I have always kept Semi Dwarf apple trees to a low height , say 12 t0 15 ft high so I can manage them in my yard for more ease with pruning and spraying. I have some trees out in my fields more for the wildlife to feed on and some are getting quite high. How high will a semi dwarf tree get? How do you prune up so high.? with an extra tall step ladder?. I have an extending pole saw and pruner but it is still very difficult to thin branches up high. I possibly try to prune too much out.