Question
I have lots of little holes in the trunk of my lilac and I am told they are worms & I need to get rid of them.  I am in Ontario where pesticides are banned.  How can I get rid of them?

Answer
Dawn, the best deterrent for worms and other crawling insects is BT, otherwise known as Bacillus Thuringiensis. This product is organic and comes only in powder form. It is commonly sold under the names Dipel, Green Step, or MVP. If you cannot find it at your local garden center, you can purchase it online at either Planet Natural or Gardens Alive.

http://www.planetnatural.com/site/safer-dust.html
http://www.gardensalive.com/product.asp?pn=8797  

Another organic control that is effective against worms is diatomaceous earth. This product is comprised of crushed fossilized diatoms. Although it is broken down into a fine powder, the shavings are extremely abrasive to soft-bodied creatures, such as caterpillars, worms, and centipedes. When they crawl through the powder, their bodies absorb the substance through their exoskeleton, causing them to slowly die from dehydration. In short, the abrasive shavings result in very small cuts on the worm's body causing them to lose fluid and perish.

http://www.planetnatural.com/site/diatomaceous-earth.html

I hope this information helps. Good luck, and please write again if I can ever be of assistance.  

Regards,  

Mike