Wireworm Control on Potato, Hermiston, Or, 1983

Tests were conducted in a solid-set sprinkler-irrigated field of potatoes to evaluate the effectiveness of different formulations and rates of chemicals applied by different methods in reducing wireworm damage. The soil type was Adkins fine sandy loam (Xerollic Camborthid) with a pH of 6.6-7.8 and an organic matter content of 0.5-1%. On 8 Mar, eight wireworms were found in 50 soil samples obtained in the test area with a posthole digger to a depth of at least 18 inches. On 14 Apr, preplant broadcast (PPB) applications of granules were made with a hand-operated Ortho Whirlybird spreader, and the plots rototilled to a depth of 4-6 inches within 1 h after application. On 25-26 Apr, at-plant sidedress (APSD) applications were made with Gandy applicators mounted on the planter by placing the granules in 1-inch bands shanked 3-4 inches to each side and level with the seed pieces. Similarly, at-plant seed-piece furrow (APF) applications were made by placing granules in 1-inch bands in the planter shoe, level with and directly ahead of the seed pieces. On 24 May, posteinergence sidedress (PESD) applications were made with tractor-mounted Gandy applicators in a manner similar to APSD. On the same day, posteinergence topical incorporated (PETI) applications were made by allowing granules to fall over the plants from the end of the delivery tube to which a spreader was attached, and all plots were similarly treated with Temik 15G (3 lb (AI)/ acre) for aphid control. Plots were then hilled with a Lilliston cultivator immediately after treatment. Each plot measured 38 ft long and 11.3 ft wide (4 rows, 34-inch spacing), and each treatment was replicated 4 times in a randomized complete block design. On 4-5 Oct, tuber samples were harvested from the 2 center rows of each plot (ca. 15 ft/row). Expressed as percentages of tubers by weight, an injured tuber was one with any wireworm feeding, and a damaged tuber was one with any injury as severe as described in Sec. 51.1560 and 51.1564 of the U.S. Standards for Grades of Potatoes.