Apple, Spring Control of the Oblr with Bacillus Thuringiensis (Bt) Products, 1992

Three different Bt products were evaluated for their ability to control overwintered OBLR larvae. The test was conducted in two commercial orchards located near Milton-Freewater, OR. Trees in the HOME orchard were 20-year-old spur type ‘Red Delicious’ on dwarfing roots. Trees in the GALA orchard were 3-year-old ‘Gala’ on dwarfing roots. In the HOME orchard the test design consisted of two-tree plots replicated five times in randomized complete blocks. In the GALA orchard the test design consisted of five-tree plots replicated five times in randomized complete blocks. Treatments were applied with a handgun sprayer at 300 psi to the point of drip, simulating a dilute spray of approximately 400 gal/acre. First application of all treatments was made on 18 Mar, at the half-inch green-tip (HIG) stage of fruit bud development. The second application of the Bt products only was made on 25 Mar at the pink (P) stage of fruit bud development. On 8 Apr each tree was examined and the number of active feeding sites (live leafroller larvae) recorded.