I have the wicked sister to White Campion called Bladder Campion.
http://www.ppws.vt.edu/scott/weed_id/silvu.htm

It won't laugh at Glyphosate, Banvel, 2,4,D or several other potent herbicides, but none of those chemicals will kill it either. The new seedlings will die, but it is a long lived perennial and onced established the only thing I have found to get rid of it is a moldboard plow. Best advice is to clean the equipment that is used to cut it because the seed will hitch a ride where ever you take it.

Here it is in alfalfa and red clover.




Here is why it is so hard to kill. IMO


It has one hell of a root.


The deer around here won't eat it either