What Is Snow Mold?

Snow mold is a fungal disease that develops in the winter months and can wreak havoc on your lawn in early spring, or even well into summer. It's not something you want to ignore, as it can cause severe damage if left untreated. Knowing what snow mold looks like and how to treat it will go a long way in protecting your lawn from this troublesome disease. If you want to have the best looking lawn in Utah after snow melts away, this is the blog post for you!

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The most obvious symptom of snow mold is the presence of its infamous circular patches in your lawn. These infected areas are often a grayish-white color, and may appear slightly raised above the rest of the grass. They can range in size from just a few inches to several feet across. There may also be white fuzz or webbing on top of these patches, which is actually an accumulation of fungal spores that give off that characteristic “snowy” appearance. The grass around and underneath the infected areas will become thin and discolored.

Look For These:

• White-gray or pink-gray color
• Infected circular patches
• Size ranging from a few inches to a few feet
• Fuzzy "webbing" across grass when damp
• Hardened sclerotia when dry
• Occasional fruiting bodies (not always)

To truly identify snow mold, you must first understand the difference between the two main types of snow mold you may encounter in your lawn. Gray and pink snow mold are caused by different types of fungi, and they attack your lawn in different ways. Gray snow mod if the more common of the two, but a pink snow mold infection is much more severe.

• Gray Snow Mold: This variety of the lawn disease, also known as Typhula blight, is caused by fungi in the Typhula genus, and it is the more common variety of the two. The fungi within this genus only attack the grass blades of your lawn, and you can positively identify gray snow mold by waiting until your lawn dries. If the infected areas develop hardened, antler-like sclerotia as your lawn dries and warms up, you are dealing with gray snow mold.

• Pink Snow Mold (pictured above): Though not as common, this type of the disease causes much more damage to your lawn, as the fungi responsible attack the roots and crowns of your grass. Pink snow mold, also called Fusarium patch, is caused by the fungal species called Microdochium nivalis. If you see a faint pink perimeter around the infected area in your lawn, you are likely dealing with the dreaded pink snow mold!

The true "causes" of snow mold are the aforementioned fungi, but these invasive fungi can only develop under certain conditions. Gray snow mold develops best when the soil and air temperature is right around freezing, or just slightly above. Pink snow mold will develop at a much wider range of temperatures, anywhere from 20-80 ˚F, whereas gray snow mold thrives in warmer temperatures, meaning you may see signs of snow mold well into late spring or even throughout summer.

Of course, the number one cause of both types of snow mold is a heavy blanket of snow. It is under the cover of this blanket where snow mold develops. Cold, damp fall weather leading into winter is the most common cause of both types of snow mold. This disease typically spreads underneath snow cover, but pink mold can develop even without snow. Excess shade and overfertilizing in late fall (especially in conjunction with one another) frequently contribute to snow mold.

Snow mold can kill grass if it’s left untreated for an extended period of time, but generally speaking, basic treatments can help clear up snow mold entirely. As the fungus spreads into the roots and crowns of your lawn in some cases, it begins to damage these important parts of your grass plants. This causes them to be very vulnerable to other diseases and pests, as well as severe environmental conditions.

• The Pink Death! Remember that gray snow mold is considered a foliar disease because it only attacks the leaves of plants, which is easily treatable. The pink stuff will ravage every part of your lawn and directly kill your grass. Do not waste another second if you see signs of pink snow mold -- call a lawn care provider before it's too late!

The best way to prevent snow mold is to get your lawn in order before the first snowfall or frost of the season. Many fungicides in big-box stores will not work well on common gray snow mold in spring, so the best treatments are all preventive, which is true of all lawn diseases. Make sure your lawn is draining well, gets ample sunlight, and does not receive too much nitrogen-heavy fertilizer in fall.

If you wake up one spring morning and see signs of snow mold developing across your lawn in Utah, your best option is to call Holmes Lawn & Pest! We have been combating snow mold in the Salt Lake area for years, and we know exactly what your lawn needs. We will leave you with a list of a few more ways you can prevent snow mold, and hopefully you will never need us… but call us at (801) 616-5296 if you do!

Tips For Snow Mold Prevention:

• Mow 1 inch lower than usual just before the first frost.
• Rake up leaves and thatch where snow mold can attach itself.
• Use a season-appropriate, low-nitrogen fertilizer in fall.
• Move obstructions that shade your lawn.
• Water your lawn deeply and infrequently before growth stops.
• Call the pros to apply a preventive fungicide.
• Shovel walkways and driveways around your lawn.
• Don’t pile shoveled snow on top of the snow in your lawn.