Killing a Trumpet Vine

(Question)

I had planted a trumpet vine 2 years ago and then moved it to a new location last year. I noticed that the vine has popped up again in the original location and several feet away. I need to destroy this plant without destroying other plants around it. Can I use Roundup or something on the vine? If so, will the Roundup get into the soil and possibly kill my other plants. I have a beautiful Rising Sun Redbud planted this year that I definitely do not want to lose trying to kill the Trumpet Vine. Thanks so much for your assistance.

(Answer)

Trumpet vine (Campsis radicans) is a fast growing perennial vine.  While not classified as invasive, trumpet vine can be extremely aggressive.  Trumpet vine readily self-seeds, and suckers profusely from underground runners.  Long after you’ve removed any above ground plant material, these runners will continue to spread and sucker.   For this reason, Trumpet vine is notoriously difficult to control.

RoundUp (glyphosate) is a broad based herbicide that is absorbed by the leaves of plants and prevents the production of an enzyme necessary for survival. Glyphosate is readily bound by organic matter and clay in soils and so any residue from spraying leaves is typically not taken up by seeds, new shoots or into plant roots.   For this reason, glyphosate will not be particularly effective in eradicating your trumpet vine.   If you live in Ontario, it is important to note that glyphosate is a Class 9 pesticide which are banned for cosmetic use under the Pesticide Act.  Before you use any pesticides, you should check local regulations on their use in your area.

The only effective approach will be to diligently eradicate as many of the underground runners and suckers as you can.  Dig out any remnants of roots in the old site, and remove suckers and their runners as they appear.  Because the runners spread so effectively, it will be important to monitor not only the former site, but throughout the surrounding area.  Realistically, it may take two or three seasons before you are able to completely eradicate the plant.