Ohio State University Extension Bulletin

Ornamental Plants
Annual Reports and Research Reviews
2001

Special Circular 186-02

Infectious Disease Problems of Ornamental Plants in Ohio: 2001

James A. Chatfield,
Ohio State University Extension,
Northeast District/Horticulture and Crop Science;

Nancy A. Taylor,
Plant Pathology,
C. Wayne Ellett Plant and Pest Diagnostic Clinic;

Erik A. Draper,
Ohio State University Extension,
Geauga County;

Stephen Nameth,
Ohio State University Extension,
Plant Pathology;

Joseph F. Boggs,
Ohio State University Extension,
Hamilton County/Southwest District

Diseases of Note in 2001

6. Cristulariella Leaf Spot of Maple

Many in southern Ohio noticed this zonate, or bull's-eye, fungal leaf spot of maples in 2001. As noted in Diseases of Trees and Shrubs by Sinclair, Johnson, and Lyon: "Target spots have light centers and alternating light and dark concentric rings."

During moist weather, lesions may coalesce and in some cases defoliation may occur.

On the undersurface of lesions, with the help of a hand lens, you can often see conical or globular crystalline masses containing propagules of the fungus. This disease is typically a mid- to late-season disease. It is usually not prevalent each year, so controls are generally not warranted.

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