Diseased heritage river birch
This is not a disease but is caused by an insect called spiny witch hazel gall aphid.
This aphid is a common pest on birch, particularly river birch. It has a complicated life cycle in that it alternates between two hosts: birch (Betula) and witch hazel (Hamamelis spp.) The aphids become active in the spring when the leaf buds are opening. The growth and reproduction of the aphids is rapid, and the leaves soon develop characteristic “corrugations”. The corrugations on the undersides of the leaves fill with aphids and a white granular material. Winged aphids develop on the birch leaves then seek witch-hazel on which to lay eggs and complete the life cycle. This activity takes place before the end of June.
The damage is mostly cosmetic and does not cause serious problems for birch trees. Predator insects like ladybugs typically feed on these aphids reducing the population. The aphids will not be around for the entire summer.
If needed, you can spray with horticultural oil. Be very careful to read the label, as spraying when temperatures are too high can damage leaves. You need to target the undersides of the leaves with the spray.
I just thought you would find it interesting that I had a witch hazel tree plant about 6' from the river birch about 2 weeks ago. I guess they aren't such good neighbors to each other.
thank you for the information.
Yes, but I still think this would have happened. It is really a very common problem. Enjoy both plants!