FOREST HEALTH - HARDWOOD LEAF DISEASES

Like any biological taxum, trees are prone to a variety of diseases. Some are fatal. Others are more bothersome. Diseases can attack any tree part, but most diseases specialize on particular tree parts, such as leaves, fruits, flowers, stems, and roots. Most diseases are fungal, some are viral or bacterial. There are far too many tree diseases to provide a complete list on this website. Therefore, only some of the more common or important or severe diseasese will be thumbnailed.

To help identify a particular disease, knowing the correct species of tree is critical. It's also quite helpful to observe the affected tree part, note the symptoms, carefully look at disease fruiting bodies, and realize that diseases have particular life cycles and often change appearance over a period of time. Some diseases will be easy to identify. Others will be difficult. Sending samples to a laboratory, such as the Diagnostics Lab at MSU, requires a proper sample be taken. Time is important. Secondary disease organisms will begin to act on any tissue making culturing difficult, especially for diseases which require live tissue.

It's also important to realize that most fungi are either neutral or beneficial to trees. A group of root fungi called mycorrhizae are essential to nutrient uptake of many tree species. Wood rotting fungi are critical in nutrient cycling, as well as providing habitat for many wildlife species. Some forest fungi are edible, and tasty! Lastly, fungal fruiting bodies are often colorful and have interesting forms and life cycles. Artists conks are sought after by crafters.

Image Citations
All others - Bill Cook, Michigan State University Extension

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This site created and maintained by Bill Cook, MSU Extension Forester for the Upper Peninsula of Michigan, now retired.  He continues to respond to suggestions, questions, and corrections. Contact him at cookwi@msu.edu.