Evaluation of fungicides for the control of Septoria leaf spot and anthracnose of processing tomatoes, 2018

摘要

The experiment was conducted at The Ohio State University Snyder Farm in Wooster, OH on Wooster Riddles silt loam. The herbicide Roundup Weather Max (1.5 qt/A) was applied on 23 Apr. The test field was plowed on 2 May and disked on 7 May. On 17 May the fertilizer 19-19-19 (N-P-K) at 300 lb/A was broadcast, top dressed, and incorporated. Tomato 'Peto 696' seeds were hot water-treated (10 min pre-soak at 100 F, soak for 25 min at 122 F) and sown on 12 Apr into 200-cell plug trays containing Baccto Professional Grower Mix. On 24 May Dual II Magnum (1.3 pt/A) and Sencor 75DF (0.7 lb/A) were applied and incorporated into the test field for weed control. Tomato seedlings were transplanted in the field on 25 May. Starter fertilizer solution (N-P-K 12-48-8;2 lb/50 gal water) was applied at transplanting. Plots were arranged in a randomized complete block design with four replications. Each plot consisted of one row of 20 plants spaced 1 ft apart with 5 ft between rows. Treated rows were alternated with non-treated border rows. Foliar treatments were applied using a tractor-mounted CO2-pressurized sprayer (40 psi, 50.6 gal/A, 2.5 mph, 40 PSI) beginning 17 Jul and ending 20 Aug for a total of eight applications. Plants were inoculated with approximately 105 spores/ml of Septoria lycopersici using a CO2 pressurized backpack sprayer on 11 Jul. The field was cultivated on 18 Jun and hoed and hand weeded on 2 Aug. Plants were overhead irrigated with 1.0 in. water on 11 and 18 Jul. The insecticide Baythroid XL(2.8 fl oz/A) Warrior II with Zeon Technology (2.0 fl oz/A) and Mustang Maxx (4.0 fl oz/A) were applied on 1 Jun; 7 and 21 Jun; and 29 Jun respectively. Foliar Septoria leaf spot incidence and severity were evaluated on 17 and 24 Jul, 2, 7, 14, 21 and 28 Aug and 4 Sep; incidence was expressed as the number of plants in each plot with Septoria leaf spot symptoms divided by the total number of plants in the plot, while severity was assessed using a scale of 0-100% foliage affected. On 30 Aug, fruits wereharvested from the middle five plants from all treated and non-treated plots. Weights of marketable fruit, fruit with anthracnose, blossom end rot, and "other" rots (minor fungal fruit rots) were measured. Average maximum temperatures for 25-31 May, Jun, Jul, Aug and 1-4 Sep were 86.6, 80.0, 84.0 79.7 and 90.4°F; average minimum temperatures were 62.3, 60.0, 61,6, 63.5 and 66.6°F; and rainfall amounts were 1.4, 3.8, 3.9, 4.4, 2.3 and 0.0 in., respectively. Analysis of variance was performed using theGLIMMIX procedure and means were separated by Fisher's least significant difference test with SAS software.