Snow Mold Control

In regions of the northern United States, the most important and devastating diseases are the snow mold diseases.  The two most common are Typhula blight and Microdochium patch.  Two less common, but found primarily in the western regions of the United States known as Coprinus snow mold and Snow scald can occur.  Below is a brief description of each.   Chemical control of the two major snow mold diseases can be found below.    

Typhula blight (Typhula incarnata), a common snow mold, is first evident at snowmelt in late winter. Symptoms appear as circular areas of straw to grayish brown turf. The turf may also appear matted with the appearance of a grayish-white mycelium at time of snowmelt. The mycelium often dries and becomes encrusted over the patch.

A diagnostic key to Typhula blight is the appearance of small hard spherical fruiting structures called sclerotia. Often times these sclerotia appear reddish to reddish-brown in color.

Microdochium patch (synonyms: Pink snow mold, fusarium patch) is probably the most common snow mold and is often associated with Typhula blight. Pink snow mold is the term used when this disease occurs with snow melts, while fusarium patch is used for the disease in the absence of snow. In both cases the organism causing the disease is Microdochium nivale. Circular patches of pinkish-orange to brown infected turf are common symptoms.

Coprinus (Coprinus psychromorbidus) snow mold occurs most often in the Rocky Mountains where extended periods of deep snow cover occur. The pathogen is considered a low-temperature basidiomycete, thus the term “low temperature basidiomycete” is often used to describe this disease. Two strains exist of the pathogen one that produces sclerotia and the other does not.

Snow scald (Myriosclerotinia borealis) is most prevalent on ground that is frozen under deep snow.  Symptoms appear as circular to irregular shaped patches that have bleached or white leaves with sclerotia that turn black. 

 With both Coprinus snow mold and snow scald, promoting early spring melt will help reduce disease severity.

Snow Mold Fungicides

In regions of the United States where snow mold diseases are a serious problem, preventative fall treatments are generally the most effective.  Depending on the region or climatic conditions, the type of snow mold that can occur varies.  The major types of snow molds are listed below.

SDHI – Succinate dehydrogenase Inhibors/carboximides

DMI – Demethylation Inhibitors/ Triazoles

QOL – Quinone Outside Inhibitors/ Strobilurins

About the author

Dr. Karl Danneberger is a professor of Turfgrass Science at The Ohio State University. Dr. Danneberger's contact information can be found here. You may also follow Dr. Danneberger on Twitter: @GlobalTurf