I have an 8 yr old lilac tree. I have never fed it. It usually does well with the leaves, but the last 3 years hardly no blooms. There are always lots of birds on the branches. This year, it is very slow in blooming with leaves. just very tiny buds. To look from a distance, it looks dead. I thought I would try to treat it or spray it. Not sure if the birds are causing the tree to be stunted. There are many dead branches. I have scratched the bark of the ones that do have a tiny bud and they are green.
Any suggestions on what to use (spray or a fertilizer stake? Please advise.