Monitoring Pseudoperonospora cubensis sensitivity to fungicides, 2014

摘要

The experiment was conducted at the Ohio Agricultural Research and Development Center's in Wooster, OH. Cucumber seeds (var. Lafayette) were planted individually in 4" square pots containing Baccto Professional Grower's Mix in a greenhouse on 12 Aug.The experiment was set up in a randomized complete block design with four replications; each replication consisted of one single plant. Seeded pots were hand watered and fertilized with 10-10-10 every 3 to 4 days from germination through the end of the experiment. When the second seedling leaf was fully expanded on27 Aug, fungicide treatments were applied to the top surface of the first and second true leaves (0.08 fl oz of fungicide solution to the top surface of each leaf) using a hand held sprayer containing the fungicide at the label rate. Calculation of eachtreatment rate was based on 55 gallons per acre. On28 Aug, the treated seedlings were placed in a 15 cell-carrying tray and transported in a covered truck to Ohio fields with sporulating downy mildew lesions in Wooster (cucumber), Celeryville (cucumber) and Fremont (squash). After 24 hours, seedlings were returned to the greenhouse in Wooster to monitor downy mildew development and phytotoxicity on the leaves. Severity of downy mildew was evaluated 15 Sep by using a scale of 0-100% foliage affected. Seedlings were maintained in a greenhouse from a low of 70°F at night to high of 75°F during the day. Analysis of variance was performed using the generalized linear mixed models procedure with SAS statistical software and means were separated by the least significant difference (LSD) test.