Brigitte,
I need to know what kind of grass you are growing and what part of the country it is in.

Hi Kris, I dont know the Type of Grass, I live in Orting,WA and we have lots of Rain….

There’s a good chance that your grass has a fungal disease either red thread or pink patch. Red thread is especially prevalent in the Pacific Northwest in the spring and fall. Both red thread and pink patch have similar symptoms and are active in cooler, humid wet climates. The fungal disease occurs in grass that is deficient in fertility. For starters a good fertility program based on a soil test will promote a healthy lawn and reduce red thread. Mow often at the recommended height to remove diseased grass blades. Fungicide are not recommended for home lawns. There are additional cultural practices to cotrol the fungus . For more info go to http://www.ipm.uiuc.edu/diseases/series400/rpd413/#top or http://www.agry.purdue.edu/turf/publicat.htm

You have to treat crabgrass in the spring when the weather gets warm. In the midwest, it is recommended to treat the lawn around early May when the crabgrass starts to grow and before it makes any seeds.