• Kyodo

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A group of British scientists will fly to Japan in July as part of a pioneering British-American project to find a natural solution to a rampant superweed that is playing havoc in both countries, a spokesman for the project said.

The weed-control experts will be touring Honshu in an effort to find natural predators to the Japanese knotweed, which is pushing through concrete and tarmac, choking thousands of kilometers of river banks and invading homes.

Weed experts say Japanese knotweed, or Fallopia Japonica, can grow 3.6 meters in 12 weeks with roots reaching a depth of 5 meters.

“The idea is to work in collaboration with Japanese experts and find the knotweed in its natural environment and see what’s on it,” said Richard Shaw, a member of British nonprofit organization CABI Bioscience who is leading the survey in Japan.

The British weed-control experts say they hope to identify the beetles and fungi that control the growth of the weed in Japan and eventually bring them back to Britain for trials in quarantine before releasing them into the environment.

Japanese knotweed was first introduced to Britain as an ornamental plant in the 19th century by a Dutch traveler and has since spread nationwide.

The weed is said to be particularly strong in southern England and some parts of the United States, particularly the East Coast and the Pacific Northwest.

Shaw said the survey team will spend two weeks in Japan, going to as many places as possible, particularly areas that are similar to the British climate.

He said any of the natural knotweed predators found in Japan would have to be tested in quarantine to make sure that they do not have an adverse reaction to indigenous crops and plants in Britain.

Weed control experts say using natural predators will mean businesses and local authorities will not have to spend money on reducing the knotweed by conventional means such as sprays.

“Japanese knotweed is the most pernicious weed in Britain, and biological control is recognized as the only cost-effective, long-term sustainable solution to this ever-growing problem,” Shaw said.

The project is coordinated by the Biological Control of Non-Indigenous Plant Species Program at Cornell University in New York. The U.S. Forest Service has provided the funding for the initiative so far.

U.S. and British scientists hope that money will be forthcoming from the British and U.S. governments as the project develops.