Something wrong with my River Birch

[Myriverbirch]

A few branches of my river Birch tree (which is still a young tree, maybe 5 ft tall) have leaves that look curled up and shriveled. Most of the rest of the tree looks very happy. Does anybody know what is going on or what is this?

 

[ATH]

River birch aphid?

White-Splattered and Corrugated River Birch Leaves

What’s causing some river birch leaves in Ohio to appear corrugated and others to splattered in white paint?

bygl.osu.edu

 

[KTSmith]

Oooh, I like that call. My kneejerk response to the image was "What's causing the sooty mold"?
The OP should look closely at those white patches, particularly on the margins with green tissue. If the patches look like thick paint splatter in 3-D, ATH made the right call.

 

[JD3000]

Witch hazel/birch aphid