 Maybe it goes for three or four years before it happens again. And I've seen other cases where they apply it maybe two or three times. So I would try it just once. Hopefully you're going to notice some improvement. If you start seeing it again the next growing season, I would look at applying it again. Usually if you don't see something within two or three weeks of that application right around the base of the tree, I would look at maybe doing a second application.