Richard Shaw
Friday, October 17, 2008 - 2:00-2:30
Japanese knotweed (Fallopia japonica) has become a serious environmental and economic weed across the world. Introduced to Europe in the mid 19th Century and subsequently taken to North America in the 1870s, it is now present in 40 US States, listed as invasive in 12, and is recorded from, and considered invasive in, 8 Canadian Provinces. Japanese knotweed as well as the closely-related giant knotweed, F. sachalinensis, and their hybrid Fallopia x bohemica, are highly adaptable, rapidly regenerating, and persistent rhizomatous plants which have proved increasingly difficult to control mechanically and physically and are continuing to spread. A pioneering biocontrol project began for the UK in 2003 but from the outset North American funders were involved in ensuring the research was for a broader benefit. The resulting research has involved repeated surveys across knotweeds’ native range in Japan and has included collaborative studies of natural enemies by our teams in the UK, Japan, USA and Canada. This revealed over 200 associated arthropod and fungal natural enemies, some of which have been selected for extensive safety testing. This paper summarises the findings of the project so far, dealing with those potential agents of most interest to North America with particular reference to the prioritised psyllid, Aphalara itadori and a highly damaging Mycosphaerella leafspot. Whilst these agents are proving to be very promising for the UK, more work is required if this sustainable approach is to be taken to manage one of the most problematic weeds in North America.
Keywords: JAPANESE KNOTWEED, BIOCONTROL, APHALARA ITADORI, MYCOSPHAERELLA