Need to radically prune a wild grape vine
There is a wild grape vine at my house. For decades it has been guided back and forth across a trellis suspended over the front porch. Throughout the spring, summer and fall it provides a really nice shade and fruits very small bunches of grapes that are not all that tasty. I cannot find an answer to my question regarding pruning of this monster. I'd really like to prune it back to places where the vine is about an inch or so in diameter. There are no buds or shoots located on these larger vines. So, if I really want to cut it back, can I do so without killing the thing? Can I graft some younger shoots into it along the way?
Roanoke County Virginia
You need to find some young canes arising from where the stem goes from the vertical trunk to the horizontal tangle. Mark that cane or canes with something and then cut off the woodier part beyond it. Get the old woody stuff out the best you can in pieces without damaging the canes you selected. Then go back th the base of your selected canes and cut off the side shoots back to just a few buds. What you will end up with is a winding stick with stubs on it, from which new canes will arise this year. Each year or two you will select more new canes back where it becomes horizontal to be "renewal" canes. As you clip out the oldest canes, the renewal canes are laid out to be the new foundation on the structure. It will be a nightmare to do the first time because it is so hard to follow a cane, so you will have to let size and woodiness dictate and if you make a mistake, don't despair, it will grow new ones. It is the same principle as this four arm kniffen training, only you are doing it on a horizontal overhead. You can pull a straight cane out on each board, but I suspect it is too tangled to do that now so you will just have to follow them the best you can. http://digitalpubs.ext.vt.edu/vcedigitalpubs/2316189396242366/MobilePagedReplica.action?pm=2&fol...
See page 14 and imagine that structure on its side overhead.
Here's a similar option only he is using a more permanant cordon with spurs going down the wires instead across. So in methon one, the runners down the supports are from your renewal vines. In method two, the cordon is left (as long as it is continuing to procuce canes) and the canes fill gthe gaps between cordons. https://www.google.com/search?q=pruning+grapes+to+an+overhead+arbor&ie=&oe=
It looks like one of the many yellow mustards. How you control will depend upon if there is a crop or desirable plant around. Usually using a pre-emergent is part of the equation. There is corn gluten meal which is labeled for use around food. If course,, once it is germinated, you have to weed whack it or pull it. It looks closest to Rape.