Mortality of Scots pine following inoculation with the pinewood nematode, Bursaphelenchus xylophilus

Thirteen-year-old Pinus sylvestris in SE Iowa were inoculated with Bursaphelenchus xylophilus in the main bole of the tree or in the branches. Half of the trees were selected at random and destrictively sampled 18 wk after treatment. The remaining trees were harvested 50 wk after treatment. Eighteen weeks after inoculation, 10 of the 20 branch-inoculated and 10 of the 20 stem-inoculated trees were dead or dying. Fifty weeks after inoculation, 6 of each of the remaining 10 branch- and stem-inoculated trees were dead or dying. An average of 224.7 nematodes/g were extracted from samples collected from inoculated branches. Numbers of nematodes and proportions of samples with nematodes declined from 18 to 50 wk. Also, B. xylophilus was recovered from stem samples collected from 15 of the 20 branch-inoculated trees. An average of 184.7 nematodes/g were recovered from samples collected at 1 m intervals from stem-inoculated trees. -from Authors