IGR Evaluation Experiment II, 1994

Abstract

Abstract This experiment was conducted in a 2.5 acre block of 11-yr-old trees on M.7A rootstock. The trees measured 14.5 ft in height and 12.5 f in width and were planted at a spacing of 20 × 20 ft. The experimental design consisted of four replications (two ‘Delicious’, two ‘Criterion’) of nine-tree plots (three rows × three trees/row) in a randomized block design. 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. Applications were timed using degree-days (DD) to coincide with the beginning of egg hatch of each generation of CM and TABM. Dates of application were 23 May (211 DD50 after first codling moth catch), 8 Jun (512 DD45 after first tufted apple bud moth catch), 21 Jul (1535 DD5U after first codling moth catch in the spring), and 4 Aug (2224 DD45 after first tufted apple bud moth catch in the spring). Other materials applied separately to all treatments were Captan, Kocide, Nova, Penncozeb, Rubigan, Streptomycin, Topsin-M, and Ziram. Treatments were evaluated by taking insect counts from the periphery of the center tree in each plot. Effect of treatments against RLH and WALH was determined by counting nymphs on the underside of 25 leaves per tree. Control of STLM was evaluated by counting tissue-feeding mines observed on each tree during a 5 min period. Control of fruit-feeding insects was determined by scoring 100 picked apples/replication plus up to 100 drop apples per replication for injury on 23 Sep.