Bacillus Formulations for Cabbage Looper Control on Head Lettuce, 1979

Abstract

Abstract This trial was carried out at the University of Arizona, Mesa Branch Station, where the soil type is Laveen clay loam. Empire variety of lettuce (naked seed) was planted in a dry seed bed, 2 seed rows per 40 inch wide bed using a sled type planter on Aug 22, 1979. The planting was furrow irrigated, keeping the beds damp until germination took place. Average tempera-tures for this period were, maximum 101°F and minimum 72.5°F. Plants were thinned to a 12 inch spacing on Sep 24 and 25, after which the planting was cultivated, side dressed with nitrogen fertilizer and irrigated. In order to protect the seedlings after thinning the entire planting was treated with Lannate at 0.45 lbs ai/acre. Plots were laid out in a complete randomized block design with treatments replicated 4 times. Each plot was 4 beds wide, 13.3 ft by 30 ft long, representing 0.0092 acres. Four ft alleyways were left between plots lengthwise of the field. Treatments with different materials began on Sep 21, with applications being made at approximately weekly intervals. Sprays were applied with a CO2 pressurized bak-pak sprayer having a lightweight 2 nozzle boom, with one nozzle per plant row. Each nozzle was fitted with a D-3 tip. No. 25 core and 50 mesh screen, operated at 55 psi and applying 35 gallons of spray per acre. When the plants became larger, 2 nozzles per plant row were used. Insect counts were made on 10 plants selected at random from the middle 2 beds of each plot. Each plant was examined for eggs and larvae of the cabbage looper, Trichoplusiani. At maturity the lettuce plants in the middle 2 beds of each plot were graded in the field according to commercial grades (i.e., no. 1 1/2, no. 2, and no. 2 1/2 which represents the number of heads that are packed in a standard lettuce carton).