It crowds out native plant species
By growing in thick, dense bushes that can reach 3 meters tall, light cannot get through to the ground and native species are crowded out.
Riverbank erosion
Unlike many native riverbank plants, the Himalayan Balsam is an annual plant and so both the plant and its shallow roots die back over winter. This leaves large areas of riverbank without roots to hold the soil together causing riverbank erosion, particularly in high water conditions and during winter floods.