The Colorful Cool Season Culprit Red thread (also known as pink patch) is one of the easiest lawn diseases to spot because it sports a distinctive pinkish red coloration. Especially serious in the Pacific Northwest, red thread also appears in stands of cool season grasses over a wide region when weather conditions are right.

When Green Lawns Turn 'Red'

Red thread lawn disease grows most aggressively when temperatures are in the 68 to 75 degree range and during extended periods of wet or very humid weather. Even though this may seem like a narrow "window" or set of circumstances for disease activity, red thread can overtake a turf area fast. Besides temperature, red thread gets a helping hand from certain nutritional imbalances, too. This lawn disease takes off much faster when there's a lack of nitrogen, for instance. Low levels of calcium (or lime) also affect some grass types.

Damage Symptoms: What Red Thread Looks Like And Does

The symptoms of red thread lawn disease first appear as "water soaked" darkened irregular areas from just a few inches to several feet across. These areas gradually become bleached or tan colored. Healthy plants are usually interspersed with diseased plants, giving the lawn an over-all ragged look. As the red thread becomes well developed, light pink to red fungus strands (or threads) 1/4'' or more in length begin to grow from the tips of the blades and the leaf sheaths — these threads are the reason for the disease's common name. The wind moves bits of these threads to non-infected plants to spread the disease. The threads can also touch nearby blades to spread the infection. Red thread lawn disease very seldom wipes out an entire stand of turf, and so infected lawns will often have an uneven or patchy appearance.

Cultural Management: You Can't Change The Weather

Like most grass diseases, red thread is very much weather related. When conditions are right for development, management of red thread is limited to checking and correcting any nutritional deficiencies or direct treatment with a fungicide material. Lawn treatments with fungicides are usually effective, and one or two maintenance applications in the spring and again in the fall are adequate in most situations for control. If you have seen signs of red thread on your turf, please contact your neighborhood Spring Green. We’re always ready to help with managing disease diseases, so you can have the best lawn possible. 

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