Control of Grasshoppers on Rangeland with Ulv Dimethoate, 1976

An experimental ULV formulation containing 30.5% dimethoate (2.67 lb a . i . / gal) was supplied by Thompson-Hayward Chemical Company. Undiluted material was applied at 6 and 12 fluid oz (2 and 4 oz Al)/acre to 2 sq 40-acre plots per dosage near Townsend, Montana on Jul 20'76 with a Cessna Ag-wagon” aircraft using 4 or 8 Tee-jet® flat-fan. no. 8003 nozzles and 36 psi pressure. Flight speed was 120 mph, and flight height and swath spacrng both were 100 ft . Results were assessed by counting grasshoppers in sixty 0.1-m2 subsamples (delineated by wire rings)/plot on July 14, 22, 26, and 29. The species listed above comprised 35, 23, 20, and 7% of the pretreatment infestation, respectively; 5 additional species were present in smaller numbers. The infestation was 86% adults and 14% numphs (4th and 5th instar).