Hello. My grandmother has 2 mature lilac trees (white and purple) and they're at least 20 years old. She never planted them, she's always been adament they just "popped up" one day many years ago. But there her pride and joy. She really loves them. Anyway the problem is this. The trees are not flowering and are there has not been any green leaves on them for at least a year, possibly 2 years. The trees are in full sun and are located in the front garden. About a year ago we noticed some adolescents sitting on the garden wall by the trees and they thought it was funny snapping some of the branches off (I think it was the smaller branches) . I'm wondering if this could be related. There is one other thing, about 2 ft away from the lilac trees there is a fur tree which is in full bloom and is quite bushy and about 12ft + in height on the right side of the trees. This tree is roughly about 6-8 years old (could be older) and hasn't caused any problems for the lilac trees before but thought I would mention it. Does it sound like the trees are dead? How can I tell if they're dead? Is there anything I can do to try and save them? They look beautiful when in full bloom.