Last November I pruned a lot of branches of a acer tree that was getting too tall, as it is close to the house. This summer, very many shoots grew form just below each cut branch. These new shoots grew about 36 inches long, from April to August, which surprised me. Now this November I have had to go up and cut off off these new shoots to stop the tree getting bigger again. How can I prevent thyis fast growth of so many new shoots, sometimes three from each cut?