Evaluation of fungicides for the control of downy mildew in pickling cucumber, 2007.

摘要

The trial was conducted on a Bojac fine sandy loam soil (organic matter <1%) at Virginia Tech’s Eastern Shore Agricultural Research and Extension Center, Painter, VA. Fertilizer was applied at the rate of 75 lb/A N, broadcast incorporated before bedswere formed on 11 Apr. This is equivalent to 150 lb/A nitrogen after bed formation. Beds were fumigated with 50:50 methyl bromide/chloropicrin at rate of 200 lb/A and covered with plastic and trickle tubing on 24 Apr. Cucumbers were seeded on 16 Aug. During the growing season standard recommended practices for weed and insect control were followed. Irrigation was provided through trickle tubing when needed. Plots consisted of single, 20-ft rows spaced 6-ft apart and bordered by staked tomatoes. Treatments were replicated four times and arranged in a randomized complete block design. Treatments were applied with a tractor mounted CO2-pressurized sprayer that was calibrated to deliver 40 gal/A at 40 psi. The spray boom consisted of three nozzles spaced20 inches apart and fitted with 11004 twin jet nozzles. The two outer nozzles were mounted on 15-in drop tubes. Sprays were applied on 4, 10, 14, 21, and 28 Sep. Powdery mildew was controlled in the entire trial with weekly sprays of Quintec 2SC at 4 floz/A alternated with Nova 40W at 5 oz/A. Downy mildew incidence (percentage of leaves infected) and severity (percent of leaf surface infected) ratings were taken on 14, 25 Sep and 4 Oct. Cucumbers were hand-harvested, sized, and weighed on 11 Oct. Oversized pickles weighing greater than 0.5 lb were removed and assigned a 0.2 lb weight.