Common Turf Diseases

Please note that all the disease pictures on this page are examples taken from very short mowed turf. This makes for better pictures, but symptoms in a lawn situation where turf is taller, are often not so obvious.

Dollar Spot
The Dollar Spot is a common disease on Bluegrass. However, it can occur on other turf grasses. It is one of the diseases that can be discouraged by adequate fertilizer. It prefers warm days, and relatively cool nights. It often appears during abnormally warm fall weather. It is among the easiest of diseases to control. Different Bluegrass cultivars show a wide range of resistance to this disease.

Brown Patch
A Brown Patch is a troublesome disease which is very common on Tall Fescue turf. Brown Patch requires warm, humid days, and warm nights. During favorable conditions this disease is often present to some extent on almost every Tall Fescue lawn. Some cultivars of tall fescue have shown resistance, but none are immune. This disease rarely kills the turf, but can discolor it for extended periods. It can be managed with fungicides, but the disease pressure often outlasts the fungicide protection.

Leaf Spot
Leaf Spot is a common disease on Bluegrass. It prefers cool, wet weather. We see it mostly in the spring. It can discolor the lawn if many plants are infected. Leaf Spot is not tolerant of hot weather, so generally it is thought of as a temporary problem. When we have a long, cool and wet spring, this disease may eventually affect almost all Bluegrass lawns. It can be managed with fungicides, but generally is tolerated on a home lawn. Plants severely infected in the spring may weaken and die later in summer. This is called "melting out".

Summer Patch
The Summer Patch is a very serious disease on Bluegrass. It is caused by a soil borne fungus that colonizes the roots of the plant. It is a perennial problem on the lawns in which it is present. The infection of this disease initiates in late spring, but visible symptoms do not appear until late summer. Management of Summer Patch in a home lawn involves one of two options. You can convert the lawn to tall fescue, or you can help encourage recovery of the damaged turf in fall. Fungicide treatments for this disease are expensive, and results are often disappointing.

Powdery Mildew
Powdery Mildew is common during cool weather. It often appears in shady areas with poor air circulation. The white grass blades are easy to see, and this is an easy disease to diagnose. It generally does not permanently damage the turf, but it can be very persistent. It responds to many common fungicides.

Rust occurs on all types of grass, including Zoysia and Bluegrass, but is most common on Ryegrass. It often can be managed with proper fertilization. Rust frequently appears during wet periods of late spring and summer. During the hottest part of summer, this disease may show up in heavy shade areas. Fungicides are effective but are usually unnecessary. The spores of this disease are orange, and will stick to your shoes as you walk through the lawn. Orange shoes are a dead giveaway that this disease is present in the lawn.

Fairy Ring
A Fairy Ring may occur in any lawn. It is caused by a soil borne fungus. The classic symptom is the circular dark green narrow band in the lawn. This narrow band will turn brown as moisture stress develops over the summer. There are many variations of this disease. The bands may be circular, small arcs, or long and winding. Sometimes mushrooms will grow in the band. This condition may be unsightly, but rarely causes permanent damage. It is very difficult to eliminate.

Mushrooms (Toadstools)
Mushrooms and toadstools are fungi that often appear in home lawns. They may occur in conjunction with a Fairy Ring, but more often they occur during wet periods, where decaying organic matter is in the soil. Old tree stumps, buried lumber, or even a heavy thatch layer can provide the nutrients necessary to support these mushrooms. There is no chemical control for these invaders, and none is necessary. Just knock them over, or mow them down. If possible, you can attempt to remove the source of the organic matter, but often this is not practical.

Slime Mold
Slime Mold generates a lot of customer calls, but is harmless to the turf. It shows up as a grayish, dusty looking coating of the grass blade. It can be washed of the grass, or swept off with a broom. The mold usually disappears on its own after a short period.