Evaluation of fungicides for the control of downy mildew and Phytophthora blight of winter squash, 2007

摘要

The experiment was conducted at the Ohio Agricultural Research and Development Center’s Muck Crops Agricultural Research Station in Celeryville, OH on Linwood muck soil, pH 5.2. Fertilizer (18-17-17, 500 lb/A) was incorporated into the test field on2 May. Plots were disked, leveled and raised beds on 6 ft centers were prepared on 11 Jun. ‘Taybelle PM’ (resistant to powdery mildew) squash seeds were sown on 25 May into 72-cell plug trays containing Scott’s 360 Metro seedling mix. Squash seedlingswere transplanted on 12 Jun. Plots were arranged in a randomized complete block design with four replications. Each plot consisted of one row with 15 plants spaced 2 ft apart on 6 ft centers. Treatment rows were alternated with untreated guard rows. Treatments were applied using a tractor mounted 3.0 hitch (hydraulic attach) motor driven sprayer (95 psi, 56.3 gal/A, 2 mph) on a 7 day schedule beginning 2 Jul and ending 28 Aug for a total of eight applications. Ranman 400SC (2.75 fl oz/A) and Omega 500F(1.5 pt/A) treatments were drenched at transplanting by applying 50 ml of fungicide solution within a 6 in.-diam circle around the base of each plant using a backpack CO2-pressurized sprayer. The insecticide Sevin XLR Plus (1 qt/A) was applied on 25 Jun, 3, 12, 18, and 31 Jul. To control powdery mildew, Procure 480SC (8 fl oz/A) was applied to the entire test field on 7, 17, and 30 Aug. Plants were overhead irrigated with 0.5 in. water on 12, 14, and 22 Jun. The severity of downy mildew was evaluated on 16, 23, and 30 Aug using a scale of 0-100 percent foliage affected. Fruit were harvested from seven plants from the center of each treatment row on 6 Sep, and the number and weight of marketable fruit and fruit with Phytophthora blight were determined.Average maximum temperatures for 12-30 Jun, Jul, Aug, 1-6 Sep were 82.8, 80.9, 82.4 and 85.3deg F; average minimum temperatures were 58.2, 57.6, 62.9 and 55.0deg F; and rainfall amounts were 0.55, 4.50, 6.33 and 0.00 in., respectively. Data were analyzed by ANOVA using SAS statistical software.