While there are three common types of blight disease, only one presents a threat to Bermuda grass. Large-patch disease is easy to identify and is equally easy to treat. The disease is caused by a fungus that begins in the spring, survives the summer and is most active in the fall.
Large patch, as its name implies, develops as a light green patch on the lawn in the fall and can remain throughout the winter. In the spring, the patches may turn yellow and then brown. The centers of the circles often become sunken and may fill with weeds.
Conditions for Growth
Large patch is a fungal disease caused by Rhizoctonia solani that relies on the ideal conditions to germinate, usually begins with wet leaves or improperly aerated soil. Large patch develops at either the beginning or end of the turf's dormancy stage, in the spring and fall.
Because fertilizer has a profound effect on large patch disease, having a proper regimen is vital. The University of Arkansas Division of Agriculture Extension Service recommends a fast-release nitrogen-based fertilizer in early May to increase patch regrowth. Switch to a slow-release nitrogen fertilizer during the summer. Discontinue applications after Aug. 15.
According to the University of California, Davis, website, large patch disease can be controlled by a timely watering regimen. To help curtail the development of fungus, the grass should be watered in the early morning, allowing the leaves an opportunity to properly dry. Watering should also be done only on an as-needed basis to a depth of 4 to 6 inches.
For areas of grass where large patch is progressive and chronic, it may be necessary to treat with a fungicidal spray. According to the University of Arkansas, only commercial fungicidal sprays are available to treat the disease and they must be applied by a professional.