Microbial and Insecticidal Control of Lepidopteran Pests in Minnesota Cabbage, 1995

Abstract

This study was conducted at the University of Minnesota Rosemount Agricultural Experiment Station. Cabbage was transplanted 14 Jun. Plots consisted of two 25 ft (7.6 m) rows on 40 inch (1.0 m) centers with plants spaced 13 inches (0.33 m) apart. Ten ft (3.0 m) borders and 10 ft (3.0 m) alleys separated the plots. Treatments were arranged in a RCB design with 4 replications. Treatment applications were not initiated until early head formation because of mechanical problems with the sprayer. Treatments were applied 2, 10, and 21 Aug using a moderate-clearance Spirit sprayer with 3 TX-10 hollowcone nozzles (1 overhead and 2 drop nozzles) per row. The sprayer was calibrated to deliver 27 gpa (252.5 liters/ha) at 47 psi (3.3 kg/cm2) and 3 mph (4.8 km/hr). Bond sticker/extender was added to all treatments at a rate of 0.10 fi oz/gal (0.8 ml/liter). Counts were taken 7 and 23 Aug. Plots were harvested and evaluated for feeding damage on 25 Aug using Greene’s rating scale (J. Econ. Entomol. 1969 62:4 798-800). 1 = no feeding damage; 2 = minor feeding damage on the wrapper leaves (≤ 1% eaten); 3 = moderate feeding damage on the wrapper leaves (2-5% eaten) with no head damage; 4 = moderate feeding damage on the wrapper leaves (6-10% eaten) and minor feeding scars on the head; 5 = moderate to heavy feeding on the wrapper leaves (11-30% eaten) and moderate feeding scars on the head; 6 = > 30% of the wrapper leaves eaten and numerous feeding scars on the head.