Evaluation of fungicides and trellising for the control of downy mildew and Phytophthora fruit rot of cucumber

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 5.6). The field was disked on 30 Apr. Fertilizer containing nitrogen (200 lb/ANH_4NO_3), phosphorous (150 lb/A P_2O_5), and potassium (300 lb/A K_2O) was incorporated and the field was plowed on 1 May. Seeds of the slicing cucumber 'Dasher II' were sown on 6 May into 72-cell plug trays containing Metromix 360. The field was disked, leveled, and raised beds were prepared on 5 Jun. The herbicide Makaze (22 fl oz/A) was applied and incorporated into the test field on 23 Apr and 23 May and the herbicides Curbit EC (3 pt/A) and Command 3 ME (1pt/A) were applied on 5 Jun. The field was cultivated on 20 Jun, and 12 and 16 Aug, and hand weeded on 24 and 26 Jun and 3, 18, and 22 Jul and 1 and 16 Aug. The insecticides Mustang Max (4 fl oz/A) and Sevin XLR Plus (1 qt/A) were applied on 12 Jun; 19, 26 Jun; 3, 15, 22 and 29 Jul; 5 Aug, respectively. Cucumber seedlings were transplanted on 5 Jun. Treatments were arranged in a randomized complete block design with 4 replications. Each treatment consisted of 1 row with 10 plants spaced 2 ft apart on 6 ft centers. Treatment rows were alternated with non-treated ground production guard rows. Six-ft wooden stakes and trellis string were placed in the trellised plots on 2 Jul. Downy mildew was first observed on 24 Jul (disease severity 3.8% in the non-treated control). Treatments were applied using a tractor mounted 3.0 hitch (hydraulic attached) motor driven sprayer (40 psi, 29.1 gal/A, 2 mph) beginning 16 Jul and ending 21 Aug for a total of 6 applications for products applied on a 7-day schedule and 4 applications for those applied on a 10-day schedule. The severity of downy mildew on foliage was evaluated on 24 and 31 Jul and 7, 14 and 21 Aug using a scale of 0-100% foliage affected and the Area Under the Disease Progress Curve (AUDPC) was calculated. Cucumber fruits from all plants of each treatment were harvested, counted and weighed on 24 and 31 Jul, and 7, 14 and 21 Aug. Average maximum temperatures for 5-30 Jun, Jul and 1-21 Aug were 79.1, 81.2 and 77.5°F; average minimum temperatures were 63.4, 62.9 and 56.9°F; and total rainfallamounts were 2.8, 9.2 and 2.3 in., respectively. Analysis of variance was performed using the general linear models procedure with SAS statistical software and means were separated using Fisher's least significant difference test.