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| | St. Augustine grass begins to thin out as a result of gray leaf spot. |
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| | This photo shows the twisting of the blades on St. Augustine grass, a characteristic of gray leaf spot damage. |
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What's wrong with my St. Augustine grass? Many Rapides Parish homeowners are asking that question right now. For some homeowners, one problem could be gray leaf spot.
Gray leaf spot first appears as tiny brown to ash-colored spots with purple to brown margins that enlarge and become elongated or diamond-shaped. Sections of the leaf blade will turn yellow. In severe cases, lesions develop on stems and spikes and the leaves wither and die. Turfgrass may have a burned or scorched appearance resulting from death or spotting of the leaf blades.
Gray leaf spot develops rapidly with abundant moisture and warm weather. It is especially troublesome in shaded areas that remain damp for prolonged periods, in low-lying spots or where water runoff flows regularly. Under these conditions, the disease can cause serious thinning of the turf.
Ways to manage gray leaf spot - Avoid applying high rates of nitrogen fertilizer on moderately shaded lawns during summer. Water early in the morning, and only when supplemental water is needed. Avoid evening waterings that keep the leaf surface wet for long periods. Catch and remove grass clippings where gray leaf spot is a problem.
Several fungicides are recommended for gray leaf spot control. They are:
- Mancozeb
- Bannermaxx
- Lawn fungicide
- Fungicide VIII
- Heritage
- Bravado
- Daconil
- Concorde SST
For more information on application of fungicides or other lawn problems, contact Terry Washington at (318) 767-3968 or twashington@agcenter.lsu.edu.