Fungus Invasion

By: Jeremy Maneol










Have you ever woke up one day and looked out the window just to notice large rings all over your lawn? The first thing that probably comes to your mind is that we have been invaded by aliens. Well we just aren’t that lucky. Your lawn has been invaded by a disease known as Brown Patch Fungus.

Brown Patch usually starts out in small circular patterns and can spread to several feet in diameter. It often has a patch of green grass in the center of the circle. The leading edge of the circle is kind of an orange-yellow color when the fungus is active. The base of the leaf will appear rotted. This is because the fungus is a soil born disease and infects the leaf closest to the soil surface. There will also be a rotten smell at the base of the leaf tissue. Brown Patch only affects the foliage and does not attack the root system of the turf.

Brown Patch has distinctive features, but is often confused with herbicide damage. Certain herbicides used can cause the same symptoms of yellowing or brown patches. The best way to tell the difference between brown patch and herbicide damage is to pull the leaf tissue from the runner. The base of the leaf will not appear rotten and will not have a putrid smell when dealing with herbicide damage. You will notice that the base will be dry and tan in color with no odor.

I am often asked where brown patch fungus comes from. Rhizoctonia is the name of the naturally occurring fungus that does the damage. When the conditions are right and the fungus is present it becomes active.

Brown Patch usually will occur through the months of November through May when the temperatures are below 80 degrees. I have also seen Brown Patch Fungus as early as September some years. Cooler nights and warmer days seem to spark up the disease. Brown Patch can also be triggered by rainfall, over watering, and high humidity.

There are several things a homeowner can do to control Brown Patch. First of all, do not apply excessive quick release forms of nitrogen during the fall and cooler months when the disease is most active. Try to use a fertilizer with slow release nitrogen with equal amounts of slow release potassium. Another thing and probably the most important is proper watering. Only water as needed and only water early in the morning between the hours of 2 a.m. and 8 a.m. when the dew is already on the ground. This will cut down on how long the foliage of the turf stays wet. One of the quickest ways to spread the disease is by mowing. When mowing try to always mow any infected areas last and be sure to clean of the mower blades after each cut.

There are also several chemical controls on the market. You can find these at your local hardware store. It is usually best to contact a professional when dealing with turf diseases. If the disease is not treated properly a lot of times more damage can occur. If you are not sure what you are dealing with give us a call, we do offer free lawn evaluation and estimates.

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