Brown Patch – Causes

Q: My fescue lawn looked great until a few weeks ago. Now there are big yellow spots that seem to get bigger each day. Is this “Brown Patch”?

A: Many homeowners blame any turf dead spots on a disease called “Brown Patch”. It’s a common fungus disease on lawns, particularly fescue lawns.

Brown patch spots are small to begin with but in warm weather they can enlarge rapidly. Seen from above, the patch will look like a doughnut – a ring of tan grass having a patch of green grass in the center.

Individual grass blades will be brown down to the crown – where the blade emerges from the ground – but the crown itself will be green. Early in the morning during hot, damp weather you might see a white fungal web or dark green grass at the edge of the dead patch.

There are other conditions that cause dead brown spots: soggy areas, hard soil and mower fuel spills, to name a few.

Before you reach for the lawn fungicide, eliminate the other conditions. Since brown patch is associated with watering in the evening and watering too often, change your irrigation habits to one deep soaking per week in dry weather.

If you feel sure the spots are caused by a disease, spray with a fungicide like chlorothalonil (Daconil, etc) or myclobutanil (Immunox).

Changing the conditions that cause brown patch is not easy, but once you see the price of a bottle of fungicide you’ll reconsider the effort. Remember that summer fertilization, drought stress, constant wetness and hard soil all predispose fescue to disease. Sometimes it’s easier to plow it up and start over in the fall than it is to battle disease all summer.

Turf Diseases
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