Biology, Ecological Impacts, and Management of Japanese Knotweed (Polygonum cuspidatum syn. Fallopia japonica) in Nova Scotia

Abstract

Japanese knotweed is an invasive plant that grows in disturbed sites across Nova Scotia. This study recorded an average spring growth rate of 6cm per day until reaching a canopy height exceeding 2m in June. Knotweed stands contained on average 17 stems and 8.0kg of fresh biomass per m2. Leaf cover was significantly greater in knotweed patches versus grass and shrub habitats in riparian ecosystems. Plant diversity in knotweed patches was nil, yet invertebrate diversity and abundances were similar across habitats. Small mammal tracks were more abundant in knotweed than shrub patches, but not as much as grass plots. Two herbicides were applied at four different dates in 2011. The following year, Aminopyralid was ineffective while Imazapyr treatments successfully reduced knotweed biomass, density, height, and leaf cover. Imazapyr application is recommended at full growth (June) or flowering (August). This project provides new information on an invasive weed in eastern Canada.