Summary of cotton seedling disease in Missouri.

Predominant Seedling Disease Complex Attacking Missouri Cotton: Four types of fungi that live in the soil may attack and damage cotton in most Missouri fields: Rhizoctonia solani, Fusarium species, Thielaviopsis basicola, and Pythium species.

Estimates of Yield Loss to Seedling Diseases in Missouri During 2004: Scientists estimated that 4.0% of the 2004 Missouri cotton crop was lost to seedling diseases. This amounted to 27,600 bales of lost yield valued at $7.9 million.

Average Yield Loss from 2000 through 2004 to Seedling Diseases in Missouri: An annual average of 4.75% of the Missouri cotton crop was lost to seedling diseases from 2000 through 2004. This resulted in an average annual loss of 32,800 bales valued at $9.4 million.

Recent Research Activities: The objective of our recent research was to determine the usefulness of infurrow fungicides for protecting early season planted cotton against seedling diseases. An experiment was conducted with 3 planting dates during the last 3 years. The plots were established at the University of Missouri research farm near Portageville. Cotton was planted on 3 dates: April 20-25, May 1-5, and May 10-15. Plots were treated with Ridomil Gold 4 EC (0.15 oz./1000 row ft) and Quadris 2.08 SC (0.6 oz./1000 row ft) infurrow or not treated. The number of living seedlings per plot was determined at 14 and 28 days after emergence (DAE). Roots of seedlings were evaluated for seedling disease symptoms at 14 DAE, and seed cotton was harvested at maturity to determine yield. The results indicated that seedling disease severity was greater for the early than the later planted plots, seedlings were healthier in early planted plots treated with infurrow fungicides than not treated, and yields were greater for the early than late planted plots especially when treated with infurrow fungicides.