On June 12, 2024 researcher and practitioner Brian Colleran and Élisabeth Groeneveld shared their perspectives on managing invasive knotweeds (primarily Itadori knotweed, Reynoutria japonica) in a changing climate and answered questions from the audience. They focused on shifts in hydrological regimes towards more frequent and severe storm events in response to climate change, positive feedback loops may develop between existing knotweed populations, sudden riverbank failure, and increased flood-related damage. Mindful action to control these plants is therefore a climate resiliency opportunity.

Webinar

Brian Colleran presents on a recent publication that brings together the state of the science that links this group of invsive plants with a poorly understood impact of their presence on roadways and waterways.

Starting at 9:29

Itadori knotweed (aka Japanese knotweed; Fallopia japonica var. japonica), which is an infamous invasive plant in Europe and North America that amplifies and exacerbates impacts of climate-change-enhanced flooding, has had major economic impacts. A field study in the United Kingdom found best results from a multiple-stage glyphosate-based treatment, although no mechanical (cutting, covering, excavation) or herbicide (soil spray, foliar spray, and stem injection) treatments eliminated the knotweed entirely after three years. As a chemical control oriented project, mechanical control methods alone and variations on combined herbicide/mechanical methods were not assessed with the same variety of permutations given to chemical control. Nevertheless, some treatment combinations appeared to be more effective than others.

RISCC Research Summary

Mar Williams presented on her undergraduate thesis work at the University of Vermont, examining how the state of knotweed infested soil influences efforts to bring back native riparian vegetation

Recording Begins at 3:03.30