snow mold
noun Plant Pathology.
a disease of cereals and other grasses, characterized by a dense, cottony growth that covers the affected parts as the snow melts in the spring, caused by any of several fungi of the genera Calonectria, Fusarium, Pythium, and Typhula.
any fungus causing this disease.
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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019