the smallest splits. The slightest opening can be enough for the plant to grow back. Soil steam sterilization involves injecting steam into contaminated soil in order to kill subterranean plant parts. Trials in Haida Gwaii, British Columbia, using sea water sprayed on the foliage, have not demonstrated promising results. Biological Research has been carried out on a Mycosphaerella leaf spot fungus, which devastates knotweed in its native Japan. This research has been relatively slow due to the complex life cycle of the fungus. Following earlier studies, imported Japanese knotweed psyllid insects Aphalara itadori, whose only food source is Japanese knotweed, were released at a number of sites in Britain in a study running from 1 April 2010 to 31 March 2014. In 2012, results suggested that establishment and population growth were likely, after the insects overwintered successfully. In 2020 Amsterdam imported and released 5,000 Japanese Aphalara itadori leaf fleas, exempting them from a strict ban on the introduction of alien species, as one of the measures to contain the knotweed. The psyllids suck up sap from the plant, potentially killing young shoots and slowing or even stopping growth. It was hoped that the psyllid would hibernate over winter and establish themselves in 2021. Anecdotal reports of effective control describe the use of goats to eat the plant parts above ground followed by the use of pigs to root out and eat the underground parts of the plant. Impact of the plant outside its area of origin New Zealand Japanese knotweed is classed as an unwanted organism in New Zealand and is established in some parts of the country. Europe European adventurer Philipp Franz von Siebold transported Japanese knotweed from a Japanese volcano to Leiden in the Netherlands. By 1850, a specimen from this plant was donated by Von Siebold to the Royal Botanic Gardens, Kew. It was favoured by gardeners because it looked like bamboo and grew everywhere. Ann Conolly provided the first authoritative work on the history and distribution of the plant in the UK and Europe in the 1970s. According to The Daily Telegraph, the weed has travelled rapidly, aided by rail and water networks. In the UK, Japanese knotweed is a single female clone. However, it is able to readily hybridise with related species. In the UK, Japanese knotweed is established in the wild in many parts of the country and creates problems due to the impact