Western Spruce Budworm Control with Three Dosages of Reldan, 1977

Reldan (Chlorpyrifos-methyl) was applied at the rate of 8 oz ai gal/acre, 4 oz ai gal/acre, and 2 oz ai gal/acre against 4 th and 5th instar larvae of the western spruce budworm in central Idaho, June 22-24, 1977. Reldan was mixed with diesel fuel, with Rhodamine dye added as a marker. It was applied by a Bell 47 helicopter equipped with 8002 flat-fan nozzle tips and flying at 45 mph and 50 ft above tree tops. Spray plots were approximately 50 acres and at 4500-5500 ft elevation. Five plots were treated at each dosage rate with 5 additional plots left untreated as checks. Populations, expressed as mean number of larvae/100 buds, were determined 24 hr before spray and at 3 intervals afterwards from 15 trees in each plot.