- Pest Type: Disease
- Crops Affected: Wheat, winter, Wheat, spring, Wheat, Barley
- Scientific Name: Gaeumannomyces graminis
Diseased plants usually occur in localized, more or less circular, areas up to several feet in diameter. Affected plants are severely stunted, lose their green color, and rapidly become bleached. A black, scruffy mold appears on lower stems and roots. Roots, crowns, and stem bases have brown to black dry rot - a diagnostic characteristic. A dark brown or black mat of coarse fungus hypahe may be found under the lower leaf sheaths. Infected plants die prematurely, with unfilled white heads.
Severity of this disease, especially the crown and basal rots, varies greatly from year to year in the same field. This fungus lives in the soil on diseased straw and root residues. Runner hyphae grow from the residue to roots of wheat plants. When certain forage grasses are grown in rotation (esp. bromegrass and wheatgrass), this fungus builds up in the soil. Planting wheat after such grasses can result in severe crop loss. Nitrate fertilizers favor the build-up of this disease, as does cool and moist soil in the fall and spring.
Sanitation - remove affected crop residues, grassy weeds, and volunteer grains. Do not plant wheat after bromegrass, wheatgrass, or barley. If this fungus builds up in the soil, rotate to crops other than cereals and forage grasses for at least 3 years. Maintain balanced soil fertility levels and use ammonium forms of N for spring top-dress. Avoid early planting. Appropriate seed treatment fungicides may be beneficial. If this disease becomes a problem in your area, contact local advisers regarding best control measures.