The state Supreme Court of South Dakota ruled this week that a couple can go ahead with their lawsuit against a neighbor that they say is causing their horse farm to be taken over by weeds. According to this article from Aberdeen News, the judge agreed that the neighboring landowner had "a duty to exercise ordinary care." The weed in question here is kochia (Kochia scoparia), which can be a major invasive on agricultural land, but is not regulated in South Dakota. The fact that the judge considered the neighbor negligent suggests that there is more to this story than is revealed in the article, so it's probably not time to start worrying about getting sued if an invasive plant pops up on your own property once in a while. Ironically, kochia is recommended by some as a drought-resistant forage crop.
Thanks to a member of the ALIENS-L listserver for posting a link to this story.