I have several Black Oak trees, some refer to them as Post Oaks, I'm not sure of true name. They are scraggly looking trees with lots of dead limbs and not much shape. When thinning. if I have a choice between a Red Oak, White Oak or Hickory, I'll cut the Black Oak. But I have several that I have to keep. When is the best time to trim and/or top a Black Oak? I have read some comments (in this forum) against topping. Would topping a Black Oak help the shape? Is there a rule of thumb or guidelines for thinning, distance between trees, etc.? Is there a best time for thinning?