Pathogenicity of fungi isolated from Quercus suber in Catalonia (NE Spain)

Thirty-four fungal species isolated from cork oak (Quercus suber) in Catalonia (NE Spain) during 1992-95 were tested for pathogenicity either in stem, leaf or root inoculations. Eleven species were found to be pathogenic on stem: Biscogniauxia mediterranea, Botryosphaeria stevensii, Diatrype ci. stigma, Endothia gyrosa, Fusarium solani, Graphium sp., Ophiostoma quercus, Phomopsis sp., Phytophthora cinnamomi, Sporendocladia bactrospora and an unidentified Coelomycete. Three fungi showed pathogenic effects on leaves: Dendrophoma myriadea, Lembosia quercina and Phomopsis quercella. No clear pathogenic effects were detected in the root inoculation experiment. Trunk pathogens were differentiated into two groups according to the effects induced in the inoculated plants; B. stevensii, Phomopsis sp. and P. cinnamomi caused the death of the inoculated plants and induced the formation of large cankers and vascular necroses. The other pathogenic species also produced severe cankers and vascular lesions, but no significant mortality was detected. Water stress increased the Lesions caused by B. mediterranea and Phomopsis sp., but limited those of P. cinnamomi and the rest of the inoculated fungi. However, water stress did not significantly affect the damage caused by B. stevensii, which was the most virulent of the species tested. Leaf pathogens only showed their effects if the leaf cuticle was previously damaged. Lembosia quercina caused small dark lesions whereas D. myriadea and P. quercella produced large necrotic areas in well-watered plants. The lesions caused by the last two fungi were reduced by water stress.