Evaluation of fungicides for control of downy mildew on cucumber, Clayton 2016

摘要

The experiment was conducted at the Central Crops Research Station in Clayton, NC (N35°40.054'; W078°30.299'). Plots were single beds on 5-ft centers covered with white plastic mulch; 14-ft long with 5-ft fallow borders on each end and non-treated guard rows on each side. The previous year the field was planted with tobacco. Cucumber was direct seeded on 9 Aug (2-ft in-row spacing, 2 seed/hill) in raised beds and thinned to one plant per hill after emergence (7 plants/plot). Irrigation and fertilization (4-0-8, N-P-K) were applied via drip tape on 31 Aug, 7, 14, 21 and 28 Sep and 6 Oct. Treatments were randomized into four complete blocks. Fungicide treatments were applied using a CO2-pressurized backpack sprayer equipped with a single-nozzle, handheld boom with a hollow cone nozzle (TXVS-26) delivering 40 gal/A at 45 psi. The first three spray applications were made with a single-nozzle boom and the last one with a two-nozzle boom (19-in. spacing). Applications were made on 13, 20 and 29 Sep and5 Oct. Disease severity was assessed on 27 Sep and 5 Oct as percent leaf area with necrosis per plot. Fruit were harvested on 23 and 30 Sep and 7 Oct. Data were analyzed in the software ARM (Gylling Data Management, Brookings, SD) using analysis of variance (AOV) and the Waller-Duncan test to separate means.