Answer: River birches are usually healthy with few pest or disease problems compared to other types of birches. Unfortunately, based on your description I am not certain what is happening to your tree. The defoliation could be related to dry weather and/or poor rooting or root damage, and the orange bumps might be signs of aphid damage or possibly a gall of some type. Very often a tree that is stressed will be attacked by a pest or disease, so I suspect there are several problems at once. I would strongly suggest you work with your local county extension to obtain a specific diagnosis of the problem(s) and based on knowing that, decide how to proceed. If a chemical control is needed, they will have the most up to date information on what to use and how/when is best to apply it. Alternatively you might consult with a skilled, professionally trained and certified arborist with experience in ornamental trees. Good luck with your river birch!
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