Red thread is most common to Fescues, Ryegrasses, and Kentucky Bluegrasses during times of moist and cool weather. Red Thread gets its name from the pinkish-red threads that form around the leaf blades and bind them together. Eventually, the affected grass will turn brown and the red treads will be most visible when wet. The best prevention for red thread is to aerate often and remove thatch. Mowing to proper levels, reducing shade on lawn, and following a fertilization schedule can also help.