Synthetic Pyrethroid Sprays for Control of Colorado Potato Beetle on Potatoes, 1981

Abstract

Abstract ‘Russet Burbank’ potatoes were planted on Apr 22, in Ritzville silt loam soil (Mesic Calciorthidic Haploxerolls) pH 6.2 and organic matter 1.6% at Yakima, WA. The synthetic pyrethroid insecticides were applied with a 2-row, portable boom CO2 powered sprayer at 50 psi in 50 gal of water per acre to the foliage of potatoes on Jul 1 and Jul 22. Monitor was used as a standard treatment. There were no untreated check plots, because of the severe infestation of Colorado potato beetles (CPB) at the time of insecticide application. Each plot was 2 rows (34 inches) wide and 19 ft long. Each treatment was replicated 4 times in a randomized complete block design. The potato crop was sprinkler irrigated with 0.75 acre inch at 7 to 10 day intervals. The foliage on the 2 row plots was brushed with the hand to dislodge the insects and the number of dead and live CPB per sq m of soil surface per plot were counted on Jul 2 and Jul 23 (24 hrs post-treatment). The number of CPB adults and larvae on the plants in 15 row ft. (2 rows 7.5 ft) per plot were counted on Jul 2, 15, 22 and Jul 30 and Aug 7. The percent defoliation by CPB was estimated per plot on Jul 2 (starting point), Jul 15, and Jul 22, and Aug 4 and 7.