How do I kill thistle?

Question

I cut the weed as close to the ground….I “dribble” a weed killer on the open cut stem…and yet it comes back.

Answer 1

Cut stem treatment is not as effective for thistle as spraying or painting the leafy tops for foliar absorption with a systemic herbicide.
You don't identify the type of thistle, describe the site, - pasture, lawn or planting beds or un-planted soil surface, and you don't state what herbicide you have been using.
To spray in a lawn area use an herbicide for broadleaf weed control like this: https://www.domyown.com/msds/SpeedZoneLawnWeedKillerConcentrate-SL_label.pdf
But the active ingredients will kill other broadleaf plants, so don't use near desirable plantings.

https://www.gardeningknowhow.com/plant-problems/weeds/canada-thistle-control.htm