Record Details
The relation of cover to the distribution of Armillaria mellea in a Ponderosa pine forest
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | The relation of cover to the distribution of Armillaria mellea in a Ponderosa pine forest |
| Names |
Adams, David Howard
(creator) Roth, Lewis F. (advisor) |
| Date Issued | 1972-04-28 (iso8601) |
| Note | Graduation date: 1972 |
| Abstract | Numerous isolates of Armillaria mellea were obtained within a 250 by 450 foot Study Area in a ponderosa pine plantation in central Oregon. These isolates were recovered from roots of armillaria-killed young-growth pine, from large stumps of the former pine overstory, including roots away from the stump proper, and from roots of living shrubs. Characteristic interactions between compatible and non-compatible mycelia in paired culture clearly distinguished group affiliations among the isolates. Three groups (A, B, and C), unequally distributed numerically among the hosts from which they were isolated, were recognized in the Study Area. Members of the same groups and of other groups were found among isolates from roots of shrubs and pine in plots surrounding the Study Area. Isolates of group A were recovered seven-eighths of a mile apart. Only members of groups A and B were recovered from armillaria-attacked young-growth pine, while C group members were predominately recovered from rhizomorphs on roots of living shrubs. Inoculation of potted conifer and shrub seedlings with A and C group isolates revealed the presence of physiological strains of A. mellea. Rhizomorphs were found on the roots and root crowns of all plant species tested, but only members of group A were pathogenic on conifer seedlings. Shrub seedlings were not killed by either A or C group members although rhizomorphs of members of both groups were in close physical contact with living root tissue. These results agree with the field occurrence of groups A and C in the Study Area. Roots of living and armillaria-attacked sapling pines were excavated in the Study Area. Infections of killing potential were found to occur only at the root crown; lesions on lateral roots were common, but did not contribute to the death of the trees examined. There was no evidence in this research of the fungal spread through root contact reported elsewhere in the literature. Armillaria attack stimulated the host to secrete large amounts of resin at the attack site. Attacks in the root crown region, which ultimately were lethal, caused excessive resin production. The fungus developed very slowly in host tissue during the period of resin secretion, but thereafter A. mellea quickly ramified the cambium of the now moribund or dead roots killing the tree. Cold-water extracts were made from foliage, roots, and litter of ponderosa pine and shrubs on Pringle Butte, and from soil under these plants. Extracts of foliage (1:40 and 1:61 dilution) stimulated mycelial growth, and rhizomorph production and elongation over that of the control. Extract dilutions of 1:168 and 1:1600 did not greatly stimulate fungal growth. Extracts of roots, litter, and soil had little effect on growth of A. mellea in culture. |
| Genre | Thesis/Dissertation |
| Topic | Forest ecology |
| Identifier | http://hdl.handle.net/1957/45740 |
