The Knotweed Patch was about 50 x 50 feet and 12 feet high. Now there's just a big dead spot.
Of course, it is not enough to kill an invasive species, if that is just replaced by another invasive species. Here we have Mugwort poised to take over, unless the Autumn Olive can do it first.
Although the larger-stemmed Japanese Knotweed plants have been killed, the smaller stemmed plants on the periphery could not be injected because the large injector needle splits the stem and the Round-Up just drains out. Follow-up is critical for these smaller plants, or they will take over in no time.