This looks like muscle scale, Lepidosaphes beckii. Try scratching off the brown marks on the leaf, if they detach from the leaf and are filled with soft wet mater then you can be sure. Its a persistent problem in the south east. The scale is often in the surrounding environment so you may have to continually treat for it. If you don't treat it, it slowly kills small plants. However if the tree is small enough to cover with spray, neem oil and spinosad work really well so long as you spray every two weeks for several months. There is also imidacloprid systemic insecticide. This works well against the scale but it is very toxic systemic so its recommend after blooms and as a last resort.