My old foreman told me to stop pruning so close to the collar, and I owe him an apology
Honestly I argued with him for 20 minutes in the truck back in March about it. He kept saying leave the branch collar alone because the tree seals itself off there, and I kept saying flush cuts look cleaner and the client wants it neat. I did it his way on a silver maple in town and flush cut a red oak two blocks over on the same job, and by August the maple cuts were closing over clean while the oak had rot starting on three of the four stubs. Now I want to know if anyone here has seen flush cuts actually work out long term, or is the collar rule just always right like he says. What do you all do when a homeowner wants that clean look?