Hello

Sorry for the delayed response.

Trumpet vine can grow from seeds, parts of the vine, and pieces of root left behind. To eradicate it, paint herbicide on the growing leafy vines, covering all above ground parts as best as you can without spraying, dripping or allowing wind to drift the herbicide onto any of your desirable plants. Large woody vines can be treated by cutting the vine close to the ground and immediately painting full strength herbicide on the cut stump (within 1-5 minutes).

Triclopyr or glyphosate are the active ingredients to use on trumpet vine, Campsis radicans. These are non-selective herbicides, killing all plants which they contact. There are several products available and they are often labeled as brush killer type products.

After treatment, leave the treated vines in place at least two weeks to give the herbicide time to travel to the roots. If vines are very long, cut them back leaving a couple feet of vine with leaves to be treated.

You will have to monitor the area and continue to treat new sprouts for several seasons to exhaust the surviving roots and any seed that sprouts. Some success with suppressing new sprouts can be had by laying down weed blocker mats and covering those with mulch. This will not be 100% effective since any light getting through the cracks in the matting will allow sprouts to germinate. Check under your matts each season and treat any new vines.

Notes on the herbicides:

Always read the label and follow all precautions on any herbicide used.

Glyphosate works when plants are still actively growing. You get good control in the fall when temperatures are consistently above 50F.

Triclopyr will persist in the soil for up to several months, so it is not recommended for areas that you will be planting desirable vegetation in soon.

Please read the label on the product you use for time to wait before replanting in the area.

Reference

https://aquaplant.tamu.edu/management-options/how-to-control-trumpet-vine/