Lawn disease causes anywhere from unwanted dead patches to white fungi which can ruin a healthy landscape. There are several different kinds across the country. We have categorized the most common lawn diseases in southern California and offered preventative tips to keep your lawn healthy.

Brown Patch - Lawn Diseases

Brown Patch

Zoysia, Bentgrass, Ryegrass, Centipede, St. Augustine, Bluegrass and Fescue. Spring & fall. Large or small circles of dead grass, the perimeter of which may have a smoky color. Areas of lawn may appear sunken. Affected leaves can be plucked from the stems.

Favorable Conditions: 80-95 degrees with high humidity. This disease preys upon lawns with an overdose of nitrogen.

Prevention: reduce shade as much as possible, by clipping nearby branches and bushes. Reduce nitrogen intake, and increase water drainage. Remove any thatch which blocks air circulation. You may also use either Fungus Control for Lawns or NATRIA Disease Control by Bayer Advanced to combat the fungi.

Dollar Spot

Dollar spot

Bermuda grass, Ryegrass, Bentgrass, Bluegrass and Fescue. Late spring, summer & fall. Dollar spot creates what the name suggests – “spots” about 1-5 inches wide but can grow larger throughout your lawn. The leaves are brown and red at the tips and cobwebs can form in the mornings. Does not usually leave permanent damage.

Favorable Conditions: 60-80 degrees. Foggy conditions and excess moisture.

Prevention: ensure your lawn is sufficiently fertilized and watering is reduced. Increase breathing space, by removing any thatch in the lawn. You may also use either Fungus Control for Lawns or NATRIA Disease Control by Bayer Advanced to combat the fungi.

Leaf Spot

Leaf spot

Turfgrasses. Spring, summer & fall. Grass becomes tan, brown or gray with purple, tan or red spots. If not treated, kills or severely thins your lawn.

Favorable Conditions: 70-90 degrees for Bluegrases, Ryegrasses, and Fescues. 60-70 degrees for Bermuda grass, and Zoysiagrass. This disease favors high humidity, low-clipped grass and unbalanced amounts of nitrogen.

Prevention: reduce shade, improve soil aeration and water drainage. Re-evaluate your home or commercial property’s drainage system. See this article for more helpful tips on drainage. Monitor the amount of nitrogen you’re using for fertilizer. See this article for helpful tips on choosing the right Nitrogen fertilizer. Lastly, keep your lawn higher than normal, by reducing the amount of mowing.

Red Thread Lawn Disease

Red thread

Bluegrass, Fescue, Bentgrass & Ryegrass. Spring & fall. Look for faded or red areas with pink or reddish threads going from leaf tip to leaf tip. Although it won’t kill your plants, it can cause large areas of brown patches throughout your lawn. Doesn’t usually leave permanent damage.

Favorable Conditions: 60-75 degrees. Disease feeds on lawns deficient in nitrogen and during long periods of rainfall with high humidity.

Prevention: Irrigate based on the turf’s evapotranspiration needs and increasing nitrogen intake. You may also use Fungus Control for Lawns by Bayer Advanced.

Rust on Lawns


St. Augustine, Ryegrass, Bermuda grass & Bluegrass. Summer & fall. Appears orange and rusty. Spores spread easily by clinging to clothing and tools. Not usually harmful.

Favorable Conditions: 70-75 degrees. It feeds on lawns that are wet and deficient in nitrogen.

Prevention: maintain proper irrigation schedules based on soil conditions, rainfall and evapotranspiration. Find more information on rain sensors. Fertilize appropriately for each type of grass. You may also use either Fungus Control for Lawns or NATRIA Disease Control by Bayer Advanced.