Typical symptoms include thinned lawns with yellow St. Augustine grass, brown and dying areas and in some cases bare spots. Also, the lawn doesn’t appear to respond as well to fertilizer applications.
It should be noted that there were not a lot of good St. Augustine grass lawns out there this spring to begin with.
Reasons for these damaged St. Augustine grass lawns include extremely hot, dry weather during the last few months followed by cool, cloudy weather last week; and take-all root rot, a fungus that is rampant in our area.
While “take-all” is definitely out there and a contributing factor, I believe that the real problem is stress factors in the lawns that weakened the grass and allowed the take-all root rot to become active in the lawn early on in the winter and spring. Individuals who did not water their lawns during this period created a stressed turf grass plant. The stressed lawns inhibit the plants from producing and storing the necessary carbohydrates for growth.
Then the above-average rainfall kept the soils saturated and reduced the amount of available soil oxygen. This would affect the St. Augustine grass plants’ ability to develop new root growth.
Listed below are some recommendations for treating these St Augustine grass lawns.
• First, apply only light rates of nitrogen fertilizer. Overapplying nitrogen fertilizer will only make the problem worse in most cases. Most of these damaged lawns have a very limited root system at this time and forcing excess top growth with too much nitrogen fertilizer will only make the problem worse.
• Apply iron for the correction of yellowing (chlorosis) in the lawn.
• Avoid the application of herbicides, both pre-emergent and post-emergent herbicides, to these lawns. Application of herbicides to stressed St. Augustine grass could be the icing on the cake that totally kills the grass.
• Aerification to correct soil compaction problems should help the grass recover from the damage.
Treatment for the take-all root rot is going to be difficult at best. There are some fungicides that are labeled for the control of “take-all.” However, these products are not readily available for most homeowners and they are very expensive.
Also, the recommended time for treatment of this disease is in the fall and spring months when soil temperatures are in the 60- to 65-degree range.
One remedy that is also organic in nature is using sphagnum peat moss in the affected areas. Sphagnum peat moss is extremely acidic and topdressing the affected area leaves an acidic zone right at the soil level, where the fungus will struggle to survive and won’t be able to take hold.
One bag of sphagnum peat moss contains 1/3 of a cubic yard of moss which should cover 100 square feet.
Recovery from “take-all” is not overnight. The first step is to stop the fungus from growing and spreading. Over several months, you will begin to notice new green runners starting to establish in the yellowed, browned or bare areas. You can find sphagnum peat moss at your favorite garden center.
For more information call the Extension Office at 645-8204.