We had to control it in the same way as Bostedo. It was still coming up 7 years later and then we moved (not because of the plant) :-)

Yeah that's unfortunate. Trumpet Vine doesn't die from Roundup. You pull it and it comes back from the roots.

I have a trumpet vine in a pot that part of me wants to plant in the ground, but i know better. I dont mind prunning and picking aggressive plants. I have grape, morning glory and passion vines that volunteer everywhere. I kinda like them for this aspect. Nutsedge is my only true enemy plant.

Nutsedge is my only true enemy plant.

The new halosulfuron-methyl nutsedge herbicides are pretty remarkable. We cleared all of ours within two treatments (possibly a third in a spot or two?). Unfortunately it doesn't phase campsis radicans.

Quarzon if it's Madame Galen, Madame Rosy or Balboa Sunset then youll be fine. They'll grow like crazy but they won't invade your beds with root sprouts

Ok, follow-up question - on the floral tubes, is a 3" one an ok size? Found a pack of 100 on amazon for about $15 and might as well get that many, cuz I fear I'm going to need them!

That's the size we use. Works well for almost all fresh/new growth that comes up from the roots or stump. A thirsty vine can empty one in a day, so check for refills the first couple days you put them out. They can be removed once the vine stops "drinking" - though I usually leave them on for another day or so.

Ok, so we put the vine stumps into the floral tubes with the ground-clear in them....NONE of them are drinking...it's been about 1 week and they're still mostly full - help please!

Sorry to hear you're having trouble. Here are a few things to check:

1. Confirm the cut end of stems are staying submerged in the fluid after positioning the tubes (or strong winds). We try to stick the tubes upright in the ground and cut the vine to reach them without kinking where possible. We do leave them hanging where this won't work, but this makes it easier for wind and gravity to pull the tubes far enough off the vines to move the cut ends out of the herbicide.
2. The usual recommendation is to use brush grade herbicide undiluted straight out of the bottle. But it is a bit thick, so might try thinning it a little with water. We usually do this and it seems to improve the uptake flow.
3. Seems Ground Clear should work as well this way as straight glyphosate. But am no expert/chemist; so suppose the addition of imazapyr as a soil sterilizer might be shutting down absorbtion too quickly through the cut stem. Might see if you get better results with a generic glyphosate-only (or Triclopyr) brush/poison ivy herbicide.

Bless you - we're going to try the additional methods and see what happens! Wishing us the best trumpet vine eradication ever!