Today sees an important milestone in a CABI project, led by Dr Dick Shaw. Defra gave the go-ahead to release an insect, a psyllid, to stop the spread of the non-native invasive plant, Japanese Knotweed. 

10 years ago a research project was undertaken by CABI to stop the spread of the non-native invasive plant, Japanese Knotweed. In 2001, a consortium of partners were brought together to form a project management board. The aim of the board was to oversee a scientific research programme, which examined the potential for biological or natural control of Japanese Knotweed in Great Britain.

Japanese Knotweed, otherwise known as Fallopia japonica, is listed by the World Conservation Union as one of the world’s 100 worst invasive species. It has an astonishing growth rate of up to 1 metre a month and can grow through tarmac, concrete and drains. Not only does it cost the UK economy over £150 million a year to control and clear, it also damages our natural environment by preventing other plants from growing, and destroying habitats for native species.


Wildlife Minister, Huw Irranca-Davies said: “This project is not only ground-breaking, it offers real hope that we can redress the balance. These tiny insects, which naturally prey on Japanese Knotweed, will help free local authorities and industry from the huge cost of treating and killing this devastating plant”.


The psyllid, also known as Aphalara itadori, is a predator of the plant in Japan and is indeed tiny, measuring only about 2 mm long. It is a true knotweed specialist that sucks the sap from the plant and despite its small size, is capable of causing significant damage to this target weed. Its use represents the first time this natural form of pest control has been implemented to combat the spread of a non-native invasive plant in Europe. Dr Dick Shaw, who spoke on BBC breakfast this morning, said “This is a great opportunity for the UK to benefit from a technique commonly used outside Europe. We have every reason to believe that this knotweed specialist can help limit the impacts of this harmful invasive weed safely and sustainably.”

Dr Matthew Cock, chief scientist for CABI, says of this release in Europe, “about time too”. In the Green Room of the BBC this week, Matthew sets out the case in favour of introducing natural predators against invasive species. He states that the concept of using biological control against a plant is far from new, and Europe has been lagging behind other regions that have had more challenging experiences with invasive non-native species.

CABI have carried out extensive research into the best way to combat Japanese Knotweed with the least impact on the environment. The psyllid was found on Knotweed growing wild in Japan and has now been tested in the UK on over 90 types of plants, focussing on closely related native species as well as important crops and ornamental species to ensure it does not attack other plants. If the first phase is successful, the psyllid will be released at further sites where it will continue to be monitored.

The earliest time at which release could be realised is Spring/Summer 2010. Release of the psyllid will be on a phased basis, with the initial release at two to three closely monitored sites in England.


CABI has a long history researching invasive species that affect agriculture and the environment to find biological ways of controlling them. But our role is now much broader than that: we advise on policy for invasive species management and we implement countrywide management plans.


This year also sees the launch of CABI’s Invasive Species Compendium, which unsurprisingly contains a detailed datasheet on Japanese Knotweed written by Dr Dick Shaw.

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