Control of Colorado Potato Beetle on Potato, 1987

Abstract

Abstract The trials were conducted in Lancaster County, Landisville, Pa. Certified class B 'Katahdin' seed potatoes were planted on 30 May with 9 inch spacing between plants and 34 inches between rows. Plot were 4 rows by 25 ft with 2 border rows arranged in a randomized complete block design with 4 replicates. Temik 15 G (1.0 lb [AI]/acre) was applied in furrow at planting for all treatments. The control received Temik at planting, however, no foliar treatment was applied to the plot. The foliar insecticides were applied on 24 Jun, 16, 30 Jul, and 11 Aug with a George White boom sprayer delivering 30 gal/acre at 27 psi. Border rows were sprayed with Asana (0.0735 lb [AI]/acre) on 26 Jun by hand, and with the boom sprayer on later dates. A Tx-18 type spray nozzle with a 50 mesh screen was used, with the tractor speed at 3 mph. Ten stems per plot were sampled immediately before and 24 h after spraying, with all stages of Colorado potato beetle being sampled. A subjective damage index was implemented beginning on 2 Jul: 1 indicating 0-5% leaf loss to 5 indicating >75% defoliation. Two 25 ft rows/plot were harvested on 25 Sep, and graded by size 2 weeks later. Average maximum and minimum daily temperatures (degree fahrenheit) were 76.2° and 49.3° for May, 89.6° and 59.1° for Jun, 89.0° and 63.5° for Jul, and 85.5° and 58.5° for Aug, respectively. Rainfall totals were 3.62 inches in May, 1.88 inches in Jun, 2.85 inches in Jul, and 1.99 inches in Aug. Precipitation for May was 0.04 inches above normal. Jun precipitation was 2.22 inches below normal. Jul precipitation was 1.52 inches below normal. Aug precipitation was 1.62 inches below normal. A factor affecting the trials was drought stress (precipitation for May through Aug was 5.32 inches below normal).