Published on Wednesday, 30 November -0001 00:00
By Janelle Daberkow, U of M Extension
Now that the snow has melted, we are seeing the damage that the long winter, and associated issues have had on our lawns. Depending on where you live, and how you care for your lawn, you may be seeing some new problems, or you may be seeing a reoccurring condition. Here are some tips to keep in mind for lawn care this spring.
Voles: If you are seeing small surface tunnels through areas of the lawn accompanied by piles of dead grass, or small dish-like depressions filled with grass, you are probably seeing vole damage. Voles are small mouse-like rodents that feed under the snow throughout the winter. Damage to the lawn can be repaired by raking the area well to remove the dead grass. While lawn damage is most visible in the spring, it is rarely permanent. Normally, the grass has been eaten at the soil level, and if the roots are undamaged, they will send up new growth. If after the surrounding grass is growing and there is no growth in these areas, loosen up the soil and reseed with a lawn seed mixture.
To discourage voles and prevent damage to the lawn next winter, keep the lawn mowed regularly until freezing and remove excessive thatch. You might consider lowering the lawnmower slightly, but do not mow the grass shorter than two inches or the crowns of the lawn grasses will be subject to winter injury. Eliminate any weeds, wild grasses or litter from around the lawn so it does not provide food and cover for the voles. If active runways are present in the lawn, trapping may be effective. Mouse traps baited with a mixture of peanut butter and rolled oats should be placed adjacent to the runways or in areas where voles are active. There are some poison baits labeled for outdoor use against voles and readily available mouse and rat baits can be effective. In late fall or early winter, create a bait station by placing about a tablespoon of dry pelleted bait in a soup can, PVC pipe, or other bait station. Place the bait stations in areas that were damaged by voles this winter and near young trees or shrubs. Check the bait stations several times a week before snowfall and replace any bait that has been consumed, and then keep them in place throughout the winter under the snow. Be sure to read and follow all directions and precautions on the label of the poison you purchase to use in the bait stations. Bait stations should be used with extreme caution because they may pose a threat to children and pets. They should be removed in the spring as soon as the snow melts.
Snow Mold: A second problem seen in the lawn this spring would be snow mold fungus. This is seen as circular straw-colored patches in the lawn. Snow mold does not occur every year, but it is common during years when an early, deep snow cover prevents the ground from freezing, much like we saw over the last winter. This fungus becomes active at temperatures near freezing and develops under a blanket of snow or unfrozen ground. Snow mold can affect lawns after the snow melts, as long as conditions are cool and wet. As temperatures rise and lawns dry, the fungus becomes inactive. There really is no need for chemical control unless there is an area of the lawn where snow mold appears every year. In severe cases, a preventative application of thiophanate methyl (Cleary's 3336 or Bonomyl) in October or early November may be helpful. There are two types of snow mold, pink and gray. Each is caused by a different fungus. In either, the snow mold appears within the lawn as a circular, straw-colored patch of grass matted down and is often covered by a white, pink or gray fungal growth. Occasionally mushrooms will be seen appearing from the affected turf. Damage is rarely serious, infected areas are just slower to green up. Gently rake affected areas of the lawn to promote drying and prevent fungal growth. If spots fail to green up, rake them out well and reseed. To minimize damage in future years, avoid excessive applications of nitrogen in the fall. Continue to mow the lawn at the recommended height until it is no longer actively growing. The taller the grass, the more likely it will mat and encourage snow mold. Again, do not cut the grass shorter than two inches. Grass that is too short will be subject to winter injury in the event of a cold, minimal snow-cover winter. Rake up leaves in the fall, as a heavy layer of leaves causes cool, wet environment for snow mold in the spring. As the snow begins to melt, break up and spread out large snow piles. Areas where snow is trapped become areas of concern for snow mold.
Raking: No matter how beautiful the weather, keep off the grass until the soil feels fairly firm underfoot and you no longer leave footprints when you walk across the lawn. If it's still soggy wet, you will compress the soil wherever you step which will add to compaction and promotes poor root growth and poor water drainage. This is especially important if you are going to use your lawn tractor or other heavy equipment to clean your yard. In addition, it is very easy to pull the grass out by the roots when the grass is wet. The actual time to start raking the lawn is dependent on moisture levels in the soil, soil type, amount of rainfall and drainage of the lawn. When the lawn is ready to rake, use a lightweight lawn rake. The lighter rake removes dead grass and weeds as well as allows air to reach the crowns of the grass plants without harming the roots.