1993 Volume 59 Issue 6 Pages 666-672
Bursaphelenchus xylophilus was inoculated into the branch of wilt-resistant Pines taeda and P. strobus, and susceptible P. thunbergii. Ethanol-extractives from the inoculated branches were investigated for the presence of unique resistance chemicals. Accumulation of antifungal substances were observed both in the cortex/phloem and xylem of P. strobes one week after inoculation. Their activity was maintained during the experiment. Pinosylvin, pinosylvin monomethylether, pinobanksin and pinocembrin were identified among the inhibitory substances extracted from the P. strobes xylem. These substances are thought to immobilize B. xylophilus. Only slight inhibitory activity to the fungus but not to the nematode was detectable in P. taeda and P. thunbergii 5 weeks after inoculation. This suggests that ethanol-soluble inhibitory substances are produced in the resistance responses of inoculated branches of P. strobes against B. xylophilus infection, but not of P. taeda.
