Evaluation of fungicide programs for management of downy mildew of processing cucumber - Trial 3, 2018

摘要

The experiment was conducted at the University of Delaware's Thurmond Adams Research Farm, Carvel Research and Education Center near Georgetown. The experiment was a split plot with the fungicide program as the main plot (five programs and a non-treated control) and five cultivars (susceptible 'Vlaspik' + 'Sire' pollinizer; susceptible 'Expedition' + 'Sire' pollinizer; moderately resistant 'Citadel' + 'SV2789CL' pollinizer; improved moderately resistant 'Peacemaker' + 'SV2789CL' pollinizer, and moderately resistant 'SVCN6404' + 'SV2789CL' pollinizer) as the subplot. Plots were arranged in a randomized complete block design with four replications. Main plots consisted of twelve rows, two rows of each of the five cultivars and an additional two rows of Vlaspik, with 2.5 ft between rows. The main plots were 18 ft long. Plots were seeded with a Monosem planter at 60,000 plants/A on 3 Aug. Fungicides were applied using a battery operated backpack sprayer (30 psi; 50 gal/A) at the 2-4 leaf stage on 17 Aug, at flop on 28 Aug, or both times. The trial was overhead irrigated as needed. Disease severity on the leaf at the fourth node on two plants per plot was assessed as the percent leaf area with sporulation, necrosis, or water soaking due to downy mildewon 5 Sep. Analysis of variance was conducted using the MIXED procedure of the Statistical Analysis System (version 9.4; SAS Institute, Cary, NC). Fixed effects were cultivar (main plot) and fungicide treatment (subplot), and replication was treated as arandom effect. Means were separated according to Fisher's protected least significant difference (LSD) test (a = 0.05).