Hi, I have 2 grapes plants planted to the left side of the shed 3 years ago. This summer is the first time we got grapes. The plant started with loads of flower clusters and little grapes, and then the black rot came and wiped out most of the fruits. I managed to save a couple but cutting all the affected leaves and fruits.

As you see from the picture, the vines are out of control. We tried to train it up the roof of the shed, with minimal success. The weight of the leaves and fruits have the tendency to pull it down and block the door.

It is obvious we have to do something. How harsh should I prune back? When to prune? And what can I do to prevent black rot again? Any suggestions on how to manage the huge vines?

we considered building a grape trellis to the left of the shed, but it seems to do a lot of work.

thanks in advance for your expert advice.