MBR, THe main problem with all vine type plants like pumpkins and squash is an insect called the Vine Borer. They enter the vine near where it comes out of the ground and kill it. So I would not prune them. As far as the zuchinni, as with almost any vine type plant, pick them early. If they get big they are too tough. That goes for any type of squash, cucumbers and beans. Phil