What is best way to kill/remove lilac suckers permanently?
We had several old lilacs which we cut down, intending to replace them with some other shrubs. However, we have at least 100 suckers growing where the older shrubs were, and would like to know the best way to remove these, hopefully permanently. We do understand that they may be difficult to get rid of.
Baltimore County Maryland
You have two options. You can exhaust the root system (which is storing lots of reserve energy for resprouting) by repeatedly cutting it back. This could take a couple of years, especially if you let new suckers leaf out and keep renewing the roots.
Or, you can spray with a systemic (gets into the system) herbicide that will travel down and kill the roots. An herbicide with the ingredients glyphosate or triclopyr (not both) should work. You do not need other herbicides mixed in. Fall is a good time to apply these as plants transport down to the roots this time of year in preparation for winter. Glyphosate is a total vegetation killer. Shield any desirable plants nearby. Target only the lilac suckers.