Comparison of the pine wood nematode, Bursaphelenchus xylophilus from pine and balsam fir

The pine wood nematode, Bursaphelenchus xylophilus was found on balsam fir in Minnesota and Wisconsin but was apparently not the primary cause of tree mortality. Unlike B. xylophilus from pine, adult females from balsam fir bad mucronate tails similar to those of B. mucronatus. However, B. xylophilus from balsam fir mated with B. xylophilus from pine and not with B. mucronatus. The balsam fir isolate of B. xylophilus was pathogenic on greenhouse grown balsam fir seedlings and did not kill Scots or red pine seedlings. The converse was true for a pine isolate of B. xylophilus from Minnesota which killed pine and not balsam fir seedlings. Pine and balsam fir isolates of B. xylophilus reproduced equally well on cultures of Botrytis cinera, but the balsam fir isolate reproduced minimally on cultures of Ceratocystis ips.