Yellow/orange spots on serviceberry
I just noticed these yellow/orange spots about 1/2 inch across with a rust-colored center dot. They are on the underside of nearly all the leaves of this small tree. Is it my imagination, or did the color come through to the top of the leaf in the last 2 or 3 days? Definitely there now.
I have another Serviceberry in the yard which is unaffected.
Kent Island, Queen Annes County.
Looks like serviceberry rust. One of your trees is either naturally more resistant or it is in a location that stays less wet and dries more quickly or has a less dense leaf canopy. The wet cool spring has resulted in a lot of rust on serviceberry this year. In future years, you may not see it at all.
Here is what rust is and how to manage: http://extension.umd.edu/hgic/rust-diseases-trees-and-shrubs
No treatment is recommended at this time.