Effect of selected fungicides on cotton seedling disease in Alabama

摘要

Two cotton seedling disease fungicide tests were conducted at three locations on the Auburn University Tennessee Valley Substation, Wiregrass Substation and the Prattville Experiment Field in 1999. Treatments of test 1 consisted of in-furrow applications of Terraclor Super X 18.8 applied at 7.0 and 5.5 lb/A, Terraclor Super X + WGB 49 applied at 7.4 and 5.5 lb/A, Ridomil Gold PC 11G applied at 7.0 lb/A, Rovral applied at 5.0 oz/A and an untreated control. Treatments of test 2 consisted of in-furrow applications of Quadris applied at 8.35 and 5.5 fl oz/A, Terraclor applied at 7.4 fl oz/1000 ft row, Ridomil and Terraclor applied at 0.75 and 7.4 fl oz/1000 respectively, seed treatment applications of Protege + Allegiance (40ppm) + Ascend applied at 0.75 fl oz/cwt, Protege + Allegiance (40ppm) + Quadris 0.75 fl oz/cwt and an untreated control. The plots were inoculated with millet seed infested with Rhizoctonia solani and Pythium spp. At 21 and 35 days after planting significant increases in stand were observed between all fungicide treatments and the untreated control in both tests. Plant stand at 35 days after planting ranged from 2.19 to 0.43 plants per foot of row from the Terraclor Super X + WGB 49 at 7.4 lb/s and the untreated control respectively in test 1. In test 2 plant stand at 35 days after planting ranged from 1.88 to 0.46 plant per foot of row from Quadris at 8.35 fl oz/A and the untreated control respectively. Seed cotton yields in test 1 were significantly increased over the untreated control by all fungicide treatments except Terraclor Super X + WGB49 at the low rate. In test 2, seed cotton yields were also significantly increased by all fungicide treatments over the untreated control. The average fungicide cost was dollar 16.70 per acre. The average net value increase in cotton yield over the control at dollar 0.60 lb was dollar 69.70 with an average return to the producer of dollar 52.97.