Incluye bibliografía

This publication contains the Proceedings of a symposium held at Northwest Scientific Association Fortieth Annual Meeting, Pullman, Wash., 14-15 Apr. 1967. Among the 28 contributions the following are of interest to plant pathologists. a. J. L. NEAL, J. M. TRAPPE, K. C. Lu & W. B. BOLLEN. Some ectotrophic mycor-rhizea of Alnus rubra (179-184, 7 fig.). Distinct, characteristic differences between the fungal symbionts of 2 mycorrhizal forms predominating on root systems of A. rubra were revealed by morphological studies. Their abundance and influence on the rhizosphere could affect the incidence of root disease. b. G. WALLIS. Resistance of Alnus rubra to infection by the root rot fungus Poria weirii (195). Failure of attempts to inoculate A. rubra roots with P. weirii and studies of excavated root systems indicated that alder is resistant to sustained infection by this pathogen. C. C. Y. LI, K. C. LU, J. M. TRAPPE & W. B. BOLLEN. Enzyme systems of Red Alder and Douglas-Fir in relation to infection by Poria weirii (241-250, 3 graphs, 1 table. 31 ref.). The secretion of phenoloxidases toy P. weirii, and the higher level of phenoloxidase activity in alder leaves than in Douglas fir (Pseudotsuga menziesii) leaves, suggests that the resistance of alder to the fungus may be due to the formation of fungitoxicants through the catalytic action of the phenoloxidases. Since P. weirii cannot reduce NO3, high NO3 levels in alder stands are unavailable to P. weirii but permit build-up of antagonist populations. d. J. D. ROGERS. Hypoxylon fuscum: A review of the fungus and its relationship with Alnus in the Northwest (251-258, 10 fig. 12 ref.). The morphology and development of H. fuscum and known aspects of its relationship to Alnus tenuifolia are discussed. Inglés