Question
QUESTION: I live in Colorado and have had the basic lilac bushes in my back yard now for 10 years.  But one of them in the corner of the back yard now is having a problem.  The leaves are curling up and getting "crunchy".  The whole bush looks sick and droopy.
This has happened over the past 5 days.
How do I treat this before the bush dies?  The other bushes are fine, so far.

ANSWER: Dear RoseMary, This is a pretty tough question, so bear with me.   There are several things that could be wrong with your lilac, but the main suspects are dieback, verticillum wilt, bacterial leaf spot, or anthracnose.  It is hard to know for certain which of these are affecting your lilac, and the treatments are different, and even upon close examination it may be difficult or impossible to diagnose; so let's try to make a plan that will encompass all of these if possible.  The dieback is just what it sounds like; the branches will start to die back, but typically this disease is more localized and doesn't cover the whole bush.  The treatment for this would be to cut back the diseased branches, sterilizing between cuts, and spray with a copper-based fungicide (Bordeaux mix or Soap Shield).  Then the verticillum wilt will cause the entire tree to collapse over a very short period.  It doesn't often affect undisturbed stands, but it is certainly possible in this case.  Interestingly, there are not clear controls for this disease; and if this is the culprit, the bush may recover, or it might not, but it is generally not recommended to remove the bush immediately, but rather to wait and see if it grows better next year.  Then you have the bacterial leaf spot and anthracnose which might be controlled by NEEM.  So anyway, here is my recommendation.  I am assuming that you have ruled out drought or lack of water as to the cause.  In that case, you should clean up any dead leaves or litter in the area, cut and sterilize any definitely dead branches, and then you could spray the bush weekly with a mixture spray of NEEM and Bordeaux mix, and see if the bush begins to recover.  I strongly suspect that the lilac has died, but if there is a chance that it could recover I would give it every opportunity to do so.  I apologize that your question is such a complicated and inexact one, but please write back if I can offer you any additional assistance.  Good luck, Melissa

---------- FOLLOW-UP ----------

QUESTION: I have another question for you regarding the same lilac bush.  After 10 years, the owner of the house next door to me has landscaped their back yard with sod - it has never been landscaped before.  My lilac bush is right up next to the 6 foot fence that separates our back yards.  With new sod one has to water the new sod 3 times a day and everyday for at least 3 weeks.  I read in an article that lilac bushes do not like to have "their feet wet".  If this is the problem with my bush, would it have the same symptoms that it currently is showing, do you know?  Thank you!

Answer
Dear RoseMary, Wow!  That would definitely mess things up.  Now while overwatering the lilac can easily kill it, I don't think it would look dead so quickly.  So while the water increase has probably started this problem, the actual culprit would probably be a fungus. Either way it makes no difference, as it is just one of the many reasons why certain plants should never be overwatered: they aren't able to deal with the increase in soil fungus and bacteria, and the roots are unable to breathe in a saturated soil.  Now about your neighbors:  I have checked with numerous authorities and NO ONE suggests watering new sod three times a day.  The most I saw suggested was twice a day for 15 minutes for the first week, then daily for another two weeks, then down to probably every other day for a few weeks more.  If they do put that much water in the lawn, they will likely need to replace it.  The signs of drowned lawn are very similar to that of an underwatered lawn: yellowing and curling and inability to grow roots.  If you could add drains to the area near the lilac it might help some, but they must be seriously overwatering if your lilac died so quickly.  I wish I had better news for you, but please write back if you have additional questions.  Good luck, Melissa