Answer: Brown patches in lawns can be hard to diagnose. While the disease brown patch does cause patches of dead grass, other things can cause the same symptoms. If the area is poorly drained and water stands on a spot for more than 24 hours, the grass roots will rot, causing a dead patch. If you have a sodded lawn less than one year old, it is possible the soil underneath the sod was never plowed to relieve compaction. Where the sod has rooted poorly, brown patches will develop as dry weather sets in. If one part of the lawn was once used as a baseball home plate or a soccer goalie area, the earth beneath is almost as hard as concrete. It?s easy to see why green grass would turn brown there.
If you eliminate environmental causes of the brown patches in the lawn, what you are seeing might be a disease. True 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 will be green. Early in the morning during hot, damp weather you might see a white fungal web at the edge of the dead grass patch.
Hope this helps you determine just what the problem might be.
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