Location: Application Technology Research Unit
Title: Evaluation of quintec for the control of powdery mildew and bacterial spot on fresh market tomato, 2012 Authors
Submitted to: Plant Disease Management Reports
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2013
Publication Date: August 14, 2013
Citation: Krause, C.R., Horst, L. 2013. Evaluation of quintec for the control of powdery mildew and bacterial spot on fresh market tomato, 2012. Plant Disease Management Reports. 7:V159. Technical Abstract: The experiment was conducted at the Ohio Agricultural Research and Development Center’s North Central Agricultural Research Station located in Fremont, OH located on Rimer loamy fine sand soil, pH 6.1. On 29 Mar, the field was cultivated. On 5 Apr 2012, 7 lbs/A 14.3% granular boron, 300 lbs/A 0-0-60 (N-P-K), 150 lbs/A10-52-0 (N-P-K) and 200 lbs/A 46-0-0-(N-P-K) were incorporated into the test field that was chisel plowed on 18 Oct 2011. On 5 Apr raised beds on 5 ft centers were prepared. On 11 May, herbicides Roundup powermax (22 oz/A) and Request (12.8 oz/A) were applied. Additional herbicides Dual magnum (1 pt/A) and Graamoxone (2 pt/A) plus crop oil (31 oz/A) were applied 17 and 23 May, respectively. On 30 May, pepper transplants 1 ft apart into single rows 20 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 20 plants spaced 1 foot apart with 5 feet between rows. Treatment rows were alternated with untreated border rows. 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 10 plants spaced 2 ft apart with 5 ft between rows and 15 ft between replications. Treatment rows were alternated with untreated border rows. Insecticides Spintor at 10 oz/A, Asana at 8 oz/A, Lanate LV at 2 pt/A, Spintor at 8 oz/A and Coragen at 5 oz/A were applied on 8, 20 Jun, 5 and 18 Jul, and 2 Aug, respectively. On 4, 12, 27 Jun and 1 Aug, plots were hand weeded and hoed. Four broadcast applications were applied beginning on 20 Jun and ending on 12 Jul. Treatments were directed foliar applications using a directed nozzle apparatus on sprayer (30psi, 44.5 gal/A). Plants were inoculated with approximately 108 CFU/fl oz (3x108 CFU/ml) of Xanthomonas campestris pv. Vesicatoria strains 110C and 767 in the evening of 27 Jun using a CO2-pressurized backpack sprayer (30 psi, 56.2 gal/A). Phytotoxicity and disease incidence of powdery mildew and bacterial spot were evaluated on 3, 12, 17, 24, and 31 Jul, 7 and 15 Aug using a scale of 0-100% foliage affected. Tomato fruits were harvested from 5 plants chosen at random from each treatment row on 15 and 22 Aug. The number and weight of marketable fruit, marketable fruit with bacterial spot, green fruit, and green fruit with bacterial spot were determined. Average minimum and maximum temperatures were 54.1 and 83.90F for 14-31 May, 57.7 and 82.90F for1-30 Jun, 69.2 and 87.10F for 1-31 Jul, and 62.8 and 79.40F for 1-22 Aug; rainfall amounts were 1.43, 1.95, 0.95, and 2.88 in., respectively. Plots were irrigated on with 0.9 inches of water on 12 and 29 Jun and 13 Jul and 1.1 inches of water on 27 Jul. 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. Powdery Mildew was first observed on squash plants on the farm on 2 Jul, but was not found on tomato plants until after trial ended. Mildew disease pressure was low for this trial from surrounding fields due to drought conditions. Bacterial spot disease pressure was high for this trial from surrounding fields as well as from inoculated plants. By the end of the study, the untreated control had an average of 22.5% diseased foliage (leaves, stems, petioles). Both levels of Quintec significantly reduced bacterial spot severity at the end of the season when compared to the control, but did not differ from one another in efficacy. Area Under the Disease Progress Curve (AUDPC) values were significantly lower in both levels of Quintec compared to the untreated control (P=0.0001). None of the treatments increased the percentage of marketable fruit (data not shown), yield per acre, or marketable fruit in ton/A when compared to the untreated control.