Pathogenicity evaluation of Cytospora eucalypticola isolated from Eucalyptus spp: cankers in Uruguay

Abstract

Cytospora eucalypticola has been frequently associated with twig and stem cankers and as endophyte of Eucalyptus globulus and E. grandis in Uruguay. Mycelium discs of two C. eucalypticola isolates obtained from actively growing colonies were inoculated, both superficially and on experimentally wounded stems of E. globulus and E. grandis. No inoculated and control plants have shown any discoloration, gumosis or necrosis nor did they display lesions ten months after inoculation. Callus tissue was formed, partially or wholly occluding the wounds. The ability to penetrate healthy tissues and the inability to produce lesions evidenced that the presence of C. eucalypticola in twig and stem cankers could result from saprotrophic expansion of the endophytic mycelium in dying tissues, cankers probably being produced by different environmental stress conditions.

Fungi associated to bark lesions of Eucalyptus globulus stems in plantations from Uruguay

“…C. eucalypticola was nearly absent from the lesions of the youngest plants (purple cracked bark with exposed xylem) in site 3, but they were very frequently isolated from bark cracked with xylem unexposed (symptom I, of site 2) and with xylem exposed (48 %) (symptom II, site 1). The potential pathogenicity of Cytospora eucalypticola isolates was evaluated by experimental inoculation on E. globulus and E. grandis stem and did not evidence the ability to incite symptoms, although they were recovered from tissues at the inoculation court (ALONSO et al 2005 One group of isolates of Botryosphaeria identified by means of molecular methods showed a high homology with B. ribis (98%) and the other group, with B. eucalyptorum (100%) (SMITH et al, 2001). These species were indistinctly obtained from all bark lesions and healthy tissues.…”