Ya' know, when I moved from the coast to the east side of the Cascades I thought I'd probably get away from this stuff. Wrong, wrong! But fortunately it's not as bad out here. Got away from the blackberries, and the scotch broom, but picked up on knapweed and some other real winners. Guess we just can't win.
I used to put on cotton gloves soaked in Crossbow over latex gloves and then "shake hands" with all of those little twerps sticking up out of the ground cover.
The pvc pipe over the weed idea is interesting...