Large Patch Disease (Brown Patch) in Oklahoma
You may have heard of “Brown patch,” “summer patch,” or “zoysia patch” – these are all actually Large Patch Disease, caused by the fungus Rhizoctonia solani.
This disease is active on warm season grasses (like Bermuda grass) in the spring and fall when temperatures are mild and wet conditions frequent. It occurs in grass that has been wet for an extended time, or in low areas where water stands. Large patch usually infects grass in the fall, although it’s not evident until spring. It will cease to be active when temperatures rise above 85º.
Symptoms are patches of brown grass that can measure up to 10 feet in diameter. You will see spots on the leaves, blackened or rotted stolons (runners) near the soil and sometimes thin brown or orange borders around the diseased area, showing that the disease is still active. Weeds will quickly encroach on the areas without turf.
Proper watering procedures can help prevent large patch. Water early in the morning, so that your grass doesn’t stay wet at night. Water thoroughly but infrequently. A good soak twice per week is much better than light watering every day (during normal conditions – drought conditions with high temperatures may require more frequent watering.) Correct areas where you have standing water or drainage issues.
Large patch can be spread easily. If you have large patch disease in your lawn, avoid walking through it to other parts of your lawn, and bag your clippings when mowing. Dogs, squirrels, and even running water can spread it.
Large patch is difficult for the homeowner to treat because the most effective remedies are available to lawn care professionals only. (If you’re a GreenGrass customer on our full program, we’ll treat large patch at no charge if it infects your lawn.)
If you see large patch disease in your lawn in the spring, make note of the areas that are affected – take pictures if you want. In the fall, you should have those areas treated with a fungicide. Large patch may not be evident in the fall, but the disease is still there. Treating it in the fall is much more effective than treating in the spring.
OSU Extension has a fabulous pdf with all kinds of info on Large Patch disease. Photo is courtesty of OSU Extension.