Red Thread, Laetisaria fuciformis

IPM Steps to Reduce Red Thread

1. Sample for Pest

Confirm the presence of red thread before you treat.

Where to find it while inspecting: You will see red or pink areas on leaf blades—visible without magnification. Appears similar to other leaf fungal diseases but the presence of “red threads” are clear indicator of this disease.

2. Proper ID

Is it red thread?

Size and Appearance: Affected turf will appear in clumps, generally circles of discolored areas from 4–8" in diameter.

3. Learn the Pest Biology

What is the life cycle of red thread?

Life Cycle: Fungus overwinters in thatch and soil as pink sclerotia.

Preferred Food Sources: Fungal diseases break down organic matter as a nutrient source.

Preferred Habitat: Slow-growing turfgrass with reduced sun exposure or air movement.

4. Determine Threshold

How much red thread is too much?

Threshold: The threshold for red thread fungus disease is dependent upon the aesthetic needs, and playability (safe footing) of the turfgrass field. It may remain dormant until conditions are favorable (extended periods of high humidity). If those conditions change you may not need to act. After prolonged periods of disease development, the patches may merge to produce large irregularly shaped areas of damaged turf, so base your actions on projected weather conditions.

5. Choose Tactics

Creating a healthy soil condition and understanding turfgrass’s needs is the first step in reducing turf pests. What can I do to treat, reduce, or prevent red thread?

Best Management Practices: Soil tests will help determine the fertility of turfgrass—verify turf is getting adequate nutrition (potassium, phosphorus, calcium) as well as nitrogen, maintain soil pH between 6.0 and 6.5, water deeply and infrequently, don’t water in evening or when weather suggests prolong periods of leaf wetness, keep mower blades sharpened, collect mower mulch when disease is active, rather than incorporate back into the turf. An application of water-soluble nitrogen reduces disease severity.

Treatment Methods: Fungicide treatments may be an option in extreme cases, where allowed by law.

6. Evaluate

Was the tactic successful? Record the date pests were first noted, and the tactic you used, and its success. Use one of our RECORD KEEPING tools.

For More Information:

Cornell Cooperative Extension Horticulture Diagnostic Laboratory: Red Thread on Turfgrass

Remember:

When a pesticide application is necessary, all necessary and required precautions are taken to minimize risk to people and the environment and to minimize risk of pesticide resistance or pest resurgence. Pesticide use in your school may be prohibited or regulated by local policies or state and federal regulations. Risk reduction methods can include, but are not limited to, spot-treatment, the use of gel or paste bait formulations placed in inaccessible locations, injection into a crack or crevice, and other methods that reduce potential exposure.