Lawn Disease

Most Common Lawn Diseases in Minnesota and Wisconsin

Snow Mold – Snow mold disease infects grass during the late fall, through the winter and into the early spring. Snow mold creates patches of brown grass, usually matted over and crusty as it dries out. Because snow mold infects under the snow layer, a fungicide needs to be applied before snowfall in the fall. Snow mold treatment is a different treatment not included in the normal Disease Control Program. bioLawn offers a separate Snow Mold Preventative application for this disease.

Summer Patch – Summer Patch infects the lawn in May and June. Summer Patch creates circular rings of dead grass with green grass in the middle. The visual evidence of an infection shows up in July and August after the disease has already infected. Typically, a lawn is diagnosed with Summer Patch in late summer and treatments begin the next year to prevent future infections.

Red Thread – Red Thread can infect the lawn anytime there is excess moisture, usually in cooler weather. Red thread creates pink strings/strands in the lawn, that then bleaches the leaf blade. Red Thread causes visual disturbance but doesn’t kill the grass. Because of this, red thread is often not treated. Because moisture can occur at any time treating red thread requires all 5 applications of the Disease Control Program.

Dollar Spot – Dollar spot infects the grass when nighttime temperatures are above 65 degrees and there is plenty of moisture. Dollar spot produces small (tennis ball sized) brown spots in the lawn. This disease does not kill the grass. This disease is often not treated, but when a client wants to control it applications are done June – September.

Ascophyta – Ascophyta causes a rapid bleaching of the leaf tissue. It does not form specific shapes and it covers a sizable portion of the lawn. It most often infects during hot weather but has shown up in cooler weather. Ascophyta is a secondary infector and usually infection occurs after mowing that stresses the grass. The Disease Control Program is marginally effective against this disease but can help.

Fairy Ring – Fairy Ring is a soil borne disease in the soil. Fairy ring does not infect the grass. Rather it decomposes organic matter in the soil and releases nitrogen. This nitrogen causes the grass to form a dark green circle. When excess moisture is present, the fungi will produce mushrooms in the lawn. These mushrooms do not harm the grass but do create a visual disruption in the soil. The disease control program can help, but since there are many types of Fairy Ring fungi, applications are needed throughout the year. To get the best results, applications to control Fairy Ring should be watered into the soil.

Rust – Rust typically infects in the summer and fall under high humidity conditions. Rust produces an orange look to the lawn that will get all over shoes. Applications of the Disease Control Program in July – September can prevent Rust.