Biological Control and Japanese Knotweed II

It has been announced that Dr Dick Shaw and his team at CABI hope to go field trials in an attempt to use a jumping plant louse (a psyllid) as a vector to introduce a leaf spot pathogen (mycosphaerella) to the masses of highly damaging Japanese knotweed in the UK. I can certainly appreciate the importance of trying to deal with this alien plant (Swansea is Japanese knotweed central) which was introduced as an alien species by gardeners who thought it was rather attractive. The hope is (and many laboratory tests appear to have been carried out to establish this over some 7 years) that both the vector and the disease agent are highly host specific and will simply die out when the host plant is eradicated. The results of their tests are available on the DEFRA web site for public consultation ( http://www.defra.gov.uk/wildlife-countryside/wildlife-manage/non-native/knotweed.htm). I personally retain some reservations about the whole process (and have been contacted by both local newspapers and radio on this topic). Less than 50% of biological control attempts have the desired effects and some attempts (e.g. the Cane toad in Australia and the mongoose in Hawaii) have led to environmental disasters that persist to today. In deed, psyllids are major problems for Eucalyptus trees in many parts of the world and you can't test for every eventuality when the agents go 'wild' over what might be quite an extended period. Japanese knotweed is a particular problem as biological control tends to work better when it is directed to the reproductive stages of problem plants but this weed can propagate itself without sex via tiny bits of root that remain in the soil (only very high temperatures will destroy them). The Western Mail carried a story on this (http://www.walesonline.co.uk/news/wales-news/2008/05/08/scientists-want-to-introduce-alien-louse-to-kill-japanese-knotweed-91466-20877161/) and I raised some of my concerns in a radio programme (http://www.walesonline.co.uk/news/wales-news/2009/07/24/japanese-knotweed-out-of-control-91466-24228325/).