Control of Wireworms with Soil Insecticides and Seed Treatments, 1990

Abstract

Abstract We established 2 wireworm trials in field corn, one at Assumption (Christian County) and the other at Hutsonville (Crawford County). The Assumption site had been a permanent pasture until 10 yr ago, and wireworms have been a problem for the last 6 yr. Three wireworm baits (each a 2-oz mixture of wheat and corn buried 4-6 inches deep) were placed in this field in early spring. An average of 4 wireworms/bait station was found in the germinating seed-baits 3 wk after baiting. The Hutsonville site had been used as set-aside acreage in 1987 and had been planted to soybeans and corn in 1988 and 1989, respectively. An average of 12 wireworms was found in each of the 3 bait stations in this field. The experimental designs were randomized complete block with 4 replications at Assumption and 6 at Hutsonville. Treatments were applied to single rows (50-ft long at Assumption and 85-ft long at Hutsonville) with 30-inch row spacing. Granular insecticides were applied with Noble units mounted on each of the planter units (John Deere 7000 series, 4-row max-emergence planter). Granules were applied in-furrow or in a 7- inch band ahead of the firming wheels and were incorporated into the soil. Seed treatments were mixed with seed on the day of planting. Following corn emergence, stand counts (in 17.3 ft of row) and 2 trench soil samples were taken from each plot. A soil sample consisted of a trench of soil 3.3 ft (length) × 4 inches (width) × 4 inches (depth) that was removed and sifted from each row. The number of live wireworm larvae was recorded for each trench sample. In addition, seeds/seedlings in each 3.3 ft of row were examined for wireworm damage and rated according to the following scale; (1) seed/seedling undamaged, (2) seed/seedling damaged but plant established, (3) seed/seedling damaged, with plant showing some signs of stress, and (4) seed/seedling damaged, with no plant establishment. The percentage of damaged plants was calculated from the rating scale. Before ANOVA, wireworm data were transformed by square root (x + 0.5) and percent damage data were transformed by arcsine [square root (%/100)]. Untransformed data are presented.