NOTAS FITOPATOLÓGICAS / PHYTOPATHOLOGICAL NOTES

Inonotus splitbergeri A STEM PATHOGEN OF Eucalyptus globulus IN URUGUAY

Universidad de la República, Laboratorio de Micología, Facultad de Ingeniería, Montevideo, Uruguay

(Accepted for publication on 17/12/2001)

Corresponding author: Sebastián Martínez

Inonotus splitbergeri é relatado pela primeira vez o Uruguay causando podridáo-do-lenho de Eucalyptus globulus. Durante as tempestades ocorre o tombamento de árvores, mesmo daquelas totalmente enfolhadas.

During recent years lesions of variable length and width on the trunk of standing trees from butt to 2 m height were observed in plantations of Eucalyptus globulus Labill. Primarily located in the south-east of Uruguay where their incidence ranged from 8 to15%. The disease also occurs in the western region but with lower frequency (ca 5 %). The typical symptoms were a flattening deformation of the trunk corresponding to a lesion resulting from axially cracked bark, exposed xylem and, sometimes, margins with the protruding lips of callus. In a few trees bark growth covered the lesion so that the surface was complete but underneath a hollow cavity existed. When sectioned, axial white rot and discoloration in the xylem extended proximally and distally from lesions to near the top of rotted stems. Many trees, even those in full leaf, are unstable, as in a sudden storm. Inonotus splitbergeri (Mont.) Ryv was the fungus associated with lesions, individually or in groups, attached to bark or damaged xylem. This species has not previously been reported in Uruguay, but was only found from Brazil to Mexico on Moraceae, among other hosts (Ryvarden, personal communication). Fruit bodies were also presente on fallen stems and stumps resting on the ground. Infected stumps sometimes sprouted but, in general, the sprouts died afterwards. Typically, as for other Inonotus species, the flesh of fruit showed a positive reaction to KOH solution, becoming distinctly red. Each fruit produces a high number of spores, which represents a potential risk of contamination for plantations. Several species of Inonotus were found to be associated with heartwood rot in the butt, major roots and in the upper trunk and major branches of Eucalyptus spp. in Australia and Brazil (Keane et al. 2000, Diseases and Pathogens of Eucalyptus, CSIRO) and also to a large number of broad–leaf trees in the northern hemisphere (Schawrze et al., 2000, Fungal strategies of wood decay in trees, Springer).