Used to top all my client's oaks in July until that one in Austin split right down the middle during a storm
Started doing structural pruning in late winter instead after I saw the crack run 15 feet from a bad cut, anyone else dealt with a topping fail that changed your whole approach?
Late summer topping has ALWAYS worked fine for me and I've been doing it for 22 years. That oak split was probably already weak or planted wrong to begin with, not the pruning. Switching to winter pruning just means you're dealing with more decay and slower healing since the tree can't respond right away.