Always use chemicals. Pathway, which has a label identical to Tordon RTU but is cheaper, is one of several possible herbicides that can be used with girdling, says consulting forester Scott Brundage of Columbia, Mo. In tests he has performed, he found that even double girdling black walnut trees was not effective. Many are still alive after two years. Other species also have exhibited an amazing ability to overcome girdling. Many girdled trees have the top die, but produce several sprouts, observes Brundage.