Ag Line: Take-All Root Rot
Farm & Home
By Wade Parker
County Extension Coordinator

Has anyone noticed yellow centipede and St. Augustine yards? Each year, I get several calls concerning yellow yards. Most of the time yellowing of a lawn is usually a sign that Magnesium levels are low. A single treatment of Mg thru a pull behind sprayer usually does the trick. However, this year we had a wet spring. The wet spring has caused take-all root rot to rise to new levels. The cool weather we have been experiencing has also exasperated take-all root rot.

This fungal disease can affect all warm season grasses, but it is particularly problematic on centipede, St. Augustine and Bermuda lawns. However, I am mainly seeing it now on centipede and St. Augustine. Affected lawns may show round or irregular dead or dying patches. The grass may yellow or wilt even though the soil is moist.

The organism that causes Take All, rots the lawn's roots, leaving them black. The disease also attacks the above ground runners (stolons) - especially at the nodes. Stolons may be brown or black at the nodes or have dead patches on them. One of the best ways to identify this disease is to look for the fungal growth (black, thread-like structures called hyphae) growing on the outside of the stems. These should be more common on the underside of older stolons. However, it takes a microscope or a good hand lens to see these hyphae. Our office has these microscopes, so feel free to bring in a sample.

This disease infects lawns in the fall and early spring. Unfortunately, by the time we see the symptoms of this disease, much damage is already done.Since this disease destroys roots, lawns may be slow to recover. Affected lawns will also be more susceptible to other stresses - herbicides, drought, etc. Give special care to affected areas until they recover.

Much of the damage of this disease is probably behind us now. A fungicide may be helpful in some cases - especially if someone plugs in or sods some more turf into these areas. The biggest thing we can do now is to implement sound cultural practices that will slow the disease. Make sure the soil pH is not too high (ie above 6.5), water deeply and infrequently, do not allow the soil to remain wet and remove thatch if the thatch layer is thicker than one-half inch. Expect the disease to slow growth with warmer weather. Core aeration will be helpful.

A fungicide application might help some now, but fungicides are best applied in the fall to prevent this disease. Treat in September and again in October to prevent this problem. For now, the best control is improve cultural practices to prevent the disease and to increase the vigor and to hasten the recovery of the turf.