Hemlock Diseases
Gary W. Moorman, Professor of Plant Pathology
| Disease | Symptoms | Pathogen/Cause | Management |
|---|---|---|---|
| Leaf spot | Irregular, reddish-brown spots on the upper leaf surface form while brown spots occur on the lower leaf surface. In severe cases, leaves may fall prematurely. | Gnomonia caryae | No control is recommended since the disease occurs late in the season and little damage results. However, raking and destroying leaves in the fall can reduce the amount of inoculum near the trees. |
| Microstoma, downy, or white leaf spot | Pale yellow spots of various sizes are observed on the upper side of the leaf. The lower side of the leaf spot appears white or powdery. In severe cases, a witches’-brooming occurs on branch tips (= large numbers of twigs). | Microstoma juglandis | No control is recommended. White, bur, shingle, overcup or post oaks are also susceptible. |
Fabrella needle blight (PSU Dept. of Plant Pathology collection) From the PA Department of Natural Resources.
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