ON RESEARCH
Amazing Facts About Snow Molds
Figure 1. The gray snow mold fungus Typhula incarnata produces reddish brown sclerotia up to 5 mm (0.04 in) across. Here it is attached to a dried leaf blade of creeping bentgrass.
of the regular growing season, these organisms persist in the form of sclerotia. These sclerotia are small dark compact bodies resembling poppy seeds or small mouse dropping (Figures 1 and 2) that are s the snow is melting after a long winter, you can see circular formed and built to survive conditions unfavorable for fungal patches of dead grass often matted growth. Footwear or equipment may also move together with fungal growth. These symptoms them around. are caused by snow molds, but how did the Typhula snow mold sclerotia are formed at Spore production is timed to snow mold get there and what is it doing there the end of winter on colonized plant tissues. under the snow? This article will examine the coincide with temperatures At snow melt, they fall into the thatch to wait life cycle of the fungi that cause the Typhula for cool (<10 C), wet conditions in autumn to dipping down to freezing, snow molds, specifically gray snow mold and begin growth. Under cool wet conditions, the speckled snow mold, and explore the biology sclerotia will germinate to produce stalks that since the snow provides a of these organisms. bear spores (Figure 3). Each stalk is a sexually Gray snow mold is caused by a fungus called reproductive body and can produce thousands dark, wet, and protected Typhula incarnata which is more common in upon thousands of spores. Each spore then areas with between two to three months of must make its way into the world and find environment that is just continuous snow cover. Speckled snow mold a compatible mate. For Typhula fungi, each is caused by a closely related species, Typhula right for snow mold growth. spore can mate only with a spore of a different ishikariensis, which is more common in areas sex, but since there are potentially thousands with more than three months of snow cover. of different sexes in the gene pool, nearly These organisms are active in the winter, but every spore encountered will be compatible. dormant during the summer. Throughout most of the year and all However, the limitation is that the compatible spores need to land By Dr. Tom Hsiang, Professor, Environmental Sciences, University of Guelph.
A
JUNE 2021 | ONCourse 21
