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Lawn Disease Profile

What's at Play on Your Turf?

Turf diseases affect all types of grasses across the country and can leave your lawn in an unhealthy, unsightly state. Read below for the most common turfgrass diseases and how you can identify them.

Necrotic Ring (Ophiosphaerella korrae) is a lawn disease caused by a root-infecting fungus. It usually attacks sodded lawns in the northern United States and is often brought on by improper watering practices and high applications of water-soluble nitrogen. The disease takes the form of “frog-eye” patches – perfectly shaped rings of yellowed grass with healthy grass growing in the middle.


Dollar Spot (Sclerotinia homoeocarpa) is a common lawn disease that occurs during warm, moist weather. Dollar Spot fungi typically enter the lawn when it is wet, causing brown or straw-colored lesions to appear on the grass blades. These infected blades form circular, damaged patches the size of a silver dollar. As the disease spreads, it coalesces into larger patches, killing the grass.

Red Thread (Laetisaria fuciformis) is a fungal disease that favors cool, wet weather and lawns with low nitrogen levels. It is identifiable by pinkish red patches on the grass. Upon closer inspection, mycelium (fungus) in the form of tiny red “threads” may be evident on the affected grass blades.



Brown Patch (Rhizoctonia solani) is a hot weather fungal disease most damaging to tall fescue, perennial ryegrass, creeping bentgrass, and annual bluegrass. It appears as rough, circular patches between 1-10 feet in size. In the early morning dew, fine strands of grayish cobwebby mycelium may be present.



Leaf Blight (Ascochyta spp.) may take on similar symptoms to drought or fertilizer burn, although damage takes effect at a much quicker pace (often overnight). Fungal spores enter the grass during wet weather after the lawn is mowed, causing blades to die from the tip downwards. The disease can damage to lawns in the form of large, yellow patches.


Because turf problems are difficult to diagnose, rely on the knowledge and ability of your Weed Man to identify and treat various diseases. Once detected and corrected, Weed Man can help you adapt your cultural lawn practices to curtail future disease problems.

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