Hi, I have a young 3-foot Allegheny serviceberry sapling I planted perhaps 6 weeks ago. It is not doing well and I noticed this growth on it. Doing some research led me to wonder whether it could be Apiosporina. All my other recently planted saplings (dogwoods and redbuds) are doing well, and this one got the same treatment at planting. It is in partial shade on a slope. If this is Apiosporina then it is common and widespread in serviceberries, according to my reading. No particular treatment other than removing the affected parts is recommended. However, the sapling is so small that I would be removing most of the tree if I were to follow this advice. I am wondering 1, whether I should just replace this serviceberry in the fall, and if that is the recommendation 2, whether I should be NOT putting in another serviceberry because of contagion. Thank you in advance for your expertise!
Your serviceberry has a rust disease which is a common problem of serviceberry.
Serviceberry is in the rose family, so it is susceptible to many of the same disease and insect pest problems that are seen in other species within the family (e.g. apples and pears). These rust diseases have 2 host plants and uses them both to complete its lifecycle. The alternate hosts are Eastern red cedars (Juniperus virginiana), Common juniper (J. communis), and Creeping juniper (J. horizontalis). No chemical control is recommended for ornamental plants. This will probably be an issue every year although the disease is worse in wet seasons. You can leave this sapling be for now. A replacement serviceberry would most likely become infected too. If you want to replace it choose another species of tree.
See our website https://extension.umd.edu/hgic/rust-diseases-trees-and-shrubs