Snow mold is a term that describes several different cold weather diseases on turf.
“Snow mold” is a bit misleading in that snow is not a prerequisite for all of these diseases to occur; the most common snow mold, Microdochium patch, simply needs cold, damp weather. Microdochium patch, often called pink snow mold, is caused by Microdocium nivale.
All turfgrass species are susceptible, especially on low-cut, high maintenance turf stands. Symptoms are round patches of disease turf following extended cold, wet or humid weather patterns.
Patches may enlarge if the weather pattern persists, and occasionally the patches may have a pink to a reddish color on the margins.
For control, consider the following:
1. Encourage a low soil pH to discourage Microdochium patch development.
2. If possible, postpone nitrogen applications until the turf has gone dormant to discourage an abundance of tender foliage. A balanced fertility program throughout the season will help keep turf healthy and more disease resistant.
3. Fungicides are essential for preventive control, as with most turf diseases. A combination of systemic and contact fungicides is ideal, such as Tourney Fungicide tank mixed with chlorothalonil. To best prevent Microdochium patch, applications before leaf growth has stopped in the fall are preferable to maximize plant uptake and protection of the systemic fungicide. A second application prior to snowfall is advisable, followed by subsequent applications mid-winter if possible.