Gray Leaf Spot Disease - Knowledgebase Question

Lake Worth, Fl
Avatar for gramsay007
Question by gramsay007
October 1, 2010

I have a problem with certain areas of my front lawn(St. Augustine). The grass is brown/dead in patches.

My lawn service repaired the bad areas with sod in June.

The same problem areas have returned.

The problem is a combination of cinch bugs, grub bugs and gray leaf spot.

Is there a suggested product to use for the gray leaf spot. None was found at Home Depot.


Answer from NGA
October 1, 2010
Gray leaf spot develops rapidly with abundant moisture and warm temperatures on St. Augustine grass. It is especially troublesome in shaded areas that remain damp for prolonged periods of time, or in low-lying spots, or where water runoff flows regularly. Under these conditions, the disease can cause serious thinning of the turf.

Leaf spots first appear 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 also 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.

To manage, avoid applying high rates of soluble nitrogen fertilizers on moderately shaded lawns during summer months. Water lawn 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, including azoxystrobin (Heritage), myclobutanil (Spectracide Immunox, Greenlight Fung-Away Systemic Granules, Eagle), propiconazole (Fertilome Systemic Fungicide, Ortho Lawn Disease Control, Bannar Maxx), and thiophanate-methyl (Fungaway Systemic Lawn Spray and Greenlight Systemic Fungicide).

In addition to management with cultural practices and/or fungicide applications, you might consider aerating your lawn to help with the drainage problem.

Good luck with your turf!

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