Black Knot Fungus #869826

Asked May 23, 2024, 4:54 PM EDT

Can black knot fungus spread to near by trees such as oak, ash, elm, etc - or only to cherry/fruit bearing trees? How should we dispose of the branches with black fungus on them?

Washington County Minnesota

Expert Response

Hi Mary, 

Thank you for reaching out! Here is a helpful UMN Extension article about black knot:

Black knot fungus primarily affects plum and cherry trees (see section titled "Trees affected by black knot in Minnesota"), so oak, ash, and elm trees are not susceptible and should be fine. 

Any infected branches should be burned, buried, or properly disposed of. Here is another article from Cornell on managing black knot:

Good luck! 

An Ask Extension Expert Replied May 23, 2024, 8:51 PM EDT

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