Control of Colorado Potato Beetle on Potatoes, 1983

Abstract

Abstract Two experiments were conducted at Yakima, Washington to evaluate insecticides for control of the Colorado potato beetle (CPB): One against first generation larvae (from the overwintering), and the other against first generation adults. Potatoes were planted on 13 Apr in Ritzville silt loam soil (Mesic Calciorthidic Haploxerolls) pH 6.2 and organic matter 1.6% at Yakima, Washington. The insecticides were applied with a 2-row 4-nozzle portable boom, CO, powered sprayer at 50 psi in 50 gal of water per acre. Each plot was 2 rows (34 inch) wide and 25 ft long. Each treatment was replicated 4 times in a randomized complete block design. There were no untreated check plots. At the time of the first experiment, applied on 9 Jun, the potato plants were infested with 2nd, 3rd and 4th stages of CPB larvae, but few adults. At the time of the second experiment, applied 10 Jul, the plants were infested with newly emerged adults of the 1st generation, but few larvae. The potatos were normally sprinkler irrigated with ca. 0.75 acre inch of water applied at 5 to 7-day intervals, but was not irrigated the first 7 days after treatment. The foliage on the 2-row plots was agitated with the hand to dislodge the insects and the number of dead and live CPB larvae or adults per m2 of soil surface per plot were counted on 10 Jun (24 h posttreatment) first experiment, on 11 Jul second experiment. The % control for each plot was calculated based on the number of dead and live CPB adults or larvae found on the soil surface. The % defoliation was estimated (10 Jun) to determine the severity of CPB infestation in the plots. The number of CPB adults and larvae on the plants in 6-row ft per plot were counted 3 days posttreatment to determine the number of insects surviving the treatment and returning to the plants.