Apple, Control of the Pandemis Leafroller with Bacillus Thuringiensis and Conventional Products in Spring, 1993

Different B. thuringiensis products were compared with conventional insecticides for their ability to control PLR larvae of the overwintering generation. The test was conducted in an apple orchard near Wenatchee. Trees were 4-yr-old spur type ‘Oregon Spur II’ on dwarfing rootstock (M.7). Treatments were applied to three-tree plots replicated five times using a RCB design. All treatments were applied with a handgun sprayer at 300 psi to the point of drip, simulating a dilute spray of approximately 400 gpa. Pre-treatment counts were made on 19 Apr by examining 20 fruit buds per tree and recording the number infested with PLR larvae. The post-treatment evaluation was made on 17 May. Each tree was examined and the total number of live leafroller larvae recorded.