Dead Grass Spots in a Lawn

Even the healthiest of lawns are likely to run into problems occasionally. Dead areas in grass are often caused by a fungal infection. According to the North Dakota State University Extension, poorly growing grass that is not getting adequate water, fertilizer, light or air is more prone to disorders than vigorous turf.

Identification

Dollar spot is a fungal disease of grass caused by Sclerotinia homeocarpa, Lanzia sp. and Moellerodiscus sp. The disease is most prevalent during cool spring and fall temperatures of 60 to 80 degrees Fahrenheit.

Damage

The disease is characterized by the appearance of 1- to 2-inch round spots of dead grass in lawns. The dead areas are either straw-colored or have a bleached look. As disease progresses, the spots get larger and merge together to create wide, irregular patches. There are often fine, cobweb-like threads visible on the grass during early morning.

Management

Avoid overfertilizing soil and thatch buildup. Apply a top-dressing of compost to minimize disease symptoms and increase mowing height. Chemical control options include the use of iprodione, chlorothalonil, fenarimol and triadimefon.

References

• North Dakota State University Extension: Lawn Diseases
• University of California Extension: Dollar Spot
• Colorado State University Extension: Dollar Spot Disease of Turfgrass