Snow Mold
Pink Snow Mold
Gray Snow Mold
Both Pink Snow Mold and Gray Snow Mold occur in temperatures just above freezing and in moist conditions. These conditions occur most frequently under snow cover or anything that covers the lawn, such as fallen tree leaves.
Both fungi will appear as circular patches (3"- 12" or more). It’s pretty easy to tell the two apart: one has pink coloration and the other a grayish matting. Closer examination of the gray patches will reveal tiny black dots (mycelial masses) on the blades. The pink species may resemble another common disease, red thread, but occurs much earlier in the season.
Both are unsightly, but gray snow mold does not usually cause permanent damage. Pink snow mold may cause damage, particularly in the middle of the spots. However, rapid spring growth will often cause those spots to fill in on their own.
Conditions that favor the disease are excessive flush growth before the onset of winter, piles of leaves that remain on the lawn area through the winter, and/or an early snowfall. It is important to time fall fertilization so that excessive top growth is not spurred on before snowfall, and any late fall fertilization is done after top growth ceases.
Preventive applications of fungus controls, just prior to winter, are effective on lawns that have a history of severe infestations. Bear in mind that fungus control applications are not a complete cure. They simply control it through the winter.
What you can do:
Clean leaves off, or mulch them into the lawn before winter so that there are no accumulations through the dormant season.
Avoid piling too much snow on areas that have a history of problems.
If snow mold is present after snow melt, wait until the lawn dries a bit and lightly fluff up matted areas, with a leaf rake, to help air circulate and dry it out. Most snow mold will recover completely once the rapid growth starts unless it is a very serious case.
