Photo by Tom MacCubbin
Gardeners are waking up to an almost overnight yellowing of their lawns. Usually the symptoms start out a very light yellow color and over a few days turn orange to tan in circular to oblong patterns. Now take a close look and you might see a bit of green in the center of these areas. It is called the ‘donut effect’.
That yellowing look to many lawns is likely caused by the brown patch fungus also during the colder weather called the large patch fungus. It’s encouraged by the cool dampish weather and seems to affect mainly St. Augustine, zoysia and bermuda turf types. By the time you see this fungal activity the disease is well-established and done most of its damage.
Applying a fungicide can help prevent the spread of the disease, to other turf areas of the landscape. It is not going to help with areas already in decline. Garden centers have a number of good fungicides labeled to help control this disease. Pest control companies also have an arsenal of newer products not yet on the home market that may give even better control.
When lawns are affected yearly by brown patch, an early November fungicide application is often recommended. This is normally following a month later by a second application and a third application in late winter.
The good news is this disease normally does not kill a lawn but does make it look bad until spring. Affected grass blades remain brown but the runners are usually green. The lawn then regrows new blades come spring when given normal care. Do keep the site moist but not overly wet during the winter and apply a fertilizer in spring.