You Are Here: Management Updates 2003 Archive May 30, 2003

Date: May 30, 2003
Category: Diseases
Subject: Fusarium Patch, Yellow Patch, Red Thread, Bacterial Wilt, Abiotic Problems

The cool, wet weather diseases continue to dominate the turf problems. Fusarium patch (pink snow mold) looks and acts like hot weather Pythium blight- i.e. it often produces coppery to greasy leaf blades and is easily streaked by mowers and water. It is common in golf courses, apparently as far south as Virginia this year, and has even been found on home lawns. Fungicides are recommended for golf courses because of the foot traffic and frequent mowing although spot treatments are sometimes sufficient. The best curative fungicides are not available for lawns any more. In lawns, spread of the fungus can be minimized by mowing the lawn when it is dry (very difficult lately) and avoiding any nitrogen or lime applications. Although the leaf blades can be badly damaged, it is likely that the turf will recover quickly once the weather becomes warmer and drier. Temperatures in the high 70s are the equivalent of a fungicide application. Next week's weather report calls for most days in the 70s, so this should end Fusarium patch and yellow patch (cool-season brown patch). Fusarium patch can pop up again in shaded or poorly drained areas, but it usually requires a series of cool, wet days. Warm to hot days in between cool, wet ones will prevent the disease from becoming seriously active again.

Red thread is also rampant on many lawns. Although the books say that this disease is most common in compacted, droughty, low N areas, this fungus loves wet weather and will be active on even well managed lawns. As with other spring diseases, a few warm, dry days will end, or at least greatly reduce, it.

Bacterial wilt has been diagnosed on Poa annua from greens with very poor root environments. As always, the solution is to correct the soil problem and overseed with bentgrass.

Some abiotic problems have also been diagnosed- patches of off-color grass not associated with any apparent fungal activity and uniform patches of Poa annua with brown outer leaves, but green, healthy centers. The continued low sunlight and record breaking rainfall have not favored uniform turf growth. Perhaps next week's message will contain more typical summer reports.

- Submitted by: Dr. Gail Schumann