Orange rust fungi showing only on the back side of the leaves of southern dewberry plants.

Reference for southern dewberry rust:
https://aggie-horticulture.tamu.edu/syllabi/608/Lists/second%20ed/Rubustrivialis.pdf
"Pathological Problems: An orange rust caused by the fungus Arthuriomyces peckianus can causewitches’ broom branching and an orange discoloration of the leaves; various insects including spidermites can be problematic on the foliage."