Red Thread gets its name from a pink fungus that makes the tips of affected grass appear reddish or pinkish. If lawns are in need of nitrogen and the conditions are cool and moist, the fungus may take advantage of this ideal situation and begin to grow.
This fungus otherwise known as (Laetisaria fuciformis) will almost always disappear and allow your lawn to recover once the weather begins to warm up. This is a foliar disease that usually occurs on taller mowed turf grasses during late spring, early summer and early fall seasons, commonly during humid periods where the air temperatures are between 60-75 degrees Fahrenheit. The symptoms create an undesirable appearance, but leave crowns and roots unaffected.
From a distance, symptoms appear as circular patches of tan or pink turf about 4-8 inches in diameter. The pink color is caused by the sclerotia and/or flocks of pink mycelium on leaf blades.This disease most commonly affects Kentucky bluegrass, perennial ryegrass, and tall fescue.
The most important non chemical (cultural) control option involves implementing an adequate nitrogen fertility program. This involves reviewing fall-applied nitrogen programs and considering supplemental spring-applied nitrogen on turf with a history of Red Thread outbreaks. A good fertility program implemented over two to three years should drastically reduce further problems.Water management is another important cultural practice that helps to reduce this issue. Irrigation should be deep, infrequent and done early in the morning, avoid over watering (do not water in the late afternoon or evening), provide good drainage and lastly do not let thatch levels accumulate.
In areas where Red Thread represents a chronic problem, trees may need to be pruned and or removed to improve air movement and light penetration. By improving the previously mentioned cultural conditions, the symptoms of the disease will be alleviated. One of the best ways to treat this particular grass fungus is with a balanced lawn fertilization program and specific watering habits. Even though some fungicides do suppress these types of grass diseases. In most cases, there’s no real need to use a fungicide—but that’s a decision for an expert to make, depending on the severity of the disease or as a preventative measure.
photo: John Kaminski