Orange growth on tree leaves and seed pods

Asked May 29, 2018, 5:54 PM EDT

Can you identify and tell me if the residue is harmful to the tree and surrounding trees. The affected tree is in among old oak trees which I would not want to become affected as well. I have attached a photo of the problem. Thank you!

Clackamas County Oregon

2 Responses

The tree has a fungal disease called "rust". Looks a lot like rust on metal but no, those are fungal spores that can spread to other trees. But only specific trees. In this case, it kind of looks like the tree is a serviceberry (Amelanchier sp.) but that is a guess. I suspect this is what we call Pacific Coast Pear rust which will not be a problem to the oaks. Here is some more info on that disease:

Thank you for your time and sharing your expertise.