That's right, it does not harm the trees as some people think. People say "the tree is declining because of the moss growth", when actually the opposite is true. A heavy growth of either ball moss or Spanish moss an indicator that your tree is unhealthy. The moss grows more as the leaf canopy thins out.
I know a couple of people who reduced their moss growth in live oaks by spraying the tree with soluble fertilizer. Something like Miracle Gro, in a pump sprayer or hose end applicator wouldn't hurt. Evidently it's good for the tree and bad for the moss, but I'm not sure of that. In any case, anything that encourages healthy leaf growth on your tree will reduce moss growth.
Only one of my live oaks has some Spanish moss, and it's the one beside our driveway. I always figure it's protesting the fact that I drive my car back and forth across its roots, but . . . the driveway's been there for a lot of years so it should have adapted by now. A huge clump of moss is sitting on the driveway as I write this. Ball moss? Well that grows on anything that stands still, there are clumps on the power lines and I had a couple of clumps growing on the screening of my pool cage last summer.
