Potato, Wireworm Control, Hermiston, Oregon, 1982

Abstract

Abstract A test was conducted in a solid-set, sprinkler-irrigated field at the Oregon State Univ. Columbia Basin Agric. Res. Cent. The soil type was Adkins fine sandy loam (Xerollic Camborthids) with an organic matter content of less than 1%. On 13 Mar., 50 soil samples were obtained with a posthole digger to a depth of at least 18 inches; 11 wireworms were found for an estimated density of 0.88 wireworms/ft2 . The application methods were: preplant broadcast (BCST), at-plant sidedress (APSD), seed-piece furrow (FURR), and postemergence sidedress (PESD). However, not all chemicals were applied by all four methods. Each plot measured 40 ft long and 11.3 ft wide (four rows; 34-inch rows), and each treatment was replicated 3 times, in a randomized complete block design. On 4 May, BCST applications were made; granules were applied with a hand-operated Cyclone grass seeder, and liquid formulations were diluted in water to a volume of 1 qt and applied with handheld, two-row boom sprayer consisting of 4 TeeJet (No. AL80015) nozzles at a rate of 24 gal/acre at a pressure of 30 lb/in2. The treated plots were rototilled to a depth of 4 to 6 inches within 1 h after application. On 4-5 May, potatoes were planted with a two-row planter, and APSD and FURR applications were made with applicators mounted on the planter. Sidedress applications were shanked 3 to 4 inches to each side and level with the seed pieces; granules were applied in 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 (No. 4916-35) nozzles attached to the rear of the shanks. Furrow applications were made in the planter shoe, level with and directly ahead of the seed pieces; granules were placed in 1-inch bands, and liquid formulations were applied with TeeJet (No. 8004E) nozzles. On 8 June, PESD applications were made two rows at a time with a tractormounted Gandy and liquid applications in a manner similar to that of APSD. The Temik + phorate treatment was a formulation consisting of these two compounds, while the Temik + Mocap and Temik + Dyfonate treatments were separate formulations combined during application. Before the layby operation on 9 June, phorate granules were applied topically over the rows in one treatment. All plots were similarly treated with Temik (3 lb (AI)/acre), except those that had already received Temik and those that were treated with Dyfonate (2 lb (AI)/acre) or phorate as FURR or PESD. All plots were then hilled with a rotary cultivator. On 5-6 Oct., tuber samples were harvested from the two center rows of each plot (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. Since significant differences in percentages of damaged tubers among the untreated checks were noted, the percentages were converted to percentages of check before they were analyzed by ANOVA and DMRT.