Aerial Application of Microbials and Permethrin for Control of Second-Generation Ecb Larvae in Minnesota, 1990

This test was conducted near Glencoe, Minn., in a 60-acre production field planted 2 Jun for processed sweet corn. All treatments were applied with 4 gal water/acre at 28 psi by helicopter traveling at 55 mph. The helicopter was equipped with #8, 1/4 inch Raindrop Dellavin nozzles mounted on a 45 ft boom with an effective swath width of 50 ft. Each treated area consisted of 150 (3 swaths) by 1200 ft strips (4.1 acres). Because this was a commercial production field, it was not possible to have an untreated check. Commencing with first-silk and the onset of the second-generation ECB moth flight, treatments were applied 8, 15 and 24 Aug. The unplanned 9-day spray interval between 2nd and 3rd applications resulted from excessive fog on 21 and 22 Aug. All treatments were evaluated 31 Aug by examining 100 ears/treatment for total larvae, large larvae (fourth & fifth instars) and location of feeding damage. Stratified random sampling was used to select 4 sets of 25 ears each from 4 blocks within the middle 50 ft swath of each treatment.