Efficacy of select fungicides and fungicide programs for the management of powdery mildew on pumpkin

摘要

Two trials were conducted in the same field at The Pennsylvania State University Russell E. Larson Agricultural Research and Education Center in PA Furnace, PA, on a Hagerstown silty clay loam. Plots were plowed on 17 May, and fertilizer (N-P-K, 46-0-0 at 77 lb/A and 8-28-12 at 500 lb/A) was broadcast and incorporated. The two trials consisted of ten or seven raised beds, respectively, with 1.5-mil black-plastic mulch and a single row of drip-irrigation that were formed on 4 Jun. Raised beds were 48-in. wide and 6-in. high and were laid on 13-ft centers. For each set of three rows, the center row was an untreated guard row and the two outer rows were treatment rows. On 5 Jun, 'Sorcerer' was direct seeded, two seeds per hole, spaced 36-in. apart, onerow per bed. Plots were single rows, 20-ft long and separated by 22-ft bare plastic. Fungicide treatments were replicated four times and arranged in a randomized complete block design. Each plot consisted of six plants. Insects were managed with applications of Admire 2F (1.0 pt/A) applied with a Solo backpack sprayer (5.0 fl oz/plant) on 16 Jun. Weeds were managed with an application of Sandea 75DF (0.5 oz/A) and Poast (1.5 pt/A) plus Induce (2.0 pt/A) on 21 Jun and Gramozone (2.5 pt/A) plus Induce (2.0 pt/A) on 27 Jun. Plots were irrigated regularly and at increasing intervals as the crop matured. Fungicide applications were made using a tractor mounted, R&D CO_2 powered side boom sprayer calibrated to deliver 42 gal/A at 32 psi at the tank through6 TX-18 hollow-cone nozzles on 20-in. centers. Natural inoculum was relied upon. Powdery mildew severity was evaluated on 5, 18, 24 Aug and 1 Sep based on the percentage of upper and lower leaf surface showing symptoms on 6 leaves/plot. Rainfall totals (in.) were 6.54, 5.17, 1.97 and 0.0 for 5 to 30 Jun, Jul, Aug and 1 Sep, respectively.