Red Thread is a fungal disease that affects turfgrass in cooler, more humid conditions, particularly in spring and fall.
Red Thread gets its name from the pink to red antler-like structures (sclerotia) that form at the end of the infected grass blades. As the disease progresses, small (4 to 8 inches), circular dead patches with a pinkish or tan cast appear in the lawn. It most commonly affects Kentucky Bluegrass, Perennial Ryegrass, and Tall Fescue.
Fertilize regularly. Properly fertilized lawns are less susceptible to Red Thread. Learn some basics on How To Fertilize Your Lawn.