You Are Here: Management Updates 1999 Archive September 27, 1999

Date: September 27, 1999
Category: Diseases
Subject: New Bentgrass Disease Confirmed

A new disease of bentgrass was documented in Connecticut on September 27, 1999. It was first described in 1998 by Dr. Peter Dernoeden in Maryland. It appears in August and September as small tan to reddish spots (dollar spot size) that may look like ball marks. It is caused by a foliar fungus that produces numerous dark fruiting bodies (pseudothecia) in the infected leaves. The proposed name of this new fungus is Ophiosphaerella agrostis, named for its bentgrass host.

The CT superintendent reports that it has primarily been on his practice green (Cato bentgrass) since early August, and about 40 or so spots developed. They somewhat followed mower wheel patterns. This does not seem to be an aggressive problem like gray leaf spot, but the fungus does produce a lot of spores in the fruiting bodies of the infected leaves. It would probably be prudent to mow affected areas last or wash the mower before moving to nonaffected areas. Very little is known yet about cultural practices. Dr. Dernoeden recommends thiophanate-methyl (e.g. Cleary's 3336) + chlorothalonil (e.g. Daconil) weekly or the problem will recur.

There is no official name for this new disease yet. "Fall spot of bentgrass" has been suggested.

- Submitted by: Dr. Gail Schumann