UK: Airborne infantry to attack knotweed


One of the UK's high-profile, so called, invasive alien species Japanese Knotweed (Fallopia japonica) is soon to face its toughest challenge yet in the form of a tiny predatory insect.

Knotweed has become infamous for rampaging over the landscape, stifling the growth of native plants and causing damage to river banks. So tenacious is the plant, introduced as an ornamental in the 19th century, that it can even grow through roads, pavements and buildings.

After a string of failed global introductions this move was always going to be controversial. Is the right way to deal with an alien is to simply release another alien? But it seems, at least in the short term, it is. The proponents would argue that it is merely expanding the techniques of biological crop protection already employed by many farmers (where beneficial bugs are released to prey on harmful pests and diseases).

After years of consultation and research, that showed the chosen insect Aphalara itadori (also native to Japan) would not harm native plants and crops, the release will be trialed on two carefully controlled sites. If it all goes horribly wrong there will be a contingency supply of insecticide and herbicide on standby!

It's estimated the current eradication programme, which typically employs a glyphosate based herbicide, costs £150 million a year (total physical eradication was estimated at £1.5 billion in 2003), and despite this huge expense barely seems to have scratched the surface in troublesome areas.

Interactive map of Japanese Knotweed on the National Biodiversity Network

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