Abstract
Abstract This study was conducted at the University of Arizona, Mesa Branch Station, which has a soil type of Laveen clay loam. Pelleted, Empire variety of head lettuce was planted Sep 8, in a dry seed bed with a Stanhay precision planter, 2 seed rows per 40 inch bed. The planting was furrow irrigated and kept damp until germination occurred. A complete randomized block design with 4 replicates was used. Plots were 4 beds wide, 13.2 ft and 25 ft long or .0076 acres. Sprays were applied with a CO2 pressurized back-pack sprayer with a 2 nozzle boom having D-3 tips, No. 25 cores and 50 mesh screens. This operated at 55 psi applying ca 35 gallons of spray mixture per acre. Sprays were applied at ca weekly Intervals beginning on Oct 1. Evaluation of the whitefly infestation was done by picking 5 outer leaves from each plot, 20 per treatment. A circle .2 inch in diameter was marked near the outer edge of each leaf and all the whitefly eggs and larvae within were counted under a binocular microscope. Counts for each treatment represents 4 square inches.
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