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Brown patch is a lawn fungus that is common on cool-season grass such as; bluegrass, perennial rye, and especially tall fescue.

The fungus becomes active when nighttime low temperatures are above 65° to 70° when moisture and humidity is high. Other conditions that favor this fungus are; poorly drained soil, excessive thatch, compacted soil, poor fertilizer management, dull lawnmower blade, and evening irrigation.

Symptoms begin as scattered dead grass blades forming rough circles of a few inches up to a couple of feet. The circles initially develop a dark purplish color around the perimeter. As the circles get larger, they merge creating large patches fading from dark brown to tan.

Observing the grass blades around the perimeter of the brown area you will see, tan spots on the blade with dark brown or purplish margins. These spots enlarge until they merge covering the entire leaf

Another symptom looks like cobwebs and may be seen on a warm, dewy morning, these are the mycelium of the fungus and are a warning of what’s to come.

Brown patch rarely kills the grass it affects, but once the leaves turn brown, the turf is very susceptible to drought and heat damage.


Some cultural steps that reduce the risk of brown patch would be: Don’t water in the evening, water in the early morning. Don’t over-fertilize, especially in the early spring, fall applications are the best. Overseed or seed the area with, new improved, varieties that are ranked higher in resistance to brown patch and seed at the correct rate, seeding too heavy will lead to stress and fungus issues.

Keep your lawnmower blade sharp, brown patch always infects through the tip of the grass blade, especially a rough cut.

Although there are commercial fungicides available that are a little more effective, for homeowners, ferti-lome F-Stop granules is by far the most economical and effective. If ferti-lome F-Stop is applied as a preventer, either before infection or just as the first signs appear, a single application may be enough. All competing fungicides for homeowners require a minimum of two applications.

If someone would rather spray than apply a granule, ferti-lome Liquid Systemic Fungicide II is the best choice. This product always requires 2 applications and works better as a preventer than control. To learn more about treating brown patch in your yard, contact the experts at The Big Tool Box and Highlands Garden Center.