snow mold occurs in round patches of grass in the lawn. The patches contain a fussy substance (the mold), that appears in grey or pink; the most dangerous of the two. Mold is formed whenever a lot of snow is left on the lawn for a long period of time, this causes the mold to grow underneath. Late fertilization with a lot of nitrogen promotes mold. Dead grass or thatch can cause mold to develop. Gently raking allows airflow into the grass and promotes new grass growth. The putting down of grass seeds for new growth is recommended for extremely damaged lawns. Never use substances on the lawn that prevents the germination of grass seeds or fungicide; this could further damage the grass. It is also recommended not to fertilize too late in the season, to keep lawn 2 inches high and to avoid thatch build up.