Knowledgebase
Catalpa tree issue #937218
Asked June 29, 2026, 2:33 PM EDT
Washtenaw County Michigan
Expert Response
In the absence of other evidence of insects or disease, the most likely cause is Verticillium wilt. MSU Plant and Pest Diagnostics Lab can definitely diagnose the problem with appropriate samples. This information explains how to collect a good sample and current pricing: https://www.canr.msu.edu/pestid/submit-samples/wilted-trees-and-shrubs.
There are a few other diseases that could explain these symptoms. Extreme heat and drought can also cause similar symptoms, but I would expect those symptoms to be more widespread on the tree or on the side of the tree more exposed to sun and wind.
For more information:
https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/catalpa/leavesdiscolored.html
https://extension.psu.edu/catalpa-diseases
To locate a certified arborist to look at your tree: https://www.treesaregood.org/Find-an-Arborist