It would be useful if the reasons for designation as a noxious weed are given. Perhaps in some places, they are. In some cases, it is because the plant is poisonous to livestock. Being deadly to humans doesn't necessarily count, and it took me a while to get Conium maculatum (which has killed one child here) removed from a public garden. (The head gardener phoned the powers that be, who assured him it was not a noxious weed.) It continues to thrive throughout the region, and every year I give warnings to people who have it growing on their land. Some plants are prohibited because they are an alternate host of a disease that destroys an important crop. (Mahonia and Berberis/ wheat) though minor crops don't receive the same protection (pear/ juniper). Plants whose only crime is excessive propagation did not get added to the banned lists. Fairly recently (in the last 20 years or so), volunteers have been allowed to destroy plants like ivy, broom and blackberry in parks. Prior to this, no one was allowed to remove them, even though some people had sought permission. Diane Whitehead Victoria, British Columbia, Canada maritime zone 8, cool Mediterranean climate mild rainy winters, mild dry summers