Synthetic Pyrethroid Insecticide Efficacy Trial, 1980

Abstract

Abstract At the Southeastern Field Research Laboratory, Lancaster County, PA a randomized complete block design with 4 replications was used. Plots consisted of four 24 ft rows planted 34 inches apart. Certified, Class B ‘Norchip’ seed potatoes were planted on May 8, with a 9 inch spacing between plants. Two rows of corn were planted along each plot to reduce drift. Temik 15 G (3.0 lb ai/acre) was applied in furrow at planting. Dithane M-45 was applied at 1.5 lb ai/acre on a 5-7 day schedule for potato late blight control. Pirimor 50 WP was applied early in the season to eliminate green peach aphid (Myzus persicaeSulz.) populations. The foliar insecticides were applied Jul 3, 21, Aug 13, and 28 with a Myers air blast sprayer in 50 gal of water per acre at 200 psi. Ten stems per plot were sampled each wk for all stages of Colorado potato beetle (CPB) beginning Jun 29. A subjective damage estimate was also assessed, 1 for little or no damage through, 5 for more than 75% defoliation. Two rows per plot were harvested Sep 22 and graded by size. Rainfall totalled 5.03 inches for Jun, 3.65 inches for Jul, and 2.64 inches for Aug. Maximum and minimum average daily temperatures (0F) were 80.5 and 53.5 for Jun, 87.8 and 61.9 for Jul and 87.8 and 62.5 for Aug. Approximately 0.74 inches of rain followed the Jul 21 application, and temperatures were above 85 F on this date and Aug 25 which may have effected efficacy of these compounds.