Question
Our lilac bush has cream color dotes on all of the stems/branches and most of the plant is dead to the ground except the outside branches.  Can you help me know what might be happening and could it be something that would spread to the neighboring bushes. Thank you

Answer
The plant may very well be infested with scale insects.  These bugs will be oval in shape and do not move while feeding.  You can scrape them off with your fingernail.  These bugs can kill the plant if not treated. I would treat the plant with Bayer Advanced Tree and Shrub Insecticide.  This product is mixed with water and poured on the soil around the base of the plant.  It is taken up systemically and will kill the bugs within a week or so.  It also provides protection from reinfestation for up to a year.  I hope this fixes the problem.  Good Luck.