· by Michael Blair, Nashville's Weed and Feed
Warm nights and high humidity are what brown patch needs, and a Middle Tennessee July supplies both. On fescue it is the most common disease by a wide margin.
What does brown patch look like?
Roughly circular patches from a few inches to several feet, often with a darker smoke-colored ring visible in early morning dew. Individual blades show tan lesions with a dark border.
It spreads while the surrounding lawn stays green, which distinguishes it from dormancy.
What causes brown patch in fescue?
Leaf wetness overnight, high nitrogen going into summer, poor air movement, and thatch. Evening watering is the most controllable of those and the most common mistake.
Watering early so the blades dry as the day warms substantially reduces pressure.
- Water early morning, never evening
- No heavy nitrogen going into summer
- Raise mowing height and keep blades sharp
- Improve air movement where you can
- Fungicide is preventive rather than curative
Cultural control first
Correct watering timing, sensible mowing height, a sharp blade and avoiding summer nitrogen do most of the work. Torn blade tips from a dull mower are an entry point.
A lawn managed this way still gets brown patch in a bad year and gets it less and recovers faster.
Fungicides
They are preventive rather than curative — applied before or at the earliest signs, on a repeat interval through the pressure period.
For most home lawns the cultural approach plus accepting some summer damage is the reasonable position, since fescue recovers with autumn overseeding.
FAQ
Brown Patch and Middle Tennessee Humidity — questions
How do I know if it is brown patch or drought?
Brown patch appears as roughly circular patches spreading while the surrounding lawn stays green, often with a darker ring in morning dew. Drought and dormancy are uniform across the lawn rather than patchy. Anything patchy in an otherwise green lawn is not dormancy.
Does watering at night cause lawn disease?
It contributes substantially. Brown patch needs leaf wetness through warm nights, and evening watering supplies exactly that. Watering early enough that blades dry as the day warms is one of the most effective and cheapest things you can change in a Middle Tennessee lawn.
Should I use a fungicide on my lawn?
For most home lawns, cultural control plus accepting some summer damage is reasonable — fescue recovers with autumn overseeding. Fungicides are preventive rather than curative and need repeat applications through the pressure period, which is a real ongoing cost.
How do you treat brown patch in a lawn?
Mostly by changing the conditions: water early so the blades dry as the day warms, skip heavy summer nitrogen, mow at a sensible height with a sharp blade and improve air movement. Fungicides are preventive, applied at the first signs and repeated through the pressure period. For most home lawns, fall overseeding repairs what summer took.