Healthy lawn prevents patch

Take-all patch is the most destructive disease we have in our lawns, particularly on St. Augustine. Take-all patch, like most on our warm-season grass diseases, is most active in the spring and the fall, specifically in the spring during greenup. Integrated management is the best approach to preventing and controlling take-all patch in lawns. Take-all patch problems are closely related to soil pH. Maintaining a pH below 6.5 will reduce the severity of the disease.

I can almost guarantee that when a grass has a disease problem like take-all, the potassium levels will be low. Manganese deficiency also increases the severity of take-all, so supplements of this can be added. Fungicides can help control this disease, but they have limited effectiveness during the summer when a lot of the symptoms show up. Research has shown that the only effective times to treat are in the fall and again during early spring. When selecting a fungicide, look for Immunox Lawn Disease Control (liquid) or Fertilome F-Stop (granular) that contain myclobutanil. These two products are what you will find in most retail garden centers. Topdressing with peat moss seems to help control take-all patch disease. The recommendation is 3.8 cubic feet of sphagnum peat moss per 1,000 square feet. You might also try top dressing with compost, which has anti-fungal properties.

http://chronicle.augusta.com/life/home/gardening/2012-03-08/healthy-lawn-prevents-patch