Well I've spent the spring and summer torturing my Knotweed patch. It turns out to be just about an acre in size and I have mowed and sprayed and mowed and sprayed the Knotweed over and over. I lost the exact count, but I know I've sprayed it at least 4 times this season. I'm afraid that I may be developing a Round-up ready strain of the stuff. I have been using 2 quarts of Power Max per 25 gallons of water, and it's not even putting a dent in the Knotweed. I've got to eradicate this stuff and reclaim this area. Any suggestions would be greatly appreciated.