I planted my laurel willow about 6 years ago from a small specimen. It has grown about a foot per year but last year had few leaves with a lot of brown spots. This year it has only developed leave at the tip of each branch. The leaves currentlylook healthy..there are just so few of them. I root watered before freeze last fall hoping it would help and we have had regular rain, so I haven't even watered potted plants much. Other closeby trees and shrubs are doing well. What could be causing this and how do I correct it?