|I have a 4 year old lilac bush that has developed a severe split in the main trunk. Should it be repaired, and if so, how?|
|It's very difficult to repair a shrub or tree, though I have seen it done for valuable specimen trees. Your lilac is valuable to you, I know, but if the trunk is severely split below the main branches, you're better off starting over. If an nursery professional or arborist were able to bind it and get it to heal, it would always be a weak point in the trunk, prone to future damage or disease. Of course, it's always a good idea to get someone on site to assess the situation - it not be as damaged as I imagine!
If there are other buds or branches below the break, you can prune off the damaged portion and keep your lilac growing. Use a pruning saw to cut the trunk at a 45 degree angle within a 1/4" of a side shoot or bud.