Just as the wisteria had become over-grown, so had the grape vine on the pergola. So much so that, like the wisteria, it was invading nearby trees and shrubs. It needed decisive action and now the pergola may be a nicer place to sit. Sadly I left it at least a month too late and the sap was rising so that I got dripped on as I worked- sorry grape-vine, I hope that you recover OK!