The mossy, greenish growth in the first photo are just lichens. They are harmless to the plant themselves but do tend to colonize plants that are struggling and produce a weak or sparse canopy. So they are not the cause of your viburnum problems but only a symptom of them.

Viburnums are prone to a soil pathogen - Verticillium wilt - that can cause die back and loss of foliage as you describe and will eventually kill the plant. It is difficult to diagnose, so suggest you take good photos and samples of the plants to your local extension office for assistance. If is IS VW, then you need to be careful as to what you plant in that area. Another VW-prone plant will have issues as well.

Verticillium wilt doesn't make the leaves disappear.

But viburnum leaf beetle would. Look at this info and, if still puzzled contact your county's Extension Service office

Viburnum leaf beetle:

http://entnemdept.ufl.edu/creatures/orn/beetles/viburnum_leaf_beetle.htm

Locate your local Extension Service office:

http://npic.orst.edu/pest/countyext.htm

When I look at the leaves they seem to be ok. just turn brown and drop from the top down. No sign of being eaten. I might add that the dead bushes pulled out of the ground pretty easily. Another note is that this land use to be an orange grove and I had problems with nematodes in the past when I tried to grow veggies. Had to use pots. The other thing is that this started with a bush at the end and appears to be moving slowly across the row.

Dried up leaves that just hang off the tree until they drop could very well be a sign of verticillium, as could the fact that the problem is progressing down the row of similar plants. But it is nigh on impossible to accurately diagnose something like this remotely and without examining the roots and checking out the wood firsthand. The suggestion to contact your extension office and to take in samples for an analysis is repeated. For the third time :-)

Thank you.