My mom (located in Vancouver, BC), isn't great with technology and asked if I could try to identify what was wrong with her two Mulberry trees. I spent quite a bit of time researching and found several great sites that listed diseases/pests that affect Mulberry trees, but none of them really matched the issues she is experiencing.
Her trees are roughly 3 years old and appear to have little clusters of yellow stuff growing on the bark, along with a section that seems to have reddish brown staining. I've attached images of the two trees and marked some of the issue areas.
Based off the information I found online, I asked her about the condition of the leaves and she said they are still green but have slowly starting yellowing from the tips of the leaves inward (not in blotches). She also clarified that she hasn't seen any kind of powdery substance on the tops or bottoms of the leaves.
Any help identifying the issue and potential solutions is greatly appreciated.
Below are 2 of the better links I found in case they end up being useful to anyone else:
12 Mulberry Tree Pests and Diseases
Texas Plant Disease Handbook - Mulberry