Effect of bacterial leaf spot severity on crop yield of processing tomato, 2018

摘要

The experiment was conducted at The Ohio State University, OARDC North Central Agricultural Research Station in Fremont, OH on Hoytville silty clay loam soil. Tomato 'Peto 696' seeds were hot water-treated (10 min pre-soak at 100 °F, and treatment for 25 min at 122 °F) on 6 Apr and sown on 10 Apr into 288-cell plug trays containing Baccto Professional Grower Mix. Potash (500 lb/A), monoammonium phosphate (150 lb/A), and urea (250 lb/A) were broadcast and incorporated on 28 May. Beds (33 in. wide and 5 in. high) were formed on 30 May. The herbicides Dual Magnum (20 oz/A) and Sencor (0.33 lb/A), Matrix (2 oz/A) and Metribuzin (5 oz/A), and Roundup Power Max (32 oz/A) and Choice (8 oz/A) were applied on 31 May, 2, and 9 Jul respectively. Tomato seedlings (7th true-leaf stage) were moved outside on 14 May for 3 weeks (average high 81°F and average low 59 °F) to be hardened off before being transplanted into the field. Tomato seedlings were transplanted into the field on 1 Jun. Transplants were spaced 1 ft apart and starter fertilizer (N-P-K 10-34-0; 0.7 qt/50 gal of water) was applied at the time of transplant. The experiment included: 1) non-inoculated plots treated with an industry standard chemical spray program, 2) plots inoculated with a high(~108 CFU/ml) concentration of Xanthomonas perforans strain Xcv-761 and no chemical control treatment, 3) plots inoculated with a low (~104 CFU/ml) concentration of X. perforans strain Xcv-761 and no chemical control treatment, and 4) non-inoculated non-treated control plots. Plots were arranged in a randomized complete block design with eight replications.To control fungal and oomycete diseases Orondis Opti (2 pt/A) was applied on 26 Jun, Bravo Weather Stik (1 lb/A) on 5 and 19 Jul, 2 Aug, and 4 Sep, and Quadris Top (6 fl oz/A) on 13 and 26 Jul, 13 Aug, and 7 Sep. To manage insect pests or mites, Mustang Maxx (4 oz/A) was applied on 26 Jun, Warrior II (1.90 oz/A) on 19 and 30 Jul, Coragen (8 oz/A) on 23 Jul, Asana (9.60 oz/A) on 2 Aug, and Assail (4 oz/A) and Radiant (8oz/A) on 29 Aug. Treatments and inoculum were applied using a CO2 backpack sprayer at 40 psi equipped with an orange nozzle calibrated to an average of 70 GPA. Plots were inoculated until runoff with 104 CFU/ml (low concentration) on 25 Jun and 6 Jul or108 CFU/ml (high concentration) on 25 Jun, 6, 12, and 20 Jul. Plants were overhead irrigated with 0.6 in. of water on 3 Aug. Foliar bacterial leaf spot (BLS) disease severity and incidence were assessed every 7-10 days on the center eight plants starting on 19 Jul and ending on 6 Sep. Foliar BLS disease severity was rated using a scale of 0-100% foliage affected. Fruit were harvested from the center five plants on 11 Sep when 90% of the fruit were red. Fruit were sorted into two categories (fruit withBLS and fruit with other diseases), counted, and weighed. Average maximum temperatures were 80.8 °F from in Jun, 84.1 °F in Jul, 83.1 °F in Aug, and 79.4 °F from 1 to 11 Sep. Average minimum temperatures were 62.7 °F in Jun, 63.2 °F in Jul, 64.1 °F in Aug, and 64.9 °F from 1 to 11 Sep. Total rainfall amounts were 2.3 in. in Jun, 1.4 in. in Jul, 3.7 in. in Aug, and 0.4 in. from 1 to 11 Sep. Foliar disease severity data were transformed with the arcsine function (arcsine ]/(f oliar severity/100)]), AUDPC with base-10 logs, and marketable yield data were square root transformed. Analysis of variance was performed using the GLIMMIX procedure and transformed means were separated by Fisher's least significant difference test with SAS software (version 9.4). Kruskal-Wallis non-parametric analysis was performed for total fruit with BLS and medians were separated with the Mood's Median test using Minitab (version 17). Pearson correlation coefficients were determined with a linear regression analysis ofthe marketable yield and the foliar BLS severity estimated on the last day of foliar evaluation.