Evaluation of seed treatments and seed quality in cotton seedling disease management in Alabama, 2008

摘要

Experimental seed treatments were evaluated for the management of cotton seedling disease in a naturally infested field on the Tennessee Valley Research and Education Center in Belle Mina, AL. The field has a history of cotton seedlingdisease incidence and is colonized by Rhizoctonia solani, Pythium spp., Thielaviopsis basicola, and Fusarium spp. The soil type is a Decatur silt loam (24% sand, 49% silt, 28% clay). The seed treatments were applied to the seed by Bayer CropScience. Temik 15G (7.8 kg/ha) was applied at planting on 15 Apr in the seed furrow with chemical granular applicators attached to the planter. Orthene 90S at 0.14 kg/ha was applied to all plots as needed for thrips control. Plots consisted of 2rows, 8 m long, with 1.0 m row spacing and were arranged in a randomized complete block design with five replications. Blocks were separated by a 4.6 m wide alley. All plots were maintained throughout the season with standard herbicide,insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Plots were irrigated with a sprinkler ystem as needed. Seedling stand was determined at 2 and 4 weeks after planting on 1 May and 15May. The skip indexes were also recorded at 4 WAP. Plots were harvested on 3 Oct. Data were statistically analyzed by GLM and means compared using Fisher’s protected least significant difference test (P < 0.10). Monthly average maximumtemperatures from planting in April through harvest in October were 18.3, 25.8, 31.8, 32.8, 31.3, 31.1, and 25.6 deg C with average minimum temperatures of 3.3, 14.0, 18.8, 19.7, 19.1, 19.6, and 8.1 deg C, respectively. Rainfall accumulation for eachmonth was 0.0, 10.3, 6.8, 5.7, 12.2, 4.3, and 0.01 cm with a total of 39.2 cm.