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The nuclear behavior, vegetative incompatibility, and induction of basidiocarp formation and basidiospore germination of Inonotus andersonii was investigated. Safranin O-KOH and Hematoxylin stains were used to determine the number of nuclei in basidiospores, vegetative hyphae, and basidiocarp tissue. Both uni- and binucleate basidiospores were found in the tubes of basidiocarp tissue. The nuclei in the hyphal cells of presumptive heterokaryons typically numbered some multiple of two per cell which suggests that division is conjugate. Subhymenial hyphae and immature basidia were often uninucleate but tramal hyphae were multinucleate. Antagonistic hyphal interactions developed between different vegetative isolates on both 2% MEA and oakwood test blocks. Self-crosses were compatible. Basidiocarps formed in 12 wk on 2% MEA medium containing ground oakwood and wheat. Most attempts to induce spore germination failed. However, basidiospores obtained at the end of this study from actively sporulating basidiocarps germinated on 2% MEA.

The sudden oak death pathogen, Phytophthora ramorum, is present in southwestern Oregon, and while an eradication effort is underway, the potential impact of the polyphagous pathogen on surrounding vegetation is unknown. Plant communities in the area are substantially different from those affected in California, although tanoak (Lithocarpus densiflorus), evergreen huckleberry (Vaccinium ovatum) and Pacific rhododendron (Rhododendron macrophyllum) are hosts found in both areas. Other species are likely to be susceptible to the pathogen. Detached leaf and whole plant assays were used to test species commonly associated with tanoak, as well as three rare or endemic ericaceous species of the western Siskiyou Mountains and their associated taxa. Leaves and plants were challenged with zoospore suspensions that were capable of generating symptoms in the known hosts tanoak and evergreen huckleberry. Most (78%) of the previously unchallenged species developed necrotic lesions in detached leaf assays although severity (% leaf area necrotic) was variable. All three of the ericaceous species of conservation concern: Arctostaphylos hispidula, Kalmiopsis leachiana, and Leucothoe davisiae were susceptible in detached leaf assays. Factors important in determining whether or not these species will become infected in their native habitat are discussed. / Graduation date: 2004

The effects of gypsy moth defoliation on acorn production (the seed source for oak regeneration), and the forest floor regeneration environment were investigated. Parameters measured included: acorn quantity, weight, development, and viability; litterfall; and forest floor depth and biomass. Nineteen plots in north-central Virginia and western Maryland on which trees suffered heavy, moderate, or no defoliation were monitored over a two-year period. / Master of Science