King Crab Apple Tree
We have what I believe is a King Crab Apple. We think are rust spots on it and are wondering what we can do about it. There's also a larger tree overhanging it. We don't know if that's part of the problem or not. I'm attaching some pictures of the two trees. If you need to call me, my phone number is 517-676-4510. Thank you for your attention to this matter. Sincerely, Leon J. Herriman
Ingham County Michigan
What you see on your crabapple may be cedar apple rust or cedar hawthorn rust. Both of these require two hosts to reproduce -- cedars and rosaceous trees like crab apples. If there are any red cedars nearby they may be leading to the spread of the rust.
- You can read more about these rusts and management options here: https://www.extension.purdue.edu/extmedia/BP/BP-138-W.pdf
- Cedar rusts: https://www.canr.msu.edu/ipm/uploads/files/WoodyLandscape_PDFs/CedarRust.pdf
- Cedar apple rust: https://www.canr.msu.edu/ipm/diseases/cedar_apple_rust