Red Thread (note the light red hue to the damaged grass blades) is a cool-season disease that is controlled by applying nitrogen. Green-Up is an excellent fertilizer to apply to red thread in the early spring. Pink in color, red thread spreads by pustules “exploding “and spitting fungal material up to 8 feet. This is why red thread damage seems to jump from spot to spot.
After it rains, there’s typically more water available in the soil for the grass plants. When plants take up that water, they are also taking up nitrogen that’s in the soil. The more it rains, the faster that nitrogen is used up. If the nitrogen is not replenished, the problem will continue.