You Are Here: Management Updates 2000 Archive August 4, 2000

Date: August 4, 2000
Category: Diseases
Subject: Summer Diseases

Summer weather finally arrived, and many disease fungi took advantage of the wet conditions to become extremely active. Some greasy looking turf with white mycelium turned out to be BROWN PATCH (Rhizoctonia) and/or FUSARIUM BLIGHT (a summer leaf disease- not necrotic ring spot). In one case, the FUSARIUM BLIGHT actually had a pinkish color to it because of the tremendous spore production. DOLLAR SPOT spot was very active and difficult to control even where fungicides had been applied. The heavy rains and significant turf growth greatly reduced the control intervals of treatments. PYTHIUM BLIGHT may have been briefly active, but the cool night tonight and drier days for the weekend will stop it as well as any fungicide. GRAY LEAF SPOT has still not arrived in New England, as far as we know, but it is definitely active farther south (NJ and PA). LEAF SPOTS and BLIGHTS (Bipolaris spp., Drechslera spp., and Leptosphaerulina) are active. The first two fungi are causing crown and root rots in wet areas and especially on fine fescues.

A diagnostic note: Although white mycelium is associated with Pythium and dollar spot (Sclerotinia), many fungi look white when they are young and fast growing. Both the red thread fungus and the brown patch fungus were active and white in the recent wet conditions. As they mature, they will take on their more typical colors, but in the early stages it can be confusing. It often takes a microscope to be sure.

- Submitted by: Dr. Gail Schumann