Synthetic Pyrethroid Insecticide Efficacy Trial, 1982

Certified, Class B ‘Norchip’ seed potatoes were planted 6 May with a 9-in spacing between plants. A randomized complete block design with four replications was used. Plots consisted of four 20-ft rows planted 34 in apart. Temik 15G (1.0 lb (AI)/acre) was applied in-furrow at planting for all treatments and the control. A 3.0 lb (AI)/acre Temik treatment was also included. Starting 8 Jun., Dithane M-45 was applied at 1.5 lb (AI)/acre on a 5 to 7 day schedule for potato late blight control. The foliar insecticides were applied 6 and 27 Jul., with a Myers air blast sprayer in 50 gal. of water per acre at 200 lb/in2. Forty stems per plot were sampled each week for all stages of Colorado potato beetle (CPB) beginning 25 Jun. A subjective damage estimate was also assessed. Two rows per plot were harvested 30 Aug. and graded by size. Rainfall totalled 8.36 in for June, 2.74 in for Jul. and 1.10 in for Aug. Average maximum and minimum daily temperatures (°F) were 78.2 and 56.7 for Jun., 86.0 and 62.3 for Jul., and 82.5 and 56.2 for Aug.