Red Thread Information

Scientific Name: Laetisaria fuciformis

Turfgrass host: Annual Bluegrass, Kentucky Bluegrass, creeping bentgrass, perennial ryegrass

Time of Year: March thru October

How To Identify Red Thread

Is your grass turning red or reddish brown? If so, your lawn is probably infected by red thread disease. Here are a few characteristics of Red Thread: Irregular and circular, ragged, light tan to pinkish patches of turf 4 to 10 inches in diameter. Red Thread normally occurs after long periods of humidity. The spots may merge to form large bleached tan or yellowish scorched areas. Fungal threads around 0.25-inch long protrude through the leaves. The threads are initially pink and later turn dry, brittle and dark red. Red Thread normally appears in the spring and fall and is more likely to appear in turf that is not maintained.

Red Thread Treatment

Red thread thrives in lawns that are not maintained well. If you have red thread in your lawn, the first step you should take is to fertilize it with a fertilizer that is high in nitrogen. The fertilizer I would recommend using is Scotts Turf Builder Weed and Feed 3. This fertilizer contains 28% Nitrogen, 3% Potash, and 7% Sulfur which will give your lawn the nutrients that it needs to prevent red thread disease from coming back again. This fertilizer is also formulated to kill weeds in your lawn, which will decrease the stress on your lawn. An easy way to spread this fertilizer on your lawn is with a Scotts Drop Spreader. Also be sure that if your lawn is infected with red thread disease that you bag all your clippings. This will prevent red thread from spreading in your grass.

Red Thread Fungicide

Cleary 3336F Fungicide is what we recommend to treat Red Thread disease in turfgrass. It is also labeled for flowers, shrubs, and trees. According to the label of Cleary 3336F, 2-4 oz of fungicide should be applied per 1000 square feet. We have had success at preventing red thread by applying 2 oz of this fungicide, and curing red thread disease using 4 oz per 1000 square feet. If you do not own a sprayer, we recommend spraying red thread disease with a Chapin Pro Series Four Gallon Backpack sprayer. When you mix the fungicide and water together, be sure that it mixed together well. 

Whenever you are spraying a fungicide, proper safety precautions should be taken into account. First, be sure that you are wearing Nitrile Chemical Resistant Gloves while mixing and spraying. Also, if the fungicide gets into your eye, it could affect your eye sight. Always wear chemical approved safety glasses.