I woke up the other morning a thought that my lawn was covered in frost. When I arrived home from work that afternoon the lawn was still covered in white. The temperature was 58 degrees at the time and I thought something’s wrong. Upon closer inspection I realized that it was a grey/white mold that was covering my lawn. This mold is commonly called “snow mold”. It forms in weather conditions like what we’ve had this last year in Minnesota; wet cold weather for long periods of time. After a very wet fall, followed by a typical snowy winter and a rainy spring the conditions were ripe for snow mold. It can appear in two forms. Gray snow mold causes irregular dead , bleached patches in your lawn. The grey mold is clearly visible on your grass like the picture above. The other form is pink snow mold which produces circular, light brown patches that are sometimes blotched with pink fungus like the picture below.
If left without treatment both forms can cause the grass in the affected area to die. Treatment involves lightly raking the area and then using a fungicide. Raking removes the mold and allows the grass to breath. Be careful not to pull out your grass with the mold. Your lawn is at a fragile stage right now and heavy raking will do some real damage. Fungicide kills the mold and helps prevent the mold from returning. Bonide brands “Infuse” is a good choice of fungicide treatment.
You can also help prevent this from happening by taking some measures in the fall. Do not use a fertilizer that is high in nitrogen in the late fall. Also you can aerate your lawn to improve drainage. DO NOT aerate your lawn right now. Aerating your lawn too early will do more damage than if you left the mold and did nothing else. Aerating too early tears up your grass and rips out the root base of the lawn. You need to wait until your lawn dries out before doing any aeration. See my Spring Lawn Care blog for more info on lawn aeration.
- What Is Thatch? (lawnpros.biz)