Effect of higher rate of quintec for the control of powdery mildew on summer squash, 2012

Authors: Krause, Charles; Horst, Leona

Submitted to: Plant Disease Management Reports
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2013
Publication Date: 8/14/2013
Citation: Krause, C.R., Horst, L. 2013. Effect of higher rate of quintec for the control of powdery mildew on summer squash, 2012. Plant Disease Management Reports. 7:V161.

Interpretive Summary:

Technical Abstract: The experiment was conducted at the Ohio Agricultural Research and Development Center’s Snyder Farm located in Wooster, OH on Wooster-Riddles silty clay loam soil, pH 6.0. On 2 May, the field was cultivated. On 15 May raised beds on 5 ft centers were prepared, laid with drip tape and plastic. On 21 May, herbicide Strategy (4 pts/A) was applied. On 22 May and 6 Jun, Roundup (42 oz/A) was applied to the field area that did not contain beds. On 4 Jun, cucumber seedlings for each variety were transplanted 1.5 ft apart into single rows 10 ft long on the beds. Starter fertilizer (N-P-K 10-34-0; 0.7 qt/50 gal water) was applied in the transplant water. Treatments were arranged in a randomized complete block design with four replications. Each treatment consisted of 7 plants spaced 1.5 ft apart with 15 ft between replications. Four broadcast applications were applied beginning on 19 Jun and ending on 17 Jul. On 26 Jun, plots were hand weeded and hoed. Treatments were broadcast applications using a CO2-pressurized backpack sprayer (30psi, 48.5 gal/A). Phytotoxicity and disease incidence of powdery mildew were evaluated on 25 Jun, 2, 9, 13, and 18 Jul using a scale of 0-100% foliage affected. Cucumber fruits from all plants in a 10 ft section from each treatment row for each variety were harvested, counted, and weighted on 9, 13 and 18 Jul. The number and weight of marketable fruit, number and weight of unmarketable fruit, and physical appearance of fruit were determined. Average minimum and maximum temperatures were 45.2 and 96.80F for 4-30 Jun and 52.7 and 97.60F for 1-19 Jul; rainfall amounts were 1.67 and 1.6 in., respectively. Plots were irrigated on with 0.15 acre inches of water on 8 Jun and 0.25 acre inches of water on 14 Jun. Analysis of variance was performed using the general linear model procedure with SAS statistical software and means were separated using Fisher’s least significant difference test. No phytotoxicity was observed on the plants for any of the Quinoxyfen treatments when compared to the control plots. Quinoxyfen had no adverse effect on fruit finish quality, number of marketable fruits, or total yield(ton/A). Powdery Mildew was first observed on squash plants on the farm on 2 Jul, but not on squash plants in this trial until after 19 Jul. Disease pressure was low for this trial from surrounding fields due to drought conditions.