Long-term survival of Bursaphelenchus xylophilus in a Pinus sylvestris plantation
Field inoculation studies have been carried out in Vermont (US). The aim was to assess the long term survival of Bursaphelenchus xylophilus (EPPO A1 quarantine pest) on Pinus sylvestris, in an established plantation of 20-year old trees. During summer 1987, 100 P. sylvestris, apparently healthy, were inoculated with the nematode (P. sylvestris isolate of B. xylophilus from Vermont). Inoculated trees were then periodically observed and sampled (or harvested) for the nematode up to the end of 1993. B. xylophilus was still present in living, healthy looking pines six years after inoculation. The nematode has been found in 20 % of the inoculated trees, of which 68 % were still living trees at the time of the first positive extraction. The authors concluded that the trees may contain low numbers of B. xylophilus in living and apparently healthy trees. They felt that this may be of concern to European forests: because if the nematode was introduced it could survive without being suspected for several years especially under cool climates, but could increase its population under certain conditions (e.g. dry and hot summers, stress due to timber operations) and induce tree mortality.
Sources
Halik, S.; Bergdahl, D.R. (1994) Long-term survival of Bursaphelenchus xylophilus in an established plantation.
European Journal of Forest Pathology, 24 (6-5)