vine growing like crazy

[corinth]

I have several wine vines and several are several years old. Many have several bunches of grapes but there are several vines which have no fruit on them and are growing at a rapidly. Should I cut those back since they are growing four feet and growing. a few vines(pencil thickness) from the main trunk have fruit but also are growing rapidly but there is no fruit on these beyond the grapes some two feet or more beyond the grapes up to six feet. they do not appear to have a purpose so should I cut them back.

thank you,
corinth

 

[grapeman]

The rapidly growing vines can become too thick to fruit. That is the purpose of winter/spring pruning. Light needs to get to the forming buds at the point where the leaf petiole attaches to the shoot. If light gets to them, the resulting shoots will be fruitful, if not they get no fruit. Too late this year for a proper pruning, but thinning the vines out will allow fruit bud initiation for next year.

The shoots with fruit only normally have one to three clusters within the first section of the shoot growth. Beyond that they do not get fruit, but you need to leave some to all of that shoot so it can ripen the clusters later. Many people say it requires 12 to 17 leaves on that shoot to ripen the fruit.