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Blanket of Snow


By Heather Vigil - March 1, 2019

Blankets of Snow
Photo courtesy of CSU.


After suffering throughtwo years of receiving roughly half the average annual precipitation per year, February has been one of the wettest and coldest we have experienced in many years. 
As arborists in Denver, we rarely complain about snow, unless it occurs in late spring or the early fall.  Prior to the February snows we were routinely on client properties completing winter watering treatments with Yuccah extract, to prevent winter desiccation and/or drought stress in plant material.
The snows of the previous 4-6 weeks have also been relatively wet snows for this time of year, with very high moisture content.  The slow continuous melting of the snow has resulted in a slow, and consistent penetrating moisture for our landscapes.  This is the best delivery of moisture landscapes can receive, as it reduces the amount of run off and evaporation.
The snow cover, even if only temporary, also insulates and protects landscapes from the cold temperatures in a storms wake.  The insulation of the snow also protects from erratic temperature swings often drying Chinook winds, as well as increasing the humidity-which evergreens and broadleaf evergreens enjoy.
However, there are some disadvantages for the landscape with the bounty of snow storms we have been experiencing.  Snow can often hide, even if temporarily, defects or damage that has occurred to our landscape plants over the winter months.  Examples are voles and spider mites.  Voles are very active during the winter, and with the means they create their tunneling systems to and from wherever they are traveling, are well hidden under snows, in portions of your yard that aren’t melting as quickly.  This allows them to tunnel to their hearts content; all the while girdling the stems and roots of desirable plants, unbeknownst to you.  The damage will present itself in the early spring as the plants begin to move moisture and nutrients.  There will be visible dieback, sporadically throughout the plant.
Rabbit activity is also common during winter, particularly with snow cover.  When there is snow coverage rabbits have less accessibility to their preferred food sources.  While it is not as common for rabbits to feed on landscape plants, during lean years they will.
Here is a link about vole activity:
https://extension.colostate.edu/topic-areas/natural-resources/managing-voles-in-colorado-6-507/
A disease that can affect lawns in Denver landscapes during winter months is called Gray Snow Mold.  Most commonly the Gray Snow Mold is seen in our area.  Gray snow mold occurs when we have snow coverage for a minimum of 40 days consecutively.  Gray snow has the appearance of a moldy, stringy, and cottony mass that can blanket the grass underneath snow cover.  Snow mold is caused by a lawn fungus, however it typically should not cause alarm once the snow has melted. It is a relatively benign fungus that rarely results in Kentucky bluegrass damage or plant death.  Kentucky blue grass and fine fescues has a hardy resistance to the fungus, while rye grass and tall fescue grass are more likely to be harmed.
There are ways to aid in the prevention of snow mold.  Do not leave large layers of un-mulched leaves on turfgrass, as it can imitate a layer of snow; increasing the risk of snow mold occurring.
The snow mold will be visible once the snow has melted.  If a light, patchy layer of snow exists with snow mold being visible, raking the area to remove the matted areas, allow exposure to the air and sunlight, will greatly aid the turfgrass in recovery.
If the lawn did sustain death due to gray snow mold, over-seeding is a good choice in the spring.
Here is some more information on gray snow mold:
http://planttalk.colostate.edu/topics/insects-diseases/1400-15-snow-mold-lawns-colorado/