The Q&A Archives: Lawn Fungus

Question: I have a professional lawn company that mows and maintains my lawn. I have a beautiful St. Augustine lawn but I get a lawn fungus, brown patch, every year. The company treats it but it always comes back. It seems this year it came back quite early within a few weeks of the lawn turning green for spring. I want to prevent this from reoccuring but I don't know what to do.

Answer: Brown patch is most prevalent on St. Augustinegrass which has been heavily fertilized when night temperatures are above 68 degrees and day temperature are above 80 degrees. Dead patches of grass may start small but can grow and join together to make patches more than 3 feet apart. Sometimes, there will be a ring of brown, dead grass surrounding a patch of green grass. To control brown patch, fertilize St. Augustinegrass moderately in summer and if you irrigate, do it in the very late evening or very early morning.

Management plays the most important part in brown patch control. Don't apply excessive nitrogen. Use only enough to maintain a reasonably green and attractive lawn. Water only when the soil is dry and then soak the soil to a depth of 5 to 7 inches. Water between 10 pm and 10 am.

Despite our best management practices brown patch may appear. Sometimes a fungicide may be needed to suppress the fungus growth and protect the grass from attack during periods when conditions favor disease development.

Remember that control and management of the disease are key. Don't wait until you need a fungicide. Use fertilization, watering and mowing properly to avoid brown patch.

Labeled fungicides such as Turfcide 10G and Hi-Yield Lawn Fungicide Granules with terrachlor or PCNB; Greenlight Fung-Away Systemic Granules with thiophanate-methyl, Ortho Lawn Disease Control and Ferti-lome Systemic Fungicide with propiconazole and Sprectracide Immunox with myclobutanil will stop the brown patch fungus. Read the label carefully and use the rate and timing that is indicated.

Best wishes with your turf!

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