Large Patch fungus in lawnDuring the cooler weather, your lawn may begin screaming out to you, “There’s a fungus among us!” Mind you, a lawn can’t talk with words but it can tell you something is wrong in other ways - Namely, by showing symptoms of disease.

A commonly seen disease this time of year is Large Patch fungus. This fungus affects all warm-season turfgrasses. It’s active when nighttime temperatures range from 60-75 degrees and daytime temperatures don’t exceed 85-90 degrees. These temperatures are usually seen in the Spring and Fall, but can also occur during mild Winters. Like other fungi, Large Patch also requires adequate moisture in its environment to thrive, so be careful of your irrigation practices.

This disease affects the blades of the grass and will not kill the entire grass plant. It typically begins as small patches that turn yellow, then brown, as the grass blades die. Just like the blob seen in sci-fi movies, Large Patch starts out small but can spread to create large damaged areas if not controlled. An interesting display of Large Patch fungus in a lawn is the “donut effect” it may create. In diseased areas, you may see a ring of rotten grass with some green grass in its center; hence, looking somewhat like a large unsightly donut pattern in your lawn.

As ugly as Large Patch can look, it’s important to remember this disease does not kill the entire grass plant. Over time, the rotten grass left in the wake of Large Patch fungus will naturally decompose and new grass blades will grow. Mowing will also remove the dead grass blades. It must be mentioned, though, that active Large Patch fungus can be spread mechanically. In the event an area with active Large Patch is mowed, recommendations are for those areas to be mowed last and mowing equipment rinsed to prevent further spread of the pathogen.

In order to stop the spread of Large Patch in your lawn, a fungicide application should be made. This will only stop the spread of the disease though; it will not cause the grass to grow faster or green up. New grass will grow in eventually, but this can be a slow process in the Fall and Winter, as turfgrass is heading toward its dormant period.

Keep in mind, there may be other causes for brown patches in a lawn. Insect damage and improper lawn maintenance practices could also be a culprit, as well as many other variables. If you see discoloration in a lawn and aren’t sure what the cause is, contact us for a complimentary lawn inspection.