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The perfect stage of a species of Leptographium isolated from lesions on western white pine affected with pole blight has been described as Europhium trinacriforme and a method has been outlined for obtaining perithecia in culture. Studies on the sexuality of the fungus have revealed it to be heterothallic with two compatibility types. Cross-fertilization experiments revealed the presence of isolates which acted as either males, females or hermaphrodites. E. trinacriforme was isolated from 11 per cent of the lesions on western white pine affected with pole blight in the Interior region of British Columbia and from 84 per cent of the lesions on affected trees in the Coast region. The fungus was the only pathogenic organism isolated more than twice from lesions and it was shown to be capable of producing lesions similar in several respects to pole blight lesions. However, further data from isolation, inoculation, histological and radial growth studies have shown that pole blight lesions were not caused directly by E. trinacriforme. It is most likely that the fungus gained entrance to lesions already formed and occasionally extended them. / Science, Faculty of / Botany, Department of / Graduate

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004. / Thesis documentation sheet inserted. Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix .

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.

Phellinus weirianus (Aphyllophorales: Hymenochaetaceae) causes a white heartrot of living Juglans and is the major cause of decay in Arizona black walnut. Infection is caused by germinating basidiospores. Tissue isolates fruit in culture, but single basidiospore isolates do not. The growth of tissue and single-spore isolates is slow to very slow. Cultural morphology is quite variable even among single-spore isolates derived from a single, culturally produced basidiocarp. Single-spore isolates, presumed to be homokaryotic, are derived from uninucleate spores that germinate and develop hyphae with paired nuclei. Lack of fruiting in homokaryons suggests that P. weirianus is heterothallic. Tissue isolates derived from basidiocarps produced in nature are assumed to be heterokaryotic. Hyphae of tissue isolates have nuclei that are not paired and are more numerous than those in single-spore isolates. Interaction zones are formed in pairings of heterokaryons, pairings of homokaryons, and pairings of homokaryons with the parent heterokaryon. Homozygous matings do not form an interaction zone. Agar-block decay tests show that single-spore isolates exhibit no appreciable differences in decay capacity from tissue isolates. Phellinus weirianus readily decays woods of associated riparian species (Arizona alder, velvet ash, southwestern chokecherry, netleaf oak, and Arizona sycamore) in standard wood test blocks although it is not known on these hosts in nature.

Previous research on coarse woody debris (CWD) indicated that moisture content and initial heterotrophic colonization of decaying wood can affect the decomposition process. Six heterotrophic treatments were created to simulate the effects of physical penetration of the bark and wood and the transmission of ascomycetes versus basidiomycetes into CWD. In 1995, 360 Douglas-fir (Pseudotsuga menziesii) were randomly placed at five replicate sites in old-growth stands. Each site had 6 heterotrophic (HET) x 2 moisture combinations (TENT). One set of logs representing the treatment combinations was used for sampling respiration and another set was used to measure volume affected by insect gallery excavations and fungal rot and to determine decay rates. Respiration was sampled three times during the summer of 2001. The results indicated that the HET treatments were no longer affecting respiration rates. Analysis of the average of the three sampling periods revealed no TENT effect but examinations of the individual sampling dates suggests that tented logs might have higher respiration rates than non-tented logs as summer progresses. In the aggregate, the TENT treatment reduced moisture content from 45% to 36%, a 20 percent reduction in moisture levels. The HET and the TENT treatments did not affect decay rates. The mean density change for the logs was -0.072 g/cm�� �� 0.03 and the mean decay constant was 0.026 �� 0.011. The TENT treatment did affect heterotrophic activity. The mean volume of wood borer excavation and extent of brown rot was higher in the tented logs (256 cm��) than in the non-tented logs (59.9 cm��). There was also a statistically significant interaction between the HET and TENT treatments. The largest differences in volume affected by wood borers and fungal rot were found in treatments that injected ascomycetes into the experimental logs. In sum, there was limited evidence that the differences in moisture content caused by the TENT treatment affected the decomposition process but the HET treatments appear to not be directly influencing decomposition after six years. The findings suggest differences in the initial community composition of heterotrophs have a decreasing impact on the decomposition process as it progresses. / Graduation date: 2004

No description available.

No description available.

No description available.