Fungus Among Us

Take-all root rot.

Brown patch found in St. Augustine grass.

Gray leaf spot.

Our lawns have taken a tremulous stomping this year. In January through February we had below freezing days in addition to snow, followed by consistent cool weather from March to mid-May. Then  we had a stretch of 90 degree temperatures and drought. Now that the continued hot summer nights and high humidity are here, we can expect several fungi problems in the lawns. Begin looking for these common lawn diseases.

 Take-all root rot is currently the most common disease in our lawns preferable this summer. The disease resembles brown patch, however, the patches for take-all are more irregular in shape than those of brown patch. Because it is a root disease, it actually kills the turf, whereas brown patch only kills the leaves. A key symptom of take-all root rot is the ease of lifting the damaged material from the soil. Reduce the stress, use proper irrigation, use proper cutting heights and avoid high nitrogen fertilizer to minimize the disease.     

Brown patch is common in most grasses but especially in bermuda, centipede and St. Augustine. The symptoms appear in a wide circular pattern usually brownish to gray. High nitrogen, deep thatching and watering in late afternoon are problems that can cause this fungus to increase. Brown patch will occasionally show up in the summer, but is more likely to become a problem in the fall beginning in late September as the temperatures cool down. The best time for brown patch is when daytime temperatures are less than 85 degrees and nights are above 50 degrees.
Gray leaf spot is mostly found on St. Augustine and is common during long periods of hot, humid weather. Lesions of gray leaf spot are more tan to gray and margins are more purplish-brown. From a distance, the affected areas may have a dirty yellow appearance. Gray leaf spot is often found in shaded damp areas of the lawn. Our lawns are struggling and these are some things we can do to help. Using proper cutting height and frequency, reducing thatch layer and minimizing soil compaction are simple corrections to limit fungus among us.

For more information on lawn diseases please see the Plant Disease Center's Publications on turf.

7/21/2011 8:44:15 PM
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