Q.What Is Wrong With This Banana Shrub?
I have 2 of these shrubs. One is in full sun and the other, which is more of a tree form and more open, is under a well trimmed up Oak tree. Plenty of room for air circulation. Both have the same issue on the leaves. Pics attached of leaf.
Certified GKH Gardening Expert
This looks to be the early signs of Algal Leaf Spot, or possibly coupled with a bacterial infection.
Most bactericides and fungicides will take care of the issue: