The Warren Conservation Commission began an effort to control Japanese Knotweed in 2019.  Since that time we have learned a tremendous amount about the species as well as effective control measures that can be employed to eradicate knotweed on a site-by-site basis.  Our focus has been on the upper reaches of the Mad River watershed in Warren and with the recent inclusion of sites on the Mad River in Granville and Lincoln.  

Knotweed is among many plant species that can regrow out of small root pieces. It prefers riparian environments, or river ecosystems. We’ve found that it can be transported among plant matter and debris in gravel trucks, and populate in almost all conditions. Construction of any kind that requires dirt and gravel to be brought into a site can result in a knotweed contaminated site. From road ways, house foundations, new telephone pole holes, buried propane tanks, leach field and mound system for septic tanks, all these can create a new knotweed site. Japanese knotweed are all female clones and do not produce a viable seed, rather, they multiply rapidly through lateral roots called rhizomes.

While depositing gravel appears to be a primary way people are spreading knotweed to new areas (we see it in the mountains and plateaus), it also spreads quite well on its own- usually through root pieces breaking off and traveling down the river.

Starting in 2020, the town of Warren began employing interns to maintain the knotweed sites, develop new sites and analyze the efficacy of the project. The Knotweed project also relies on volunteers and community days to help pull the knotweed!