Brown Patch Disease: Lawn Care and Control Tips

Brown patch can quickly turn your beautiful green yard into uneven, tired‑looking spots, and it’s upsetting to watch the damage grow day by day. This lawn problem typically occurs during hot and sticky weather, especially when watering isn’t quite proper. Here we’ll talk about what brown patch really is, why it happens, and how you can help your lawn bounce back with easy, caring steps.

What Is Brown Patch Disease?

Brown patch is a common leaf disease of grass caused by the fungus Rhizoctonia solani. This fungus lives in soil and grass debris, and when conditions turn hot and humid, especially when nights stay above about 20 °C (68 °F) and leaves remain wet, it becomes active. It attacks grass leaves, causing brown, often circular, dead spots that can quickly spread and ruin your lawn’s look.

Here’s a list of grass types that brown patch tends to attack the most:

1. Perennial ryegrass (Lolium perenne)
2. Tall fescue (Festuca arundinacea)
3. Creeping bentgrass (Agrostis spp.), including colonial and annual bluegrass
4. Kentucky bluegrass (Poa pratensis) and fine fescues — these are less often affected and usually less damaged when they do get brown patch

Causes of Brown Patch

Brown patch happens when several factors come together to create the right environment for the fungus. Research shows it’s not just one thing but a mix of weather, soil, and lawn habits that set the stage:

• Hot, humid nights: When nighttime temperatures stay above about 60–65°F and the air feels sticky, the fungus becomes active and starts to spread.
• Too much nitrogen fertilizer: Heavy feeding in summer makes the grass produce soft new growth that’s easier for the fungus to attack.
• Late‑evening watering: If lawns are watered at night, the blades stay wet for hours, which gives the fungus more time to infect them.
• Poor air flow and drainage: Thick thatch, tightly packed soil, or crowded lawns hold moisture and keep grass damp, which the fungus loves.

Image showing brown patch development: early lawn symptoms (A, B), the fungus in culture (C) and under a microscope (D), and turf response under different conditions (E–H).

Symptoms on Lawns

There are 5 main symptoms to watch for:

1. Round brown spots. These start small but quickly grow, blending into bigger, damaged areas.
2. Dark smoke rings. In the morning dew, you might spot a faint gray or purple ring around the spots.
3. Damaged leaf blades. Look closely, and you’ll see tan or light brown streaks edged in darker lines.
4. Webby fungus. On humid, wet mornings, you may notice a thin, cotton‑like layer on the grass.
5. Hollow centers. Severe patches can thin out in the middle, leaving a donut‑shaped ring of damage.

Lawn Care and Control Tips

Tip Area	What to Do
Watering	Water early in the morning 2–3 times a week, deep enough to reach roots. Avoid nightly watering, and try to keep blades dry before dark.
Fertilization	Apply nitrogen carefully in spring and fall, and go easy in summer. Use slow‑release fertilizers so growth is steady, not sudden.
Fungicides	Start with preventive sprays in late spring if your lawn gets brown patch often. For outbreaks, use curative fungicides and follow label instructions for repeat treatments.
Aeration & Mowing	Aerate compacted soil each year, dethatch if needed, and mow at the right height (not too short) to improve airflow and help grass stay strong.
Lawn Care Habits	Clear leaves, don’t let clippings pile up, and keep tools clean so you don’t spread fungus from one area to another.

Conclusion

In the end, brown patch doesn’t have to be the end of your lawn’s beauty, and you don’t have to figure it all out alone. The Planteyes app works wonderfully for spotting lawn diseases like brown patch early, and it goes a step further: you can chat right inside the app, just like talking with a lawn care expert, to get tailored solutions for your yard. Download Planteyes today and give your lawn the support it deserves.

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