Disease in your St Augustine or Zoysia Grass?

December 20th, 2012

Disease in your St Augustine or Zoysia Grass?

Not (always) so serious...

Among the most commonly found, easily identifiable, and least devastating diseases you will find Grey Leaf Spot. This fungus creates small circular grey legions on the leaf blades. It usually does not kill the plant, but it can hurt the aesthetics of your lawn. Once the disease has been controlled or has abated naturally, the turf typically rebounds in short order. The leaf tissue that has been damaged only needs to grow out long enough to be mowed off, and then the turf looks anew. Some instances of this pathogen are so mild that they may not even require a fungicide treatment. The plant will simply maintain its aesthetics adequately enough that no one will notice it, or the disease will simply run its course.

Figure 1. Grey Leaf Spot on St. Augustine grass. Photo courtesy of University of Florida IFAS Extension1

Figure 2. Grey Leaf Spot legions on a St. Augustine grass shoot. Photo courtesy of University of Florida IFAS Extension1

Grey Leaf Spot on Zoysia grass.

Serious, very serious...

Pathogens that affect (St. Augustine or Zoysia) grass root-systems can be both difficult to recognize and diagnose. Often the symptoms are blamed on another cause, and the symptoms are therefore neglected, resulting in loss of turf. In order to confirm a diagnosis with soil dwelling pathogens one would need lab work to verify the suspicion. The problem is that soil dwelling diseases of St. Augustine (and Zoysia grass) can be brutally devastating, and they can do so quickly. If you are not certain, the best thing you can do is to call a professional, preferably one with a formal education in turfgrass management.

Figure 3. Disease in St. Augustine, variety Captiva. Notice the yellow halo.

Mushrooms

We get lots of questions about mushrooms in St. Augustine grass lawns in Tampa. Suffice to say that in all instances but one they do not negatively impact turfgrass. Other fungi that dwell in the soil but do not affect turf may produce mushrooms as a normal part of thier life cycle. The one pathogen that produces mushrooms and can afflict turfgrass is known as Fairy Ring. Rarely do we see it in home lawns, and in most every case we know exactly what it is. Controlling it can be a very difficult matter. Look for the identifying ring of mushrooms seen below.

Figure 4. Fairy Ring in turf grass. Photo courtesy of University of Florida IFAS Extension2

What You Should Do

Study the pictures included in this document and the list of symptoms below. If you see these types of things in your lawn, it might warrant further investigation. Sometimes university extension agents can be a good resource for diagnosing issues. You may need the help of a true turfgrass professional. Green Solutions Lawn Care & Pest Control is happy to provide free estimates for service if you suspect you need professional lawn care in the Tampa Bay area.

Look at this short list of symptoms that may point to a disease:

• Discolored patches are popping up in the lawn very quickly. Often the roots are no longer intact or they are black and very stubby.
• Look for circular shaped patches or conjoined circular patches of discoloration.
• These patches can often have a bleached color on the inside of the circle and a bright yellow halo on the perimeter. These are classic disease symptoms.
• Look for spots or legions on the leaf blades, especially those that look like the ones depicted in this article.

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Footnotes

1. These photos were taken from document PP204, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date March 2005. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. This photo was taken from document SS-PLP-7, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 1991. Revised February 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.