Insecticide Evaluation, 1997

Abstract

Abstract This experiment was conducted in a two-acre orchard of 19-yr-old trees on Halford rootstock. Trees measured 11 ft in height and 13.5 ft in width and were planted at a spacing of 20 X 20 ft. The experimental design consisted of a single plot of 18 trees (6 rows X 3 trees/row) for each of 8 spray treatments and a single plot of 36 trees (6 rows X 6 trees/row) for each of 8 spray treatments and a single plot of 36 trees (6 rows X 6 trees/row) as an untreated check. Insecticides were applied as complete sprays to both sides of the trees with a Swanson DA500A airblast sprayer, which traveled at 2.4 mph and delivered a spray volume of 100 gpa in treatments 1-7 and 250 gpa in treatment 8. Dates [stages or OFM degree days from first moth catch] of application, which differed among treatments, were 21 Apr [petal fall], 29 Apr [late petal fall], 5 May [shuck split], 19 May [shuck fall], 4 Jun [586], 16 June [830], 19 Jun [920], 24 Jun [1085], 30 Jun [1253], 3 Jul [1354], 15 Jul [1692], 29 Jul [2119], and 7 Aug (2318]. Other materials applied separately to all treatments, except for no. 8, were Bravo 720, Orbit, Topsin-M and Ziram. Treatments were evaluated by taking insect counts or assessing injury on 4 single-tree replications from the center of each plot. GPA control was evaluated by counting the number of colonies per tree. Control of first-generation OFM was determined by counting injured terminals per tree. Fruit injury from OFM and catfacing insects was determined by sampling 100 picked fruit from each tree replicate on 19 Aug.