Fallopia japonica -
Japanese Knotweed
This fast-growing invasive plant is an
import that has escaped from gardens and is now crowding out many hedgerow and riverside
plants. Japanese knotweed spreads via its root system. In spring it shoots up rapidly, but
the Environment Agency advice leaflet suggests that it can be controlled by regular
cutting. (Here at Fishing in Wales we are not convinced that cutting will do
anything more than result in fragments taking root; spraying with a suitable herbicide is
our first choice of control mechanism.)
The main problem with alien weeds is that they were brought to Britain
without any of their natural predators. Recently, scientists have been experimenting with
biological control techniques. Beetles, caterpillars and 'rust' fungi may be the
answer, say scientists at CABI Biosciences, an inter-governmental biological research
organisation.
Left unchecked, Japanese knotweed soon reaches head height; its roots can
go down five metres into the ground. The plant flowers from August to October before dying
back to leave brittle hollow stems that stand throughout the winter.
Wildflowers of Wales
This wildflower is one of many dozens that are featured in the First Nature Guide to the
Wonderful Wildflowers of Wales, Volume 4 - Watersides and Wetlands.
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