ABSTRACT
Control measures for Himalayan balsam are problematic. Some UK local wildlife trusts organize “balsam bashing” events to help control the plant. However in some circumstances, such efforts may cause more harm than good (Hejda and Pyšek 2006). Destroying riparian stands of Himalayan Balsam can open up the habitat for more aggressive invasive plants such as Japanese knotweed and aid in seed dispersal (by dropped seeds sticking to shoes). Riparian habitat is suboptimal for I. glandulifera. Spring or autumn flooding destroys seeds and plants. The best way to control the spread of riparian Himalayan Balsam may be to decrease eutrophication, so allowing the better-adapted local vegetation that gets outgrown by the balsam on watercourses with high nutrient loads to rebound naturally. For areas away from streams, the best option is to manually clear affected areas. In 2010, the UK government announced that it would allow a natural predator to be used to help control Himalayan balsam. The effectiveness and outcome of such action will be watched closely by all concerned with urban nature and the countryside.
