LAWN DISEASE

Disease

Grasses
Affected/Season

Symptoms

Anthracnose

Any, but primarily bluegrass and centipedegrass.

Summer and fall.

 

Irregular-sized tan, brown, reddish-brown patches of grass ranging in size from several inches to several yards. Spots may also be present on grass blades. Can kill turfgrass if left untreated.

Brown Patch

Fescue, bluegrass, centipedegrass, ryegrass, St. Augustinegrass, bentgrass, and zoysiagrass.

Spring and fall.

Circular area of dead grass. The circle may be small or large. The outer portion may be a "smoky" color. The leaves can be easily pulled from the stem. Affected areas may have a sunken appearance. Does not usually cause permanent damage.

Dollar spot

Bentgrass, bermudagrass, ryegrass, bluegrass and fescue.

Late spring, summer and fall.

Small (silver dollar-sized) spots of tan/brown grass appear over the lawn. The spots may merge into large affected areas. Grass blades will have tan/brown areas on them. Does not usually cause permanent damage.

Fairy ring

All turfgrasses.

All year.

Dark green circle or semi-circle of grass. Area next to it may be a lighter-colored area of dying grass. Mushrooms may or may not be present. The entire affected area must be dug up and reseeded.  
Fusarium blight Bluegrass Prompted by hot, dry weather, color transitions from light green to brown to tan before dying.
Fusarium patch/snow mold

Cool-season grasses and zoysiagrass.

Fall, winter and spring.

Fusarium patch (or pink snow mold) usually occurs after snow melts but can be caused by cold, wet weather at other times. Starts as greenish yellow but turns a distinctive pink shade.

Gray color indicates another snow mold variety that matures under snow layers during colder winters. It also starts with a yellow tint but runs grayish white.

Leaf spot

All turfgrasses.

Spring, summer and fall.

There are leaf spot infections that attack warm- and cool-season grasses. Grass begins to appear gray, tan or brown. Upon closer examination, tan, red or purple spots are evident. Can severely thin or kill turfgrass.
Necrotic ring spot/summer patch

Bluegrass, bentgrass, bermudagrass and fescue.

Spring, summer and fall.

Round, sunken areas of reddish-tan grass that resembles a bull's eye. The very similar summer patch takes a more oval or irregular shape.

Powdery mildew

Bluegrass, bermudagrass and zoysiagrass.

 

 Common in shady areas, the infection resembles white dust. Blades eventually turn tan to brown. The damage can be permanent.
Pythium blight All turfgrasses Also called grease spot due to the brown slimy areas it produces. White patches may also appear. Can spread and kill grass quickly.

Red thread

 Fescue, bluegrass, ryegrass and bentgrass.

Red or faded patches, reddish or pink threads reach from leaf tips to adjoining leaves. Damage is usually not permanent.

 

Rust

Bluegrass, bermudagrass, St. Augustinegrass and ryegrass.

Summer and fall.  

Distinctive orange rust-like appearance. the spores will attach easily to tools and clothing. Not usually harmful.

Slime mold

All turfgrasses.

Summer and fall.

Patches of white/gray/black deposits on leaves. May appear powdery in early stages. Forms tiny balls as the infections matures. Slime molds will not cause permanent damage, but they can inhibit growth if the infestation is heavy. Remove with a rake, broom or by spraying with a garden hose.

Smut

Bluegrass and bentgrass.

Spring and fall.

Yellowing blades turn to black and begin to curl. The entire plant is affected and is likely to die.