Question
Hello: we live in NJ and planted a 8ft. Lilac tree in November...it had good flowering and grew a bit but we now notice that it has brown coloring on its leaves and does not look healthy...what can we do?

Answer
Hi there: Sounds like an abiotic(environmental) problem.
Transplant shock,too much or to little water,poor planting hole.I doubt if last winter was a problem because we had a relatively warm winter here last year.
I would suggest a 3-4 inch covering of mulch (keep it 3-4 inches from trunk)and see what happens next year.You won't see much growth on a newly transplanted tree for a couple years.
Here is a link to a lilac disease. I doubt this is your problem but you can take a look.

http://plantclinic.cornell.edu/FactSheets/LilacBactBlight/lilacbactblight.htm

Hope this helps,Bill