Large brown spots on a lawn can be caused by a fungus commonly known as brown patch disease, or large patch. All types of lawn grasses grown in Texas, such as St. Augustine, can be affected by brown patch. Humid conditions, mild days (70° to 90° F) and cool nights are ideal for development of brown patch disease.
- Varies greatly with the type of grass and soil conditions
- Thinned patches of light brown grass that are roughly circular in shape
- Diameters of patches range from a few inches to several feet
- Irregular, tan leaf spots (burnt cigarette appearance) with dark-brown borders on grass blades near the soil surface
Control and Management:
- Water lawn only as needed and to a depth of 4-6 inches. Water early in the day to allow the grass to dry quickly. Use a simple moisture meter to determine moisture content of soil.
- Avoid over fertilization in spring and fall.
- Improve turf grass root system with good drainage and aeration.
- Avoid spreading the disease to other areas. Remove grass clippings if the weather is warm and moist to prevent spread to other areas during mowing. Prevent thatch build up.
- Fungicides (See the section Chemical Controls for Turfgrass Diseases) are most effective when used on a preventive basis.