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Hazards associated with different forest pest pathways and their economic impacts. Dr. Eric Allen, moderator An excellent set of contributed papers stimulated some discussion about pathways of exotic organisms. Joe Cavey (USA) identified the danger of how limited knowledge about a pest can colour our ideas of what pathways are facilitating its movement. For example, Chlorophorus annularis has been associated with several plant species other than bamboo but whether or not they are damaging to these plants is uncertain. Yuan Decheng (China) clarified that Chinese experts recognize bamboo as the primary host for larval stages; that other hosts serve as food plants. Concerns of wood chips as a pathway for insects raised in the paper by Magnusson et al. were questioned by Eric Allen (Canada) who cited studies that have found chipping to be an effective phytosanitary control for some insect species. Dave Dwinell (USA) agreed citing several examples. Christer Magnusson (Norway) replied that even a rare occurrence of an insect surviving the chipping process could result in an introduction. Rona Sturrock (Canada) commented that wood chips would not be an effective pathway for the root disease organism Phellinus weirii as suggested by Magnusson et al.; that fungi growing in chips would lack inoculum potential to survive and infect. Walt Thies (USA) pointed out the difference in spread potential between other fungal organisms such as Endothia parasitica and Heterobasidion annosum, both spread long distance by spores, and and P. weirii which spreads primarily by root to root contact. Ed Setcliff (Canada) suggested that P. weirii might be restricted in it's establishment potential by ecological or environmental constraints. Setcliff concluded the discussion by raising the issue of genetically-modified organisms and the problems that they may pose as "exotics".
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