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Southern Lawns and Greyleaf Fungus

by Gabby Hyman, All About Lawns Columnist

Grey leaf spot disease can attack St. Augustinegrass lawns in early summer.  Caused by a fungus, the disease shows up as circular-shaped spots or tan lesions on the blades of grass. If left untreated, a runaway case of grey leaf spotting can take down an entire lawn. While the temptation is to over-treat the condition with herbicide you may have better results by cutting back on nitrogen fertilizers and reducing your watering.

The fungus (Piricularia grisea) is especially prevalent in St. Augustinegrasses in the American South, although spotting has been reported on ryegrasses and other common lawn varieties including tall fescue as far north as New York State. Fungicide has proven effective in treating the turf spotting if used early in the disease cycle, but is less so once the fungus has a foothold. If you're going to have to take aggressive measures, it may pay off to call in an expert from your local lawn care service.
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When There's a Lawn Fungus Among Us

The key to saving a lawn when grey leaf spot comes to town is to diagnose it promptly. You'll notice that individual grass blades are withering, have lesions, and your entire lawn surface appears to thin out.  If you live in a hot, muggy climate, humidity and excess moisture on your lawn can really create problems. Avoid watering late in the day or early evening.

One thing about using fungicide is that it's costly and not always effective. Cut back on applying soluble nitrogen fertilizers during the heart of summer, especially if your lawn has a moderate amount of shade. And you may consider cutting back on using any herbicides that ultimately weaken St. Augustinegrass and may leave it vulnerable to disease and fungus.

About the Author
Gabby Hyman has created online strategies and written content for Fortune 500 companies including eToys,, Siebel Systems, Microsoft Encarta, Avaya, and Nissan UK.

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