FOXGLOVE APHID CONTROL WITH SOIL AND FOLIAR APPLIED INSECTICIDES IN HEAD LETTUCE, SPRING 2003

Abstract

Lettuce was direct seeded on 14 Nov at the Yuma Valley Agricultural Center, Yuma, AZ into double row beds on 42-inch centers. Stand establishment was achieved using overhead sprinkler irrigation, furrow irrigated thereafter. Plots were 4 beds wide by 50 ft long and bordered by two untreated beds. Each treatment was replicated four times and arranged in a RCBdesign. The at-planting soil applications of Admire and Platinum were applied as a pre-plant injection at a depth of 1.5 inch below the seed line at bed shaping in 15 gpa final dilution. The side dress treatments were applied at second side dress (15 Jan) similar to fertilizer side-dressing and the materials were placed on the shoulder of the bed about 4 inch from the plant and 3 inch below the soil surface in 30 gpa final dilution. Foliar applications were made with a CO2 operated boom sprayer operated at 60 psi and 27 gpa. A directed spray (nozzles directed toward the plants) was delivered through three nozzles (TX-12) per bed. A total of three spray applications were applied on 21 Jan, 4 and 16 Feb. The first spray was initiated at early-aphid colonization 0.7 apterous aphids /plant (0.3 PA/AL, 0.2 FG, and 0.2 GPA aphids/plant; 20 % of the plants were infested with at least one aphid). An adjuvant was applied to all foliar treatments; DyneAmic on the first application and Exit on the second and third applications at 0.125% v/v. Aphid populations were assessed by estimating the number of aphids per plant in whole plant, destructive samples. Ten plants were randomly selected from each plot and placed individually into large 3-gal tubs. Each plant was sampled by visually examining all plant foliage and counting the number of apterous aphids present. At harvest (6 Mar) infestation levels of apterous aphids were estimated by randomly selecting 10 plants within each replicate, visually counting all aphids on frame/wrapper leaves and heads separately. Data were analyzed as a 1-way ANOVA using a protected LSD ( P ≤ 0.05) to distinguish treatment mean differences.