(Even the supposedly benign herbicide Round-up is being found to be much toxic to both plant and human life then previously understood, because of the adjuvants mixed in with the chemical to make it several times stronger...(http://www.naturalnews.com/025534.html) There are bio-control methods, other than digging out roots and rhizomes, etc. One feature of the most invasive plants is that they need strong sun-light to be aggressive. A farmer in Northern Thailand once showed me how he controlled a very invasive tall grass (Imperata sp.) with a cultivated vine. He cleared many small plots (2-3 square meters each) in the field to be re-claimed. In these mini-plots, he planted an annual viny black bean plant. Of course, he had to physically control the growth of grass in these mini-plots. But these vines would climb up over the surrounding grasses and cover them, not only reducing their aggressiveness, but eventually killing them too. Furthermore, he could harvest the beans and sell them at the local farmer's market. Has anybody tried a similar method for invasive species, like for example Himalayan Blackberry, in North America?