If you are inspired to harvest knotweed by my last post, please find a patch that has not been poisoned!  Knotweed is very resistant to pesticides – it cleans up toxicity and pollution, after all – and a healthy patch may be growing where Roundup was sprayed.   The stems may contain some of the poison even though the plant is apparently not affected.

            Here are three indicators that your knotweed is safe.

            You know, because you live there or someone tells you, that poison has not been applied.

            Other plants that would die from pesticide are growing next to the knotweed.  I harvested some from a roadside where trillium is also growing.  Trilliums would not have survived a dose of pesticide.

            Cut the sprouts near water.  It is illegal to apply Roundup near water without a permit.  That is no guarantee, but it makes it more likely that knotweed growing near a pond or stream has been left alone.