So why all the problems with snow mold this spring? The answer lies in my opinion with the weather last November. Even though you possibly did everything right, weather conditions set up for the perfect storm, especially if your lawn is clay soil based or you haven’t core aerated in a few years. The lawn was still growing when the early snows hit last year….followed by a long winter of snow cover. The lawn is the host and the disease we call snow mold was present waiting for conditions to be ripe. You see even though we as people are dealing in winter with frigid winds and cold….under the snow which serves as insulation the turf is in a wet humid dark environment with temperatures around or just above freezing….ideal conditions for snow mold. I went back to look and the first 10 to 15 days of November we had some days in the 50’s and 60’s. Mid November on we had wintery wet snow and the blanket caused a problem. Especially if you are a person who puts their lawn mower away based on a calendar as opposed to putting it away with a good short cut when it stops growing. The turf continued to grow and could not photosynthesize due to dark conditions. At that point the dormant snow mold had the “perfect storm” conditions to develop under the snow and persist until the snow finally cleared last week. In most cases a leaf raking with some sunlight and air will allow the lawn to recover. In serious cases where there is crown damage their may be dead grass where turf areas need to be re-seeded. It is a good reminder too in my opinion that if you have a clay based soil lawn that fall aeration is a good idea. It is also interesting to note that the fungus under the cover of snow produces a gas that can be toxic to turf leaves.
The good news is in most cases a light raking with a leaf rake allowing light and air into the turf will eventual fix the problem and the lawn will grow out of it. Feeding and some over seeding when the soil get’s warm enough in April will also make the difference in recovery.