Smother out snow mold

October 9, 2019 -  By
Snow mold damage (Photo: PBI-Gordon Corp.)

Cold lover Snow mold typically develops during winter when temps are low and moisture is high. (Photo: PBI-Gordon Corp.)

There are two types of snow mold that lawn care operators (LCOs) should be on the lookout for: pink snow mold, caused by the ascomycete fungus microdochium nivale, and gray snow mold, caused by two basidiomycete fungi, typhula incarnata and typhula ishikariensis.

Take a look at a few ways to spot — and control — the persistent disease.

Identification: Snow mold is a fungus that grows and develops on turfgrass during the winter season when temperatures are considerably cooler and moisture is abundant.

Gray snow mold damage is observed as patches several inches to several feet in diameter. Damage is seen when snow cover recedes in the spring and aerial mycelia are often observed near melting snow. The affected turf may be tan in color, matted and may become brittle when it dries out. Small spherical structures called sclerotia — which range in color from pink to brown to black — can also be observed on the leaf sheaths.

Pink snow mold features circular, tan patches that are up to 6 inches in diameter and slightly matted down. The patches may appear pink in sunny conditions.

While pink snow mold doesn’t require snow cover to occur, gray snow mold typically develops only after at least 60 to 90 days of snow cover. Cool-season turfgrass is most susceptible, including annual bluegrass and creeping bentgrass.

Treatment: To prevent snow mold development, avoid excessive leaf growth via fertilization and heavy nitrogen applications late in the season. LCOs also can remove excessive thatch accumulation and continue to mow turf at the end of the growing season to maintain a lower canopy (at about 3 inches).

If snow mold symptoms are evident after spring green up, raking matted areas after snow melts can enhance drying and encourage new plant growth. Severely damaged turf may require seeding or resodding. LCOs can also lightly fertilize affected areas.

In extreme cases, LCOs may want to consider a program of both cultural practices and preventive fall snow mold fungicide applications.

Applicators should be sure to refer to fungicides’ labels to determine which products are labeled for use in their respective areas. Tank-mix or premix products with more than one mode of action are often most effective in controlling both types of snow mold.

Sources: Matt Giese, technical services manager, Syngenta; Brian Aynardi, Ph.D., Northeast research scientist at PBI-Gordon Corp.

Sarah Webb

About the Author:

Sarah Webb is Landscape Management's associate editor. She holds a bachelor’s degree from Wittenberg University, where she studied journalism and Spanish. Prior to her role at LM, Sarah was an intern for Cleveland Magazine and a writing tutor.

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