Evaluation of resistance of pepper cultivars to Pseudomonas leaf spot, 2009.

摘要

Seventeen pepper cultivars were evaluated for resistance to Pseudomonas leaf spot on foliage in a field trail on Wooster silt loam at the Ohio Agricultural Research and Development Center, Snyder Farm in Wooster. Prior to planting, 200 lb/A 19-19-19 (N-P-K) were broadcast, top dressed and incorporated into the test field on 26 May. Pepper seeds were treated by agitating them in a 20% Clorox (1.2% sodium hypochlorite) solution for 1 min, followed by a 5 min rinse in running tap water and air-drying. Seeds were sown on 24 Apr into 200-cell plug trays containing Fafard seedling mix. The herbicides Roundup (1 qt/A), Poast (1 pt/A), and Treflan 4EC (1.5 pt/A) were applied and incorporated on 17 Apr, 6 Jun, and 8 Jun, respectively. Pepper seedlings were transplanted on 9 Jun; starter fertilizer (N-P-K 9-45-15; 3 lb/55 gal water) was applied at transplanting. Plots were arranged in a randomized complete block design with four replications. Each plot consisted of 20 plants spaced 1 ft apart on 5 ft centers. On 17 Jul, peppers were side dressed with 100 lb/A calcium nitrate (15.5-0-0, 19% calcium). Warrior with Zeon Technology (3 fl oz/A) and Baythroid XL (1 oz fl/A) were applied on 25 Jun and 17 Jul, respectively for insect pest control. Plants were inoculated with approximately 109 CFU/fl oz (108 CFU/ml) Pseudomonas syringae pv. syringae strain SM20-01 on 26 Jun using a tractor-mounted CO2-pressurized sprayer (40 psi, 50.3 gal/A, 3 mph). Plants were overhead-irrigated with 1.0 in. water on 16 Jun and 15Jul. The field was cultivated and hand weeded on 17 Aug. Severity of Pseudomonas leaf spot on foliage was evaluated on 2, 9, 16 and 22 Jul and 5 and 14 Aug using a scale of 0-100% foliage affected. Average maximum temperatures for 9-30 Jun, Jul, and 1-14 Aug were 83.3, 78.1, and 81.3degF; average minimum temperatures were 58.1, 56.5, and 59.6degF; and rainfall amounts were 2.6, 4.1, and 2.8 in., respectively. Analysis of variance was performed for experiment using the general linear models (GLM) procedure, and means were separated by the least significant difference (LSD) test with SAS software.