last spring, as an experiment I cut off the tops of the emerging Japanese knott weed in the lane behind my house, then filled the hollow stalks with a heavy duty weed killer. The treated stalks never grew any taller and appeared very shriveled and limp. I've been out several times in the past few weeks to see if this years weeds have started emerging. I've been unable to find any yet although the other side of the fence the weeds are about a foot high. Comments Please