Corn - D. Longicornis Control, Experimental Insecticides, 1975

Corn, variety OYO 220, was planted at Wooster, Ohio, on several dates (see tables for exact date). Soil insecticides were applied at planting in a 7-inch band in front of the presswheel or in the seed furrow with Gandy granular insecticide boxes mounted on a 2-row John Deere corn planter. All applications were made at a ground speed of 3 mph. Plots were 1 or 2 rows wide, 40 ft long, with 2 border rows between replications that were contiguous and 25 ft alleyways between replicates that were not. Because of variation in larval population, the number of rows in a replication is usually less than 30. A randomized complete block design was used. Soil was a silt loam. Rainfall for May was near normal with June and July below normal. Soil temperatures were typical for this period. Treatments were evaluated by removing 24 root systems from each treatment and rating the rootworm damage to each root system on a scale of 1-6 (1 = no damage; 4 = 1 node of roots (or equivalent) destroyed; 6 = 3 or more nodes of roots destroyed). These ratings were made July 28 to August 5.