@vossner, We fill the floral tube with herbicide, stick it into the soil/mulch near the plant we're trying to eliminate, arch the stem/vine to the tube, cut it off at a length that will reach the bottom of the tube without kinking, and then insert into the tube. We check the tube daily and refill as needed until it is no longer absorbing, which is usually within 3 or 4 days. Pretty sure I first saw this recommended elsewhere on GW, but couldn't find the original thread - someone please give/take credit if you know.

We buy the more concentrated "brush" herbicide which some say to use full strength. We mix with some water to lower the viscosity, but less than the label calls for. Photos show a tube being used on one of 4 or 5 campsis radicans vines that came up underneath a gaura plant last year. Normally the tube would be stuck in the ground behind the stone, but I left it out for the photos.

Second photo was three days later meaning it probably took in a little over a tube of herbicide before the vine stopped absorbing. The remaining healthy leaves were on a different vine that was subsequently killed the same way.

Tube doesn't have to be perfectly upright if the seal around the stem is tight. Might even work with the tube inverted on stiff stems if the seal is good enough. We've only used on new bamboo shoots while they were still flexible.