Question
My lilac bushes are 30 years old and the last two years have developEd  curled twisted leaves and now the plant appears to be dying

Answer
Hi Nita,

If you are seeing curled and twisted leaves, this suggests two possible problems.  It could be that your plant is suffering from chemical injury.  You will have to investigate chemical use in the area to figure out if this is a possibility.  In most cases where I find chemical injury, people have used chemicals on their lawns or sidewalks for weed control.  Just because you aren't using them, your neighbor might be. Some herbicides are very stable and can volatilize and drift a few days after application.  So, just because it was calm when a person applied a chemical, sensitive plants can get drift injury after a while.

You will also want to make note if there are any pastures or roadsides nearby.  These areas may have been sprayed and could be a source of chemicals.  I have also had cases where people have used manure or compost around plants and had chemical injury develop.  Sometimes the herbicides do not break down during the compost process and the chemicals used on pastures can occasionally survive the digestive system.

If the problem is chemical injury, some plants will survive while others will be killed.  It simply depends on how large the dose of the chemical is.  I would recommend continuing to care for the plant by watering occasionally, especially during periods of drought.  In late winter or early spring, you should fertilize the plants with a fertilizer for trees and shrubs.

Otherwise, your symptoms sound like it could be a virus problem.  Some plant viruses can cause twisting and distortion of leaves.  Viruses do not usually kill their hosts, but just make them look bad.  Most viruses will make other symptoms including unusual yellowing or patterns.  There is cure for a plant virus.  If you suspect this may be the problem, you may want to contact your local county extension office and ask about testing.  In many states, there is a low fee for testing but it could be worth it if you are trying to figure out if this is the cause of the problem.  If you tell me where you are located, I  can help you find your county extension office.  Our you can simply do an internet search for "county extension office" and the county, state you live in.  

I hope this helps.  Let me know if you need anything else.