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Anthracnose tree help #925283

Asked March 02, 2026, 12:12 PM EST

I have a large oak tree that appears to have anthracnose. It drops leaves throughout the summer, and new leaves grow back but are smaller than normal. What fungicide should I use, and when is the best time to apply it?

Saginaw County Michigan

Expert Response

Good afternoon and thank you for reaching out. Do you happen to have any photos that you could attach to this question? Photos really help our experts provide a more solid recommendation. In the meantime, I will refer this question to one of  our educators with tree expertise.
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Hello,
Below is an article about oak anthracnose, including treatment options. If the tree is large, it may be hard to spray the upper canopy to get proper coverage. 
https://extension.umn.edu/plant-diseases/anthracnose-trees-and-shrubs

Fungicide application should begin at bud break then repeated on a weekly or bi-weekly schedule until temps reach 60 degrees or above. 
https://extension.psu.edu/anthracnose-on-shade-trees

Sanitation of leaves dropped in years past as well as dead branches is important to reduce inoculum in the area.  Generally, the leaves are affected due to poor air flow in the area; increasing airflow is recommended. 

Lastly, I do highly recommend testing the soil near the tree to ensure it has the proper pH and nutrient levels to support the tree. Too high of a pH (over 7.0) can also cause issues in oak trees. 

Please feel free to reach out if you have any questions. 

Thank you,
-Julie
Julie Crick Replied March 05, 2026, 11:40 AM EST

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