Brown Patch Disease: What It Is and How to Treat It

With Fall fast approaching, North Texas is experiencing more mild days and cooler nights. Unfortunately, this weather often exposes our lawns to more diseases. One of the most common diseases we see is  brown patch disease. It is called brown patch due to the circular or irregular patches of light brown to yellow grass it forms in shaded areas of lawns.

brown patch of st augustine grass

Rhizoctonia solani is the lawn fungus that causes this particular disease. We rarely see an infestation in the summertime because the long and hot days evaporate excess water. When the seasons change, the surplus water rests on the ground’s surface level for an extended period, creating an environment for the fungus to grow. It is for this reason that we find the fungus where the grass blades attach to the stolon.

structure of a grass plant

Do I Have a Problem?

The easiest way to determine if you are having a St. Augustine grass problem is to conduct a simple pull test. After removing some grass, ask a couple of questions.

  1. Did the blades release easily?
  2. Is the stolon or blades discolored? (Brown patch disease will not typically affect the color of the roots.)
  3. Is the base of the grass wet and spongy?

diseased grass

If you’ve answered yes to these questions, more than likely, you have a problem. Fortunately, this lawn fungus is relatively easy to treat.

Dealing with Brown Patch Disease
  1. Since it is a water mold disease, cut back on the amount and frequency of watering.
  2. Water in the morning hours, not at night. Doing this should help to lessen the amount of time the leaves remain wet. The goal is to water the root system, not the top level of the grass.
  3. For the Fall season, mow the lawn to about 2.5 inches in height. Doing this step will allow more air to circulate through the yard.
  4. Consider opening up the thatch* layer with a core aeration.
  5. If possible, trim trees and shrubs to allow more light to penetrate the area.
  6. Apply a fungicide to the area.

If you suspect that you have a lawn disease, please contact us at 888-233-5955. Our lawn care technicians will be happy to help you identify and develop a brown patch disease treatment plan.

Additional Resources
* Thatch is the buildup of dead grass from mowing and/or normal decay.
Brown Patch Disease – St Augustine Grass Video
Brown Patch – Wikipedia
Brown Patch Lawn Disease: Spring-Green Lawn Treatment for Grass Diseases