Control of Wireworms on Field Corn, 1989

Abstract

Abstract An experiment was conducted on 20 May in Northumberland County, VA to determine the effects of several commercially-available granular insecticides and a seed treatment for controlling wireworms on germinating corn seeds. The cropping history for this field included no-till soybeans planted in the spring of 1987 with no subsequent fall planting of a cover crop. In 1988, field corn was planted followed by a fall planting of crimson clover. Soil type for this field is characterized as a Suffolk fine sandy loam. A pretreatment sample of corn seeds (var. Pioneer 3184) from 30 separate, 3.3-ft row sections was made on 12 May to determine the level of wireworm feeding damage in the recently-planted field. Of the 146 seeds that were found, 71 (48.6%) exhibited feeding damage. Because of the severity of the damage the grower was forced to replant; however, in a portion of the field that was not replanted we conducted a randomized complete block experiment with 5 replicates and 7 treatments. Each plot consisted of a single, 15-ft row in which furrows were hand dug to a uniform depth of approximately 1.5 inches. Seeds were spaced 6 inches apart within the furrows providing about 30 seeds/plot, or 150 seeds/treatment overall. Each block was separated from adjacent blocks by a distance of 6.3 ft. All granular insecticides were applied in-furrow using pint canning jars (Mason) with lids in which a single opening had been drilled. Lid openings were laboratory-calibrated to deliver accurately the labeled rate for each insecticide while walking at 3 mph. The possibility of mixing one or more insecticides was avoided by using a separate jar and lid for each treatment. For the treatments involving Agrox D-L Plus, the labeled rate of 2 oz product/bushel of corn seed was used. On 4 Jun entire-plot stand counts were made, and on 5 Jun, the roots and attached seed for each corn seedling, as well as seeds which had not germinated, were removed from the soil and inspected for evidence of feeding damage.