Summer Patch is a lawn disease that occurs during warm weather and attacks lawns all across the United States. A frequent bane of warmer climate regions, Summer Patch is caused by the lawn fungus Magnaporthe poae and is often associated with shallow root systems due to poor soil conditions.
Signs of Summer Patch include circular patches on lawns measuring from several inches to several feet in diameter. Grass leaves affected by this lawn disease turn from yellow to brown, starting at the tip and progressing to the base. This renders the patches a bronze-yellow to straw color. Grass roots also change colors to a moderate to dark brown. The patches from this lawn fungus often form a “frog-eye,” where less susceptible types of grass have survived inside the patch.
A Summer Patch infection can occur only if all of the following conditions are present: 1. Pathogen: Magnaporthe poae lawn fungus 2. Host: Multiple Bluegrass species or Fine Fescue 3. Environment: Warmer climates with temperatures ranging from 70°–80°F and compact soils with high moisture levels and poor drainage
Because you can't change your environment, the best way to control Summer Patch is to create conditions that will foster a healthy lawn. Not only will this make your yard unfavorable for Summer Patch growth, but it will also lower your risk of extensive damage should the lawn disease develop—plus you'll have the type of lawn you'll want to live on. For Summer Patch control and lawn fungus treatment, TruGreen® recommends the following cultural control tips: • Increase mowing height • Reduce soil compaction and thatch levels with core aeration • Lightly irrigate grass when temperatures are above 85°F • Improve the drainage of the soil • Fertilize with slow-release forms of nitrogen to continually feed the grass, but avoid rapid growth