Crabjoe: You won't be able to propogate a cutting taken now. Wait until the dormant season. Besides your vine needs all it's foliage this summer to increase the root system so as to maximize growth next yr.

The Fruitnut

You could take one of those lower shoots and bend it over and bury a section of it so it will root. That way, it should have its own roots by winter, but it will still be attached to the mother vine and contributing energy for maximum growth. Late next winter, just dig, snip and transplant.

Thanks for your thoughts folks.

Kiwinut... I completely forgot you can get grape vines to root by covering them with dirt, so here's what I'm going to try.

I going take one of those pots that come from nursery plants and cut a slit about half way down the side. About a 1/2" wide. This will allow me to take one of the lower vines to put into the container and till with dirt to get it to root. It'll also keep me from having to dig up it up in the fall after it's rooted.

Thanks again folks!!

I would wait if it were me in your situation.
If you don't want to wait, have some of that silicone "sticks to itself" tape handy 'cuz the cut stub will probably continue to "bleed" for a long time, weakening your vine to some extent.
Remember; Rootone is your friend, and make at least 2 (3 more likely) cuttings to root for when the others croak off.