Cabbage Looper and Diamondback Moth Control on Cabbage, Spring 1991

Six week old Express’ cv. cabbage plants were transplanted on 8 May into a Bernow series fine, sandy loam soil at the Wes Watkins A.R.E.C. in Lane, OK. Single-row plots were arranged in a randomized complete block design with four replications and were 30 ft long. Rows were spaced 3 ft apart. One unplanted row between plots and 5 ft within rows were left as plot buffers. Thirty plants per plot were each spaced 12 inches apart. Trickle irrigation was used to apply recommended rates of fertilizer and meet irrigation needs. All treatments were applied with a C02-powered backpack sprayer and double-nozzle boom with TX-10 nozzles spaced 18 inches apart, directed toward the plants. The sprayer was calibrated on 28 May at 30.0 gallons per acre, 13 Jun at 28.2 GPA, and 17 Jun at 27.8 GPA. Insecticides were applied on 29 May, 7, 12, 17, 25, and 29 Jun. Five randomly selected plants per plot were sampled on 28 May, 5, 11, 14, 19, 24, and 28 Jun for CL, DBM, and other lepidopterous larvae. CL and DBM larvae were categorized as small (CL—instar 1 & 2, DBM—instar 1, 2 & 3) and large (CL—instar 3 & 4, DBM—instar 1, 2 & 3). All plots were harvested on 1 Jul and individual heads were rated using the following scale: 1 = no wrapper leaf damage, no head damage, 2 = wrapper leaf damage, no head damage, 3 = light head damage, 4 = moderate/severe head damage. Heads rated 1 or 2 were considered marketable according to U.S.D.A. standards.