The Ohio State University

Home LandscapeNotes A number of diseases are causing problems on lawns and sports fields. In the last week these diseases have been confirmed in various parted of the state and Midwest:

- Common Leaf Spot has been especially severe on several athletic fields of ryegrass. Photo 1 shows common leaf spot caused by Bipolaris and Drechslera fungi, on a perennial ryegrass from a soccer field in southern Ohio.

- Dollar Spot on susceptible ryegrass and Kentucky bluegrass lawns, especially a problem if there is slow growth

- Patch Diseases primarily on Kentucky bluegrass lawns and baseball fields that have excessive thatch or were sodded without proper site preparation resulting in a weak root system

- Rust on many ryegrass and ryegrass & Kentucky bluegrass lawns, especially a problem if there is slow growth such as from compacted soils, dry soils, low fertility, etc. Photo 2 shows rust spores erupting on surface of perennial ryegrass leaves. These dislodge and collect on shoes, mowers, pets, etc causing an orange or rusty color to the surfaces.

- Poa trivialis (rough bluegrass) is declining and going dormant with the high temperatures in the last several weeks. Since this grows in a patchy pattern in lawns if is often thought to be a disease. The key is to identify the host (turfgrass) as the first step in diagnosing a problem.

Be on the lookout for Gray Leaf Spot on perennial ryegrass! This DEADLY disease of perennial ryegrass has been confirmed in Kentucky. Some field tips to help identify this disease is that ONLY the perennial ryegrass is affected. Bluegrasses, bentgrasses and fine fescues are not affected and will be healthy and normal, while the perennial ryegrass declines. Also the general symptoms appear similar to drought stress BUT the soil will be moist to wet and not deficient in water. Under the microscope the spores are distinct from the other common leaf spots that are occurring now. The perennial ryegrass will often decline quickly. If this problem has occurred in the past do not delay in spraying fungicides and monitor closely for the disease. Planting resistant cultivars is important if perennial ryegrasses are seeded. To check for this disease send a sample to us for confirmation, or contact us if there are questions at: OSU Plant and Pest Clinic

Posted by Joe Rimelspach