I've typically not had a big issue with bull canes, but when I pruned this spring I realized that they were a real problem in my Oberlin Noir. About 2/3 of my vines had run huge bull canes, often more than 20 feet long. Aside from the pain of untangling and cutting them out of the 2-3 neighboring vines they had run through, they sucked the resources of the vines and those vines had a sub-optimal amount of growth to provide for this year's production spurs...they put most of their vigor into those bull canes. Any tips for controlling this in the future? Do you just watch for them by digging through the foliage and cut them off early?