Colorado Potato Beetle Control, 1992

Abstract

‘Katahdin’ potatoes were planted 21 May at the Fry Farm, OARDC, Wooster, OH. Plant spacing was 36 inches between rows and 9 inches between plants. Fertilizer was applied at planting (150 lb/acre 19-19-19). Two NTN 33893 soil treatments were applied at planting using a Gandy 901 Jr. insecticide applicator that delivered the insecticide into the seed furrow. The field was treated on 19 May with 0.75 lb/acre of Sencor DF which was then incorporated. Fungicide, Mancozeb at 2.0 lb/acre, was applied 19 Jul, 14, 21, and 26 Aug. Paraquat, 2 pt/acre, was applied 10 Sep as a vine killer. Plots were two rows wide and 50 ft in length, with 10 ft alleys separating plots and 10 ft alleys separating blocks. Treatments were arranged in a randomized complete block design. Foliar treatments were initiated when the first generation larvae were increasing in the plots in early Jul. The NTN 33893 foliar treatments were applied on 7 Jul only. Other foliar applications were made 7, 19 Jul 8 and 21 Aug. Foliar treatments were applied with a tractor mounted drop nozzle boom sprayer delivering 50 gal/acre at 50 psi with three D-4 hollow cone nozzles/row. Number of adults, eggs, small (instar 1-2), and large (instar 3-4) larvae were counted, and percent defoliation was visually estimated, in five lm lengths of row per plot approximately five d after each application. Potato leafhoppers (PLH) and hopperburn were sampled on 26 Sep. The number of vines with hopperburn in each of five lm lengths of row per plot was visually estimated. PLH were sampled by vacuuming five lm lengths of row per plot using a modified leafblower with a 5 inch diameter suction tube. The samples were frozen and counted under a microscope. Harvest was on 29 Sep and grading was finished by 2 Oct.