§ Mr. Ron Davies
To ask the Secretary of State for the Environment what information he has concerning the extent, environmental impact and rate of spread of Japanese knotweed; whether he is currently funding any relevant research; and whether he has any proposals to control its rate of spread.
§ Mr. Trippier
Japanese knotweed is regarded as a troublesome pest in much of Wales and parts of north-west and south-east England. I am advised that Welsh Water has conducted field trials on methods of controlling this species and that the Nature Conservancy Council takes steps to control it on sites important to wildlife.
The most effective chemical treatments are picloram and glyphosate—only glyphosate should be used on sites adjacent to water. Uprooting small plants and regular cutting or mowing also help to deter the plant's growth and spread over particular sites.