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

Abstract

Summary 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 cf. 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.

Endemic and Emerging Pathogens Threatening Cork Oak Trees: Management Options for Conserving a Unique Forest Ecosystem

“…The fungus is fairly rare, but on the trees its infection may be severe. Pathogenicity tests on seedlings have confirmed the virulence of this pathogen (Luque et al 2000).…”

“…Two species in particular, Diplodia corticola and Biscogniauxia mediterranea, were found to be the most widely distributed pathogens in declining cork oak forests; the first has been considered the most virulent cork oak pathogen (Linaldeddu et al 2009b;Luque et al 2000). Attacks of D. corticola, originally misidentified as Diplodia mutila, were reported on cork oak trees in Italy, Morocco, Portugal, Spain, and Tunisia (Alves et al 2004).…”

“…In literature, more than 300 species of fungi and oomycota are reported on cork oak, of which at least 100 are pathogenic (Franceschini et al 1993;Luque et al 2000). Fortunately, very few are primary pathogens able to attack healthy tree tissues, the majority being opportunistic pathogens that colonize oak tissues when they have been previously weakened by abiotic or biotic factors (Luque et al 2000). Recently, some species of opportunistic fungi have received greater attention, because they can colonize oak tissues as endophytes without inducing disease symptoms for a long time (Gonthier et al 2006;Moricca et al 2012).…”

Interactive effects of drought and pathogens in forest trees

“…Negative effects of drought on the development of P. cinnamomi in soil or in bark have often been reported [32,116,125,195] whereas synergistic interactions between drought and infection have been demonstrated on tree physiology and the severity of disease symptoms [20,128,129].…”

Characterisation of synnematous bark beetle-associated fungi from China, including Graphium carbonarium sp. nov.

“…It appears to be a casual associate of many tree wound-inhabiting insects (Geldenhuis et al 2004;Kamgan Nkuekam et al 2008), and is primarily known as a sap-staining fungus associated with dead or stressed hardwood trees (Luque et al 2000;Harrington et al 2001). It has been suggested to exhibit some pathogenicity (Luque et al 2000;Geldenhuis et al 2004), and has for example been linked to Chinese fir wilt, associated with Crypturgus infestations in Taiwan (Lin et al 2003). Ophiostoma quercus has also been isolated from Betula and Quercus in Japan (De Beer et al 2003;Chung et al 2006) and logs of P. densiflora and P. koraiensis in Korea (Kim et al 2007).…”