Hawthorn tree diseases - Ask Extension
Attached are a few photos of a pathogen or growth on my Hawthorn tree.
The tree was planted in July 2004 and has been healthy all these years. Thi...
Knowledgebase
Hawthorn tree diseases #842992
Asked July 28, 2023, 10:03 AM EDT
Attached are a few photos of a pathogen or growth on my Hawthorn tree.
The tree was planted in July 2004 and has been healthy all these years. This is the first I've seen of this disease and it is on more than one branch. What causes it and can the disease be eradicated?
Please advise on the best treatment so that I can save the tree!
Oakland County Michigan
Expert Response
Hello,
This appears to be Cedar-Hawthorne Rust disease. This will rarely impact the health of the trees affected, and is mostly cosmetic. This disease is spread when junipers are planted too close to hawthorne trees. There are resistant varieties of hawthorne, but it looks like yours is not a resistant variety. If you want to treat this, you need to treat both the juniper and the hawthorne tree, at different times of the year due to the life-cycle of this fungal pathogen. The link below discusses the fungicide that is most effective, and the timing for spraying the juniper and the hawthorne.
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/rusts/cedar-hawthorn-rust
Alternatively, you could make a decision to tolerate the disease, especially because there may be junipers in the vicinity that do not belong to you which you will not be able to maintain. Also, these trees are attractive to birds and pollinators that could be harmed by the fungicide.
https://extension.umn.edu/plant-diseases/cedar-apple-rust#managing-rust-on-apples%2C-hawthorns%2C-and-other-plants-in-the-rosaceae-family-1172760
I hope this is helpful.
Thank you for contacting Ask Extension.
Ruth
This appears to be Cedar-Hawthorne Rust disease. This will rarely impact the health of the trees affected, and is mostly cosmetic. This disease is spread when junipers are planted too close to hawthorne trees. There are resistant varieties of hawthorne, but it looks like yours is not a resistant variety. If you want to treat this, you need to treat both the juniper and the hawthorne tree, at different times of the year due to the life-cycle of this fungal pathogen. The link below discusses the fungicide that is most effective, and the timing for spraying the juniper and the hawthorne.
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/rusts/cedar-hawthorn-rust
Alternatively, you could make a decision to tolerate the disease, especially because there may be junipers in the vicinity that do not belong to you which you will not be able to maintain. Also, these trees are attractive to birds and pollinators that could be harmed by the fungicide.
https://extension.umn.edu/plant-diseases/cedar-apple-rust#managing-rust-on-apples%2C-hawthorns%2C-and-other-plants-in-the-rosaceae-family-1172760
I hope this is helpful.
Thank you for contacting Ask Extension.
Ruth
