Potato, Wireworm Control, Hermiston, Oregon, 1981

Abstract

Abstract The test was conducted in a solid-set, sprinkler-irrigated field at the Oregon State University Columbia Basin Agricultural Research and Extension Center to evaluate rates, formulations, and application methods of various chemicals in reducing wireworm damage to potatoes. The soil type was Ephra.ta sandy loam (Xerollic Camborthids) with an organic matter content of less than 1%. On 19 Mar, 50 soil samples were taken with a posthole digger to a depth of at least 18 inches; 4 wireworms were found for an estimated density of 0.32 wireworms/ft2. The test was conducted in a randomized split-plot design with 4 replications. The main treatments (application methods) were: preplant broadcast (BCST), at-plant sidedress (APSD), at-plant seed furrow (FURR), and postemergence sidedress (PESD). Each plot measured 38 ft long and 4 rows wide (34 inch row spacing). On 29 Apr, BCST applications were made: granules with a hand-operated Cyclone grass seeder, and liquid formulations diluted in water to a volume of 1 qt applied with a hand-held, CO2boom sprayer consisting of 4 TeeJet AL80015 nozzles at a pressure of 30 psi (25 gal/acre). The plots were rototilled to a depth of 4-6 inches within 1 h after application. On 29-30 Apr, all the plots were planted with a 2-row planter, and APSD and FURR applications were made with applicators mounted on the planter. APSD applications were shanked 3-4 inches to each side and level with the seed pieces; granules were applied as 1-inch bands with Gandy applicators, and liquid formulations were diluted in water to a volume of 1 pt, then applied at a pressure of 40 psi with TeeJet 491635 nozzles. FURR applications were made in the planter shoe and directly behind the seed pieces; granules were placed as 1-inch bands, and liquid formulations were applied with TeeJet 8004F nozzles. On 1 Jun, PESD applications wre made 2 rows at a time with tractor-mounted Gandy and liquid applicators in a manner similar to that of APSD. In 1 treatment, granules of a Temik-Phorate combination were applied over the rows, then incorporated with a Lilliston cultivator. On 6-8 Jun, tuber samples were harvested from the 2 center rows of each replicate (from ca 15 ft/row). All tubers were washed and examined for wireworm feeding, and the percentages, by weight, of tubers damaged were determined. ‘Damage’ was defined as any injury as severe as described in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes. All percentages were transformed to arcsine percentage and analyzed by analysis of variance (split-plot design) and DMRT. Materials that were not applied by all 4 application methods were not included in the analysis.