Take-All Root Rot

Gaeumannomyces tritici var. graminis (syn. G. graminis var. graminis)

Warm-Season Grasses Severe Fungus

Symptoms

Irregular yellowing and thinning patches in warm-season grasses, often first appearing in spring. Roots are short, dark, and rotted. Stolons and rhizomes show dark lesions.

Irregular patches of yellowing, thinning turf that may enlarge over multiple seasons
Affected plants have short, dark-brown to black roots — "matchstick" roots
Dark lesions visible on stolons and rhizomes at or below the soil surface
Turf wilts readily under heat and drought stress due to compromised root system
Patches often recur and expand in the same locations year after year

Signs

Dark brown to black ectotrophic runner hyphae visible on the surface of infected roots and stolons — look like darkened threads running along root tissue
Hyphopodia (flattened, lobed hyphal branches used for penetration) visible on roots under magnification
No above-ground spore-producing structures — diagnosis relies on root examination

Biology

G. graminis survives in infected roots, stolons, and soil. The pathogen spreads through root-to-root contact and in infected plant material. Cool, wet soils favor infection. Root damage accumulates over time, with symptoms often most visible during summer heat stress when the damaged root system cannot meet plant water demand.

Favorable Conditions

Temperature range: 60–80°F (soil temperatures)

Wet, poorly drained soils
High soil pH (above 7.0)
Low potassium and manganese levels
Excessive phosphorus relative to other nutrients
Thatch and organic matter accumulation
Soil disturbance from construction

Cultural Practices

Adjust soil pH to 6.0–6.5 — avoid alkaline conditions that favor the pathogen
Apply acidifying fertilizers (ammonium sulfate) to reduce soil pH
Maintain adequate potassium and manganese levels via soil testing
Improve drainage through core aeration and deep tine cultivation
Reduce thatch through vertical mowing and topdressing
Avoid over-application of phosphorus
Apply granular sulfur to acidify high-pH soils

Related Reports

No published reports yet for this disease.

Reports will appear here as they are peer-reviewed and published.