Turf Health: ID and control of Red Thread

What is Red Thread?
by Cheryl Cone

Red thread is a common disease in lawns of western Oregon and Washington. Diseased areas of lawn vary in size and shape and appear scorched. This time of year you will often see red at the tips of the dead grass, thus the name “red thread.” Red thread occurs during the cool, wet periods from fall until spring and is caused by a combination of two fungi. Only the leaves and leaf sheaths are attacked. Lawns that are growing slowly because of the lack of nitrogen are most severely affected. Red thread is seldom serious enough to kill the lawn.
 

How Can I Identify Red Thread?
Red thread can be identified by circular, irregular yellow patches in the lawn from between 2” to 24” inches in diameter that become dead and brown in appearance. During moist weather pink webs bind the grass blades together. When the blades dry, small, pink, hornlike fruiting bodies of fungus about ½” long protrude from the diseased leaf tips.

How Do I Treat Red Thread?
Most lawns will improve with an application of high nitrogen fertilizer. If the disease persists it can be useful to have the soil pH tested and apply lime if needed per the recommended application rates. Where red thread has been a problem in the past, maintain a soil pH of 6.5 to 7.0. ?In the case of severe infections the lawn may need to be sprayed with several applications of fungicide.
Good lawn maintenance practices also help counter red thread. Keep the lawn properly fertilized and avoid overwatering. Apply water during the early morning hours so that the lawn has a chance to dry out during the day. Also, avoid allowing thatch to accumulate.