You'll need some rubber gloves, a cotton glove and round up. Put on the rubber glove, cover with a cotton glove and wet the cotton glove with round up. Rub the leaves of the weeds with the gloved hand, keeping it away from the moss.

i thought roundup brand herbicide (glyphosate active chemical) does not affect moss?
if you wanted to try that by spraying a small area, would save you some time, in my opinion, instead of using the technique posted above.

Why does spanish moss grow on some trees and not others? For instance my Live Oaks, Chestnut Oaks and Crepe Myrtles are covered in the stuff but my hickories hardly have any, even though they are growing right next to each other. Don't think it's scaliness of bark because though hickories do have smoother bark than the oaks, Crepe Mytle bark is even smoother. I'm not trying to get rid of the moss, I'm just curious.