Source: Penn State Extension
This winter has brought long-term snow coverage in many parts of the Commonwealth, much like the winter of 2014. In conditions like these, we are more likely to see snow molds affecting our wheat, barley or rye plantings. In Pennsylvania, snow molds typically do not cause much economic damage, but it’s worth knowing about them ahead of time in case you need to make a diagnosis for your crop.
There are a few different types of fungi responsible, but in each case they are favored by snowfall early in the season, followed by deep snow on unfrozen ground. Beneath the snow cover, the fungi will first attack the oldest leaves that are touching the ground, and can ultimately move into the crown of the plant and cause some real damage. Plants do recover through the season if the crown is not killed. The snow molds tend to be most active when temperatures are just above freezing (under a foot of snow, ground temperature is usually around 41 degrees).
To scout for snow molds, target the areas of the field with the deepest snow cover (more than 1 foot). As these areas melt for the first time, you may be able to see the mold itself as a pink, fuzzy growth on dead or dying leaves. Another type of fungus may cause surrounding snow to have a green color as it breaks down the tissue of the leaf. A close inspection of affected leaf tissue may reveal dark colored fungal bodies that give a speckled appearance to the leaves.
There are no chemical control options available for snow molds, but rotating to legumes reduces the amount of fungus for future crops. Some resistant cultivars may be available. Earlier planted fields will survive better under snow mold attack because the larger plants are more resistant to infection and they are typically able to resume growth in the spring more vigorously than their younger counterparts.
For more information on snow molds and to view some pictures, please see this Utah State University publication.