Brown Patch Lawn Disease
The beauty of a lawn can be quickly destroyed by brown patch (Rhizoctonia species), also called large patch, a serious fungal disease that can affect all turf grass species. It can develop rapidly when temperatures are warm (75 to 90 °F) and humid, especially on cool-season grasses (fescue, ryegrass, and bluegrass). It can also occur on these grasses during warmer periods of the winter months. Warm-season grasses (St. Augustinegrass, zoysiagrass, bermudagrass and centipedegrass) most commonly are affected by brown patch during the early spring and late fall.
GRASSES COMMONLY AFFECTED
All types of lawn grasses can be affected by brown patch. There are no turfgrass species entirely resistant to brown patch currently available. Brown patch is the most common and important disease of tall fescue. In most cases affected areas are able to recover, but tall fescue lawns less than a year old can be completely killed.
Symptoms of brown patch may vary greatly with the type of grass and soil conditions.
- The disease usually causes thinned patches of light brown grass that are roughly circular in shape.
- These areas range in diameter from a few inches to several feet. Often the center of the patch will recover, resulting in a doughnut-shaped pattern.
- When disease conditions are favorable, large areas of the lawn may be uniformly thinned and eventually killed with no circular patch being evident. This type of pattern is commonly seen on infected St. Augustinegrass grown in shady, moist locations.
- Close inspection of cool-season grass blades reveals small, irregular, tan leaf spots with dark-brown borders.
- Infected warm-season grasses rarely have leaf spots but instead have rotted leaf sheaths near the soil surface.
PREVENTION AND TREATMENT
- The best way to prevent brown patch in the home lawn is by following good lawn care practices. This is much easier and less expensive than the use of fungicides and can be very effective.
- Avoid high rates of nitrogen fertilizer on cool season grasses in the late spring and summer. Avoid high nitrogen rates on warm season grasses in mid to late fall. The brown patch fungus readily attacks the lush growth of grass which nitrogen promotes. Your Fairway Lawns technician will apply the proper amounts of fertilizer.
- Irrigate grass only when needed and to a depth of 4 to 6 inches. The best time to water is early in the morning. This disease can spread fast when free moisture is present.
- Avoid spreading the disease to other areas. Remove clippings if the weather is warm and moist to prevent spread to other areas during mowing.
- Keep lawns mowed on a regular basis to the proper height for the grass species you are growing. Prevent excessive thatch buildup.
- Provide good drainage for both surface and subsurface areas. Fungicides shouldn’t be relied upon entirely for controlling brown patch but they are sometimes necessary to control brown patch infestations. Your Fairway Lawns technician can determine whether or not a fungicide application is necessary for your lawn.