Get rid of brown patch fungus by immediately stopping irrigation, applying fungicide, and improving air circulation to eliminate moisture where the fungus thrives.
Brown patch has tell-tale signs. Look for bleached leaf blades with brown-bordered lesions and weird purplish edges. This fungus commonly affects tall fescue and ryegrass, spreading rapidly in hot, humid weather.
This guide covers five proven brown patch treatments from experts, plus prevention tips to restore your grass and keep it healthy.
1. Limit watering to reduce moisture
Brown patch thrives in moisture. Research from North Carolina State University shows that grass has to stay wet for 10 to 12 hours for the fungus to take hold and grow. So your first step is to cut off its water supply.
- Turn off irrigation to affected areas completely.
- Let infected zones dry out for 3 to 4 days minimum.
- Don’t water again until you see improvement
- Only water in the morning (before 10 am) to give any excess moisture time to evaporate.
Daniel Banting, vice president of Operations at Native Pest Management, emphasizes this critical first step: “The best treatment is to cut off your irrigation for a few days and apply a granular or liquid fungicide to contain and kill the fungus. Turning off the water takes away a main source that helps the fungus to survive.”
My tip: Standing water fuels the brown patch problem. Broken pipes, overwatering, or compacted soil can prevent water from draining. If you notice water pooling, especially after rain, check out our guide on “How to Get Rid of Standing Water in Your Yard” to get to the root of the problem.
2. Improve air circulation
Poor air circulation creates microclimates in your yard where brown patch can flourish. Quick fixes that work include:
- Prune overhanging branches from trees or dense shrubs. This increases sunlight and helps dry the area, especially in the shade where grass stays wet longest.
- Remove thatch if it’s more than half-inch thick. A thick thatch layer prevents water from soaking into soil, especially in compacted areas.
- Raise the mower deck by a half inch to 1 inch until the fungus has cleared up. When grass is fighting off brown patch fungus, it’s already weakened, and cutting it short adds extra stress.
- Sharpen mower blades to give a clean cut to promote healthier grass. Dull blades leave rough edges which hold moisture longer and fungus can easily grow in these damaged areas.
My tip: Many local hardware stores and mower repair shops will sharpen your blade for a small fee. I usually keep a backup set of blades ready if I need them. You can check out the following guide on “How to Change Your Lawn Mower’s Blade” if you haven’t had to do it before.
3. Apply fungicide treatment
The next step is to apply fungicide. You have options between liquid or granular. However, change treatment products if you have to regularly treat for brown patch, as the fungus can develop resistance pretty quickly.
“When properly applied, fungicide will help prevent the fungus from spreading throughout the lawn,” Banting says. “Depending on the size of the brown patch, if properly treated you can see results as soon as 2-4 weeks.”
Non-chemical DIY fungicides include:
- Beneficial bacteria: Products with Bacillus amyloliquefaciens strain D747 are OMRI-certified for organic production and highly effective against fungal diseases.
- Baking soda spray: Mix 1 tablespoon baking soda, 1 teaspoon vegetable oil, and 1 drop of dish soap per gallon of water; apply every 3-5 days.
- Neem oil: Purchase at any local garden center and mix according to label rates; typically requires weekly applications.
- Horticultural cornmeal: Apply 2 pounds per 100 square feet (or 20 pounds per 1,000 square feet); alternatively, make cornmeal tea by steeping 1 cup cornmeal in 5 gallons of water for 30-60 minutes.
Chemical fungicide treatment options:
- Strobilurin fungicides: Products with this active ingredient work best when applied at the first signs of infection.
- Curative treatments: Apply fungicides with azoxystrobin according to label directions every 7-14 days until you see improvement.
- Combination products: Mixtures containing azoxystrobin + propiconazole provide better control for severe infections.
For pet owners, Banting advises, “Granules can be highly effective but for homeowners with pets, utilizing a liquid fungicide is better. Once the fungicide dries, it’s safe for people and pets to walk on the grass.” For detailed fungicide options and application methods, check our guide on “How to Treat Lawn Fungus.”
4. Mow the right way
Improper mowing spreads brown patch spores like wildfire. Each pass of your mower can transfer the fungus from infected areas to healthy grass, expanding the problem rapidly. You’ll need to adjust your mowing techniques to prevent brown patch from taking over your entire lawn.
If you’re not sure of the ideal height for your lawn, check one of our many articles for your grass type, but always follow the one-third rule of mowing and adjust as needed.
5. Avoid overfertilizing
This might be the most important tip. Banting couldn’t be clearer: “Make sure that you, your landscapers, or pest company do not apply any fertilizer containing nitrogen. Nitrogen is like adding gasoline to the fire and will cause the brown patch to quickly spread.”
Instead, focus on strengthening your lawn with potassium-rich fertilizers (look for 15-0-30 formulas) and always test your soil before adding anything. If you’ve already over-fertilized, take action by watering deeply to flush excess nitrogen, applying activated charcoal, or introducing carbon-rich materials like sawdust to balance your soil.
Prevent Brown Patch Year-Round
Regular care keeps your grass healthy and is the best way to protect your lawn. Cut your grass at the right height, water only in the morning, and use fungicide treatments in early spring before nighttime temperatures hit 65 degrees. Remove excess thatch, use fertilizers carefully, and fix drainage problems.
Banting recommends: “In cold months where brown patch is prone, it’s best to reduce watering as much as possible. Many times you can’t prevent brown patch, and it appears in the same areas each year. One of the best things you can do is have a regular lawn service with a licensed pest company to provide regular iron and nutrients to keep the lawn healthy.”
When to call a professional
Brown patch can spread quickly and become too much for DIY methods.
“Treating brown patch DIY can be tricky if you do not know what you are doing,” Banting warns. “Applying the wrong products can not only cause the fungus to spread more but can also damage the grass.”
If you have a severe infection covering more than 30% of your lawn, multiple DIY treatments have failed or your lawn has multiple issues, it’s time to bring in professional help.
So, if DIY isn’t working or you’d rather leave it to the pros, Lawn Love can connect you with certified lawn care pros who specialize in disease control but also mow expertly, and at prices you can love.
Sources
Daniel Banting, Vice President of Operations, Native Pest Management
Kansas State University Extension – Brown Patch Disease Management
North Carolina State University TurfFiles – Brown Patch in Turf
University of Florida IFAS Extension – Turfgrass Disease Management
Purdue University Extension – Brown Patch Control in Lawns
Main Image: A lawn infected with brown patch: singjai | Adobe Stock
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