Cabbage Looper and Beet Armyworm Control on Head Lettuce, 1979

The trial was conducted at the University of Arizona, Mesa Branch Station, with a soil type of Laveen Clay Loam. Empire variety of lettuce (naked seed) was planted in a dry seed bed, Aug 22, 1979, 2 seed rows per 40 inch bed, using a sled type planter. The planting was furrow irrigated, keeping the beds damp until germination took place. Average daily temperatures at this time were maximum - 101°F, minimum - 72.5°F. Plants were thinned to a 12 inch spacing on Sep 24 and 25, after which they were cultivated, side dressed with nitrogen fertilizer and irrigated. Plots were 4 beds wide, 13.3 ft by 30 ft long. A complete randomized block design was used, with all treatments replicated 4 times. Treatments were applied as foliar sprays using a 2 gallon CO2 pressurized, bak-pak hand sprayer having a lightweight 2 nozzle boom operating at 55 psi. A single hollow cone nozzle per plant row was used when the plants were small. As plants increased in size, 2 hollow cone nozzles were used for each plant row. Egg and larval counts were made at approximately weekly intervals beginning on Sep 25 from the middle 2 beds of each plot. Ten plants at random were examined for eggs and larvae. Yield data were obtained from the middle 2 beds of each plot (4 plant rows). Total number of plants in 2 beds was recorded and the mature heads were graded according to #l 1/2, #2 and #2 1/2 sized heads. These numbers indicate the number of heads that are packed in a standard lettuce shipping carton.