Efficacy of Registered and Experimental Insecticides for Control of Black Cutworm Larvae, 1996

Corn was planted in 30-inch rows in 6 Sep. The experimental design was a RCB with four replications. Each plot was 4 rows wide X 60 ft long. Insecti cides were applied at planting-time, pre-emergence (9 Sep), and as rescue treatments (18 Sep). They were evaluated for the control of black cutworm (BCW) under artificial infestation. On 17 Sep, corn plants were infested with BCW larvae within barrier arenas that were 36 ft2. Fifteen laboratory-reareci BCW third to fourth instars were placed in the center of each arena. Granular insecticides were metered through Noble units mounted on each of the planter units (John Deere, 7000 series, 4-row Max-emerge planter). Granules were applied as a 7-inch band ahead of the firming wheels. Spring tines mounted be hind each planter unit were used to incorporate the insecticide into the soil. Planting-time applications of Lorsban 4E were delivered with 8002 nozzles ai 5.75 gpa in a 7-inch band at 25 psi at a speed of 5 mph. Pre-emergence treatments were applied as a broadcast spray over 2 rows with a CO2 back-pack sprayer system calibrated to deliver 13.1 gpa at 23 psi. Rescue treatments were applied as a broadcast spray over 2 rows using the same calibrations. A CO2 back-pack sprayer system was used for the pre-emergence treatments. The cumulative number of cut plants was determined 3, 7, 10, and 14 days af ter infestation (DAI). The condition of each plant cut by BCW larvae was determined to be either “dead” or “recovered” from previous cutting on 14 DAI