ABSTRACT

A survey was conducted on 84 cotton fields in the Northern High Plains of Texas. Seed emergence was increased from and average of 24 % without seed treatment to an average of 72 % when a fungicide active against Pythium was added to the seed. When seed was treated with Vitavax-PCNB, but not treated with a Pythium active material, then seed emergence averaged 59 %. Seed emergence averaged 79 % when a complete fungicide package was used with activity against Thielaviopsis basicola, R. solani, and Pythium spp. Emergence of cotton seed was similar for first-year cotton fields as for fields with at least three years of cotton production. Emergence when seed was not protected against Pythium was poorest for fields in a corn or grain rotation than for fields in a rotation with peanut or sorghum. Hypocotyl injury was slightly increased with increasing years of cotton production, and percent root necrosis was greatly increased with multiple years of cotton production. Pythium spp., T. basicola, and R. solani were isolated from root or hypocotyls lesions in 39, 36, and 5 % of the fields, respectively.