Synthetic Pyrethroid Insecticide Efficacy Trial, 1979

Abstract

Abstract A randomized complete block design with 3 replications was used at the Southeastern Field Research Laboratory in Lancaster County, PA. Plots consisted of four 20 ft rows, each plot separated by a 5 ft alleyway. Row spacing was 34 inches and seed tubers were set 9 inches apart within rows. Certified, Class B ‘Katahdin’ seed tubers were planted Jun 7. Temi k 15G was applied in furrow at planting at 3.0 lb ai/acre. Dithane M-45 was applied at 1.5 lb ai/acre on a 5-7 day schedule for potato late blight control. The foliar insecticides were applied on Aug 9 and Sep 7 with a Meyers air blast sprayer in 50 gal of water per acre at 200 psi. Ten stems per plot were sampled weekly for all stages of Colorado potato beetle (CPB) beginning on Jul 3. Green peach aphid (MyzuspersicaeSulz.) populations were limited by an early season application of Pirimor 50WP. Two rows per plot were harvested on Oct 2b and graded by size. Precipitation totalled 2.67 inches in Jun, 5.43 inches in Jul, 3.39 inches in Aug, and 5.96 inches in Sep. Average maximum and minimum temperatures (0F) were 79.0 and 55.5 for Jun, 83.2 and 60.8 for Jul, 82.5 and 60.7 for Aug and 76.9 and 52.5 for Sep. Approximately 1.71 inches of rain fell within 3 days after the Aug 9 application which may have reduced efficacy. CPB severity was light to moderate. Insecticide application was delayed until an acceptable infestation had developed in the plots.