Dead Patches in St. Augustine - Ask Extension
My healthy St. Augustine yard from last year is showing several dead patches this spring. Some of the grass blades are a yellowish color, but not all....
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Dead Patches in St. Augustine #182264
Asked May 16, 2014, 11:59 AM EDT
My healthy St. Augustine yard from last year is showing several dead patches this spring. Some of the grass blades are a yellowish color, but not all. I'm concerned that my lawn my have a fungal disease. Comparing the attached photos to what I've read online, is this Take-All Patch? What is the solution?
Dallas County Texas
Expert Response
From Texas A&M research, 2003 (http://williamson.agrilife.org/files/2011/07/PEATMOSS_TOPDRESSING_for_TARR_3.pdf)"SEARCH FOR A PRACTICAL DISEASE CONTROL ON DALLAS HOMELAWNS
We used two approaches to control the TARR disease in field investigations on area lawns
during the past three years.
One approach utilized conventional fungicide sprays with Terraguard ®, Bayleton®, Heritage®,
and Banner Maxx® using 2.9L of spray per 10 m2. A second approach utilized topdressing lawn
care products including (1) manure compost and (2) sphagnum peat moss. Manure products can
enrich the microbial number and diversity for variable lengths of time and low pH products like
peat moss had been shown to suppress the Gaeumannomyces fungus in previous research. While
some of the manure based topdressing regimens demonstrated improved turf grass growth,
effects on disease control were only partial and limited in duration. Research field plots with the
fungicides Terraguard ® (4 - 8 oz) or Bayleton® (2 oz) treatments gave good results for
controlling the take-all root rot symptoms. Success with fungicide treatments was better on a
lawns maintained under shaded conditions compared to lawns in full sunlight.
A second approach with topdressings used low pH topdressing with sphagnum peat moss. This
topdressing approach has consistently demonstrated TARR disease suppression in field studies
during the past two years. Our field comparisons of manure compost vs. peat moss topdressings
indicate the peat moss to be a more effective long-term approach for reducing symptoms of the
TARR disease. Some of the older research literature on the fungus causing TAP indicates its
aversion to low pH. This might explain how the peat moss (pH = 4.4) controls the fungus on
exposed stolons and roots where the disease is active."The yellowing may also be confused with brown patch. Here's how to tell the difference: From: http://today.agrilife.org/2002/05/22/problems-strike-st-augustine-lawns-all-over-the-south/"Take-All Root Rot can often be mistaken for Brown patch. These two diseases can be distinguished by pulling on the leaf blades of the yellow to brown leaves. Leaves of Take-All Root Rot plants are still firmly attached to the stolons, while leaves with Brown patch can easily be pulled away from the stolons. Also, Brown patch rarely causes the roots to turn black.“The best time to treat for Take-All Root Rot is in the fall and spring when the soil temperatures are in the 60- to 65-degree temperature range."I hope these sites provide you with the information you need. Please let us know if we can be of further assistance.David Weber, Help Desk volunteer, Dallas County Extension Service
