Foliar Insecticide Efficacy Trial, 1983

Abstract

Abstract Certified, Class B ‘Katahdin’ seed potatoes were planted 10 May, with a 9-inch spacing between plants. A randomized complete block design with 4 replications was used. Plots consisted of four 25-ft rows planted at 34 inches apart Temik 15 G (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 in Jun, 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 28 Jun and 26 Jul, 3, 18 Aug with a George White boom sprayer in 22 gal per acre at 66 psi. Ten stems per plot were sampled before and after sprays for all stages of CPB. Control plots were sampled weekly beginning 13 Jun. A subjective damage estimate was also assessed, 1 for little or no damage through 5 for more than 75% defoliation. One 20 ft row per plot was harvested 18 Oct and graded by size. Rainfall totalled 2.89 inches for Jun, .28 inches for Jul and 3.27 inches for Aug. Avg max and min daily temperatues (°F) were 83.1 and 57.5 for Jun, 89.8 and 60.1 for Jul and 89.2 and 61.4 for Aug.