Summer patch: ID and recovery

Summer patch is the most damaging turfgrass disease in the mid-Atlantic and northeastern United States. It kills Kentucky bluegrass and fine fescue lawns in a pattern that looks dramatic in August but began months earlier, when the pathogen infected roots in spring. By the time you see the damage,.

Summer patch is the most damaging turfgrass disease in the mid-Atlantic and northeastern United States. It kills Kentucky bluegrass and fine fescue lawns in a pattern that looks dramatic in August but began months earlier, when the pathogen infected roots in spring. By the time you see the damage, the infection window is long closed.

Pathogen and host range

Summer patch is caused by Magnaporthiopsis poae (formerly Magnaporthe poae). Per Penn State Center for Turfgrass Science, the disease primarily affects:

• Kentucky bluegrass (Poa pratensis) — most severely
• Annual bluegrass (Poa annua) — often the initial host in the patch center
• Fine fescue (Festuca spp.) — affected but less severely

Tall fescue, bermuda grass, and perennial ryegrass are not significantly affected.