Pathogenicity to western larch (Larix occidentalis) of two fungi, Ophiostoma pseudotsugae and Leptographium abietinum, associated with the Douglas fir beetle (Coleoptera: Scolytidae)
1 Pole-sized, live western larch Larix occidentalis Nutt. were mass-inoculated with Ophiostoma pseudotsugae (Romb.) von Arx or Leptographium abietinum (Peck) Wingf., two blue-stain fungi associated with the Douglas fir beetle Dendroctonus pseudotsugae Hopkins, to assess their pathogenicity.
2 Inoculation with O. pseudotsugae resulted in significantly greater percentages of necrotic phloem compared with L. abietinum inoculations.
3 The percentage of occluded sapwood was significantly greater after L. abietinum inoculations compared with O. pseudotsugae inoculations.
4 Within the inoculation band, all trees had more than 60% functional sapwood 4 months after treatment.
5 The results suggest that western larch can successfully limit colonization by O. pseudotsugae and L. abietinum.
6 The inability of the fungi to thrive in live western larch may be a factor in the consistent failure of Douglas fir beetle broods in this host tree species.
Document Type: Research Article
Affiliations: Department of Forest Science, Oregon State University, 321 Richardson Hall, Corvallis, Oregon, 97331-5752, U.S.A.
Publication date: August 1, 1999