Infection of Grapevines by Some Fungi Associated with Esca. II. Interaction among «Phaeoacremonium chlamydosporum, P. aleophilum» and «Fomitiporia punctata»
Phaeoacremonium chlamydosporum (Pch), P. aleophilum (Pal) and Fomitiporia punctata (Fop) most commonly associated
with esca of grapevine. The experiments were carried out in southern Italy on grapevines cv. Italia and Matilde,
and the inoculations were performed in January 1999 by infecting trunks (cv. Italia) and branches (cv. Matilde)
through wounds. Fop, Pch and Pal were inoculated singly or in groups of two or three in all possible combinations.
Pch, Pal or both were inoculated above or below the inoculation site of Fop. From the results obtained in the first
eight months of experiments planned for three years, the following conclusions can be drawn. All fungi inoculated
singly spread along the woody tissue and caused brown streaking downward and upward along the trunk and branches
of inoculated vines. On the basis of internal symptoms, vines cv. Italia were more susceptible than those cv. Matilde;
in particular, the brown wood-streaking induced by P. aleophilum was much more severe on cv. Italia. Co-infection
with the two tracheiphilous species of Phaeoacremonium caused wood gummosis and discoloration, whereas the
lignicolous basidiomycete F. punctata alone caused wood deterioration and decay (white rot). Severity of internal
symptoms, assessed as extent and colour of the discoloured wood, varied with the growth and interaction of the
inoculated fungi. The wood discoloration caused by F. punctata was not hampered by P. chlamydosporum, but it was
always limited by P. aleophilum. A similar interaction was observed in vitro with cultures of the three fungi together,
which showed a marked antagonistic effect of P. aleophilum against F. punctata. Although not consistent, foliar
symptoms (interveinal and marginal chlorotic areas) developed within six months on ‘Matilde’ vines co-inoculated
with either species of Phaeoacremonium, or within three months after a syringe containing a liquid culture of P.
chlamydosporum was inserted into current-season ‘Italia’ shoots.
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