Tuesday, July 5, 2011

Anthracnose: A Closer Look

Unlike Dollar Spot, Foliar Anthracnose (fungal pathogen Colletotrichum cereale) is not as easlily identified.  In order to poperly diagnose this disease, it takes a little investigation and some time crawling around on the greens with a hand lens and camera.  This not our first bout with this disease.  As many of you will recall, we dealt with Anthracnose about this same time last year and were able to recover after some necessary applications of fungicides.

The initial yellowing of the turf caused by Foliar Anthracnose
 Typical symptoms of Foliar Anthracnose are a yellowing of the leaves starting at the tip and decaying downward as well as the presence of black acervuli on the leaf blade.  Damage can occur on both Annual Bluegrass and Creeping Bentgrass. If left untreated, large areas of turf can be affected with the end result being a very inconsistent and undesirable putting surface. Acervuli and the associated bristlelike setae can be seen in the picture below that I took with my camera through a magnification lens. To see a larger version, please click on the picture.

Acervuli (black spots) and setae (bristles coming out of black spots) can be seen on the infected leaves
Other than preventative applications of fungicides, recent studies have shown that a regular topdressing program as well as proper fertility can help to prevent this disease. Nobody likes to deal with the greens being topdressed regularly or the increase in fertility levels which can lead to slightly slower green speeds, but a common ground can certainly be achieved while meeting realistic expectations. The fact that these two measures can help to prevent this disease speaks volumes of the importance of our management practices.

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