Extension Educator, Horticulture
Stockpiled snow has finally surrendered to salt and sun. Unfortunately its retreating has exposed my shaggy dog of a lawn. If only I could send it out for a wash and a blow-dry. Long periods of snow cover can cause a myriad of lawn woes.
Many lawns weren't picture perfect going into winter. Snow is nature's air brush; it masked the flaws but didn't really improve the lawn's condition. As snows recede lawns may show damage particularly from voles and from snow mold fungal diseases.
Voles will make runways under the snow in lawns as they feed on grass blades and roots. Voles are well protected under the snow from hawk and owl predators. A couple species of voles can inhabit your yard. Voles may have brown to reddish-brown fur and range from 4 to 7 inches long. They have stockier bodies and shorter tails than mice. Damage is frequently mistaken as mole damage, but moles are not active during winter. Vole damage appears as surface runways or winding trails of damaged grass. Indirect vole damage occurs as my dog tries to dig out the offending voles.
Once spring arrives grass will usually grow into and fill-in the surface runways; however, severe damage may require some overseeding of lawn grass in April. Voles love tall vegetation; therefore, prevent damage from occurring by continuing to mow lawns to a height of about 2 inches until grass is completely dormant in fall. Also clean up any excessive vegetation near lawns, as this provides cover for voles.
Vole damage in lawns may be cosmetic; however, voles can cause a great deal of damage in flower gardens by eating the roots of perennials. It's difficult to control them in large flower beds and trapping may be needed. I'm leaning more and more to clearing garden beds in fall to help the predators find the voles before the snow arrives. Check out this website for more information on voles and many other wildlife. http://web.extension.illinois.edu/wildlife
Snow mold damage can also be very visible on lawns as snows recede in spring especially if we get a prolonged snow cover on unfrozen soil. Both gray (Typhula blight) and pink snow mold (Fusarium patch or Microdochium patch) may occur. During the wet, cold weather of early spring, snow mold may be highly visible as matted, crusty looking areas. Gray snow mold appears in roughly circular yellow to whitish-gray patches. As conditions dry out, snow mold will gradually go dormant. Often just leaves are affected and new grass blades grow as weather warms. Severely infected areas may remain in the form of weak or even dead turf. To repair damage, rake matted grass and re-seed or resod as necessary in April.
Snow mold severity may vary from year to year, but certain turf areas seem to be frequently affected. Conditions which may contribute to snow mold include tall matted-down grass, excessive use of fast-release (water soluble) nitrogen fertilizer in early to mid fall, excessive thatch, excessive shade, poor drainage, and excessive debris (such as leaves or straw) on the turf. Areas receiving drifting snow or piles of deposited snow are also prone to snow mold.
Ways to avoid snow mold from becoming a severe problem include: follow sound fertilization programs; use fertilizers containing slow-release or controlled-release nitrogen; and manage thatch via aerification or removal with vertical mowing (dethatching). Surface drainage should be adequate. Improve air circulation by pruning or removing dense vegetation bordering problem lawn areas. Damage from voles and snow mold can be minimized by keeping lawns mowed until grass is completely dormant in fall.
Check out these great University of Illinois Extension websites for more information on lawn care. Lawn Talk http://www.urbanext.uiuc.edu/lawntalk/ Frequently Asked Lawn Questions http://urbanext.illinois.edu/lawnfaqs/
And take the Lawn Challenge http://urbanext.illinois.edu/lawnchallenge/