Cabbage Insect Control--2000

Eric Burkness, P.K. O’Rourke, and Bill Hutchison, Dept. of Entomology, University of Minnesota, St. Paul, Minn.

‘Gideon’ was seeded 10 Jun at the University of Minnesota Agricultural Experiment Station at Rosemount, MN, 2000. Treatments were arranged in a RCB design with 4 replications. Plots consisted of 3 rows, 25 ft (7.6 m) long with 40 inch (1.02 m) row spacing. Each replicate was separated by a 10 ft (3.04 m) alley. Treatment applications were made with a CO2 pressurized backpack sprayer using a 10 ft boom with 6 nozzles (XR-Teejet 8002 flat fan, with no screen). The sprayer was calibrated to deliver 20 gpa (187.04 l/ha) at 35 psi (242 kPa). Kinetic surfactant was added to all treatments, at a rate of 1.6 fl oz/gal (1.25 ml/liter), except the 2 rates of DPX MP062 30WG which were at a rate of 0.08 fl oz/gal (0.625 ml/liter) of Kinetic and Confirm 2F which used Latron CS-7 surfactant at a rate of 1.6 fl oz/gal (1.25 ml/liter). Four applications were made 1, 7, 14, and 21 Aug. Treatments were evaluated for CL, ICW and DBM larval infestation 10 and 29 Aug. All larval counts were taken from the middle row of each plot. Plots were harvested 30 Aug. In each treatment, 2 sets of 5 consecutive heads, with 4 wrapper leaves on each head, were harvested from the middle row and evaluated for feeding damage using Greene’s rating scale (J. Econ. Entomol. 1969 62: 798-800), where: 1=no feeding damage; 2=minor feeding damage on the wrapper leaves (0-1% eaten) with no head damage; 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=greater than 30% of the wrapper leaves eaten and numerous feeding scars on the head. The number of larval contaminants within the 4 wrapper leaves and head were also noted.

Preliminary larval counts were taken 31 Jul, indicating an average of 0.5 small ICW, 0.25 large ICW, 1.25 ICW pupae, 0.75 small CL, 0.25 medium CL, 0.25 large CL and 3.0 total DBM per 10 heads. Dominant insect pests were ICW and CL. The first sample on 10 Aug was taken after 2 applications and the second sample was taken on 29 Aug after 4 applications. On the first sample date, because of light pest pressure, there were no significant differences in control for any pest species in any treatment compared with the untreated check. For the second sample date, all treatments performed significantly better than the untreated check for control of ICW and DBM. All treatments provided significant control for total CL except Dipel, Confirm, Mustang and Proclaim. On the second sample date, all treatments provided significant control of medium and large CL, except for Dipel and Mustang treatments for medium CL. However, there were no significant differences in control for small CL, which may reflect high egg populations and continual egg hatch and/or insufficient residual control. Compared to the check, all treatments, except for Dipel and Confirm, significantly improved marketability and significantly reduced the incidence of larval contaminants. No phytotoxicity was observed.

Click here to view Table1, Control of Lepidopteran pests in cabbage: first sample date

Click here to view Table 2, Control of Lepidopteran pests in cabbage: second sample date and marketability ratings

Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@tc.umn.edu
Jeanne Ciborowski, IPM Program, Minnesota Department of Agriculture, jeanne.ciborowski@state.mn.us
Cindy Tong, Department of Horticulture, University of Minnesota, ctong@extension.umn.edu
Production Editor: Suzanne Wold, Research Specialist, University of Minnesota, woldx018@tc.umn.edu

Disclaimer
Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current directions of the manufacturer

Last Revised January 24, 2001.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer.©1999 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.