at a spacing of 20 × 20 ft. The experimental design consisted of a single Vi acre miniblock for each of two V71639 treatments, and half of the center Vi acre miniblock for each of a Guthion treatment and 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 of application were 6 May (petal fall [PF]), 24 May (first cover [1C]) for Guthion only, 31 May (first cover [1C]) for V71639 only, 8 Jun (second cover [2C]) for Guthion only, 14 Jun (second cover [2C]) for V71639 only, 23 Jun (third cover [3C]) for Guthion only, 7 Jul (fourth cover [4C]), 21 Jul (fifth cover [5C]), 4 Aug (sixth cover [6C]), 18 Aug (seventh cover [7C]), and 1 Sep (eighth cover [8C]). This program resulted in a total of 8 applications in the V71639 plots and 9 applications in the Guthion plot. Other materials applied separately to all treatments were Captan, Kocide, Nova, Penncozeb, Rubigan, Streptomycin, Topsin-M, and Ziram. Treatment effect was evaluated by counting insects on the periphery of four single-tree replications in the center row(s) of each treatment plot periodically during the season. Control of SA was determined by counting aphids on the most infested leaf on each of 5 terminals/tree. Effect of treatments against RLH was evaluated by counting nymphs on the underside of 25 leaves/tree. Treatment effect against STLM was determined by counting tissue-feeding mines observed during a 5 min period. Control of fruit-feeding insects was determined by scoring injury on 100 picked apples/replication on 3 Aug and on 100 picked apples/replication plus up to 100 drop apples/replication on 21 Sep.