Date of Award:
5-1982
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Biology
Committee Chair(s)
Michael A. Walsh
Committee
Michael A. Walsh
Committee
Sherm Thomson
Committee
Ray Brown
Committee
Mike Jenkins
Abstract
In the western regions of North America, mountain pine beetle, Dendroctonus ponderosae Hopk., infestations take a tremendous toll of pines , especially lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm.. Mass attack by the beetles is a devastating event for the trees. As well as girdling the tree, a massive inoculation of blue stain fungus "complex" (composed of several species of Ceratocystis, numerous yeasts and other mycelial fungi) is made beneath the bark. These fungi colonize and destroy the parenchyma tissue system of the host sapwood, primarily the ray parenchyma and resin duct epithelium.
A blue stain is produced in the sapwood as a consequence of destruction of the sapwood parenchyma. The stain develops inward through the sapwood, and the transpiration stream is cut off. As more and more sapwood is stained, foliar water stress begins to increase. Foliage however, remains green and apparently healthy for up to 10 months after inoculation. When spring bud break begins the year following beetle attack, terminal buds of blue-stained trees begin to expand, then abort. Soon after, the needles of these trees fade to a reddish brown color.
Transpiration stream disruption was not caused by penetration of tracheids by fungal hyphae; tyloses were not observed; nor was microconidial blockage of bordered pits seen. Though resin duct epithelium was eventually destroyed, little resin soaking was observed in the initial blue stained regions. Many bordered pits of tracheids in stained regions appeared to be aspirated, suggesting introduction of embolisms.
Checksum
4019cca4458492ec5dc651b6de77a19c
Recommended Citation
Ballard, Richard Grant, "The Pathogenicity of Blue-Stain Fungi on Lodgepole Pines Attacked by Mountain Pine Beetle" (1982). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 6411.
https://digitalcommons.usu.edu/etd/6411
Included in
Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .