replanted 1/2 acre of natives after two complete growing seasons of spraying everything green that showed up. Lo and behold...the Sweet Coneflower that was one of the more villainous plants that caused me to start over after eight years is everywhere. It appears that either the seedbank from before was huge or the rhizomes remained dormant? Roundup resistant? Anyone else have this problem? Right now I'm hand pulling each plant..and there are thousands of them...if I can't get a handle on it I may have to start for the third time but then again I wouldn't know what to do about this stuff...wife not happy about the $1000+ in seeds so far and climbing...zone 5a. Very rich soil...when I removed them three years ago in the fall they were over seven feet tall...shaded out everything.