Nothing left but the suckers

During the heat wave, I spent a last few hours pulling up everything I could under the prune tree. All that’s left are the suckers growing around the tree. A fellow at work, who has some experience in these matters, suggested that after the shoots are cut down I should paint them with Round-up concentrate. I’ve also read of a product called Sucker Stopper RTU. I’ll have to look into that. I want the suckers dealt with before applying the corn gluten.