Pear Rust on Cherry tree?
Hi - The last two years my cherry tree has had what I would call 'rusty' leaves. Lots of spots and a very active ant/aphid collaboration. I was told that Cherry trees are prone to disease and figured I could help manage it by fighting the ants/aphids. It looks like it has spread to the neighbors trees, and possibly my vine maple. This is the first year that I see something that resembles marmalade coming from the trunk -- which is what got me to the page on your site about pear rust. If this is what I've got, how can we eliminate/manage it? The cherry tree has plenty of flowers in spring but bears very little fruit, that may also be an indicator of something?
Multnomah County Oregon
Thank you for your question about your cherry tree.
In answer to your specific question, pear rust must have a host plant for the fungus to survive year to year, and that host must be either juniper or cedar, depending on the specific fungus. Do you have either of those within 1000 feet of your tree?
There appear to be quite a few things going on with it, all probably caused by one fungus or another. A couple of questions: are the lesions on the leaves raised or flat? Or are they raised on the underside of the leaf, and flat on the top? Are there any other places on the tree that this 'oozing' is going on? Is the photo on the right a picture of 2 leaves, or one? Where did it come from on the tree? (It or they seem larger and more limp than the ones on the left.) I'd also appreciate a photo of the entire tree from a distance.
Are you able to take pictures of your neighbors' diseased plants, as well as your vine maple with problems? I'll try to research further with more information.