This is a single course offering, based on the pathology component of a regular OSU class (PLNTPTH/ENTMLGY 5110) aimed primarily to professionals in the tree care industry, including arborists, landscapers, forest managers, and extension educators, but also curious and interested people in the community at large, including master gardeners and private citizens. Purpose of the course. The course is designed to provide the basic knowledge necessary to recognize major diseases of forest and urban trees, and to apply the foundations of the discipline to new and unknown diseases of trees.