Danged computer froze up before I could post the second picture....I'll put a close up as soon as the stupid thing finishes booting up.

So here's the close-up picture of one of the leaves and you can see the tiny black specks that are some sort of pest - they're smaller than fleas but they jump around when I touch them. The browner leaves (more infected) have dozens or hundreds of them, mostly on the underside of the leaves.
No holes or chewing on the leaves - they just start with brown spotting then turn all brown and dead and fall off.
Any ideas what they are and what I need to do?
My google search didn't yield anything remotely like this.

That looks exactly like grapevine aphids...
..they almost made me stop growing grapes

c9, search google for "grapevine aphid"..

they can also destroy the roots of cultivated grapes

I had to resort to systemics/imidacloprid to finally get mine under control...you're not picking now so I would cut them back for the winter and get on a spray/drench program

Corrie

Thanks, Corrie.
From the pictures I found online, the grapevine aphids looked tan-brown and these are dark black, and the regular old aphids that I'm used to are much bigger, maybe poor googling on my part, but I've got to do something.
They're my hubbie's grapes so hopefully I can get him to follow this advice.

Maybe they are some kind of mite? Either way, it's time to spray. I'd try some insecticidal soap, neem oil (works great on mites if that's what it is), or some paraffin oil. You do need to do something ASAP though. It looks bad! FWIW I had mango scales bad.. Neem didn't do much but parra f'in knocked em out in two treatments two days apart.

It's too late for a systemic now. They'll be toast by the time it's up taken.