Twenty populations of Bursaphelenchus mucrunatus collected from China, Japan, Canada, Korea, France and Norway were tested for pathgenicity to 2-year-old seedling of Pinus thunbergii. The populations were divided into three groups according to the pathogenicity. The strongest pathogenicity was observed in BmFr, BmCGHH, BmCFJ2 and BmFJ3. Their mortality rates was more than 85% and RHS index was over 100. The second group included BmCZZ, BmCHN, BmCWY1, BmCWY2, BmCWY4, BmCNJ, BmCSC1, BmCSC2, BmCGHP, BmCJX, BmCYY and BmCan, which had strong potential pathogenicity. The third group included BmJan, BmK1, BmK2 and BmH which were zero both in mortality rate and RHS index. The duration of life of black pine seedling was the shortest with BmFr population inoculation. The result of treatment with PEG and drought after inoculation with B. mucronatus indicated that drought-stress conditin could significantly increase mortality rate of the seedlings.
The objective of this study was to determine the pathogenicity of Bursapelenchus xylophilus isolates from China, Japan and Canada to 4-year black pine (Pinus thunbergii) and masson pine (Pinus massoniana) seedling. The results showed that their pathogenicity diferentiated distinctly. The mortality of black pine ranged from 0 to 87.5%, and the RHS index ranged from 0 to 110. The pathogenicity of Chinese nematode populations was greater than that of Japan and Canada. The pathogenicity of BxCN3, BxCSC and BxCZD was stronger, with mortality 87.5% and the RHS index exceeding 90. In the 6 isolates whose dead rates were 87.5%, the population of BxCN3 from Nanjing had the shortest death time, 38 days. In all of the tested populatios, the dead process of population BxCZD from Zhejiang was shortest, 14 days in black pine. The results of detrermination in P. massoniana indicated that 4-year seedlings resisted P. xylophilus, with only two seedlings died in this experiment. In this study, incubating carrier with non-symptom was found in P. thunbergii seedlings inoculated with pine wood nematode. It is important for incubaton of nematodes of the spread of the nematode.
