How to Identify and Control Summer Patch

Almost every lawn has a few brown areas from time to time. Perhaps you mowed it too short or with a dull blade, or you forgot to put the kiddie pool away. No big deal. But if your lawn is slow-growing, has wilted turf, and is dotted with irregular, straw-colored patches and rings that get bigger throughout the summer, you may be dealing with a disease called summer patch.

Summer patch is a highly destructive fungus that kills grass by infecting and destroying its roots. Because it can survive in infected plant debris or perennial hosts, it can invade root tissue and remain undetected even in the winter. But when the hot weather hits, the fungus invades your lawn’s vascular system, destroying roots and essentially disrupting grass plants’ ability to take up water and nutrients.

Before you can take steps to effectively remedy the problem, however, you have to be sure that your lawn is suffering from summer patch. Here’s how to tell—and what to do about it.

Almost every lawn has a few brown areas from time to time. Perhaps you mowed it too short or with a dull blade, or you forgot to put the kiddie pool away. No big deal. But if your lawn is slow-growing, has wilted turf, and is dotted with irregular, straw-colored patches and rings that get bigger throughout the summer, you may be dealing with a disease called summer patch.

Summer patch is a highly destructive fungus that kills grass by infecting and destroying its roots. Because it can survive in infected plant debris or perennial hosts, it can invade root tissue and remain undetected even in the winter. But when the hot weather hits, the fungus invades your lawn’s vascular system, destroying roots and essentially disrupting grass plants’ ability to take up water and nutrients.

Before you can take steps to effectively remedy the problem, however, you have to be sure that your lawn is suffering from summer patch. Here’s how to tell—and what to do about it.

Summer patch usually appears between June and September during periods of high humidity and prolonged heat. Warm, moist soil and daytime temperatures that climb above 85 degrees F are also key factors. The disease can still be present during cooler weather conditions, but the symptoms won't be as noticeable.

Summer patch favors lawns that are stressed by heat and drought. It thrives in sunny spots, in areas where the soil is heavily compacted, in places with poor drainage, and on lawns that have been mowed too short.

• Annual bluegrass
• Kentucky bluegrass
• Fine fescues (creeping red and hard types)

Other types of lawn grass, such as tall fescue, perennial ryegrass, and zoysiagrass, tend to be resistant or immune to the disease.

Summer patch changes in appearance as the disease progresses. Look for any or all of these early warning signs and late-stage symptoms:

• Dark-green, wilted, irregular circles of grass up to 2” in diameter.
• Straw-colored patches, rings, and crescents that increase in size during summer.
• Enlarged patches, each with an outer edge that looks yellow or bronze.
• Grass blades that are dying back from the tip.

A lawn that is thick and well-cared for is less susceptible to diseases like summer patch. Keep yours in great shape by:

• Mowing at the correct height for your grass type.
• Watering deeply yet infrequently.
• Feeding regularly with Scotts® Turf Builder® Lawn Food, following label directions.
• Aerating and dethatching the lawn as needed.
• Overseeding regularly with Scotts® Turf Builder® Thick’R Lawn™ Sun & Shade or Scotts® Turf Builder® Thick’R Lawn™ Tall Fescue Mix (per label directions). Both contain turfgrass species that are resistant to summer patch, plus a fertilizer designed to make soil more acidic, which can reduce the severity of the disease.

If you determine your lawn is infected with summer patch, you will want to treat it right away. Because summer patch is such a destructive disease, you will need to apply a systemic control that’s both curative and preventive, like Scotts® DiseaseEX™ Lawn Fungicide. This product starts working in 24 hours and lasts up to 4 weeks, and should be applied at the first sign of disease. If you’ve had problems with summer patch in the past, help prevent it from coming back by applying when conditions are favorable for the disease but before it appears, typically in spring. Be sure to follow label directions.

Once summer patch is under control, repair the damaged areas quickly and easily by using an all-in-one patch and repair mix like Scotts® EZ Seed®. It contains high-performance grass seed, continuous release fertilizer, and super-absorbent growing material to help grow grass wherever you need it. Check the package for directions, and use this product during spring or fall for best results. Another option is to overseed your entire lawn with Scotts® Turf Builder® Thick’R Lawn™ Sun & Shade or Scotts® Turf Builder® Thick’R Lawn™ Tall Fescue Mix (depending on your lawn type) during early spring or fall to help restore your lawn to its original thickness.