Investigation into the Presence of Fungi Associated with Esca of Young Vines

Abstract

Thirty one 5 to 6-year-old grapevines with esca foliar symptoms, aspecific foliar symptoms, apoplexy and no symptoms at all were uprooted and examined in the laboratory for type of wood deterioration and presence of fungi. Various types of deterioration were recorded in the wood, three of which were found in all vines: necrosis originating in the cane stumps, sparse blackish streaks or blackish halos around the rootstock pith. Spongy decay was observed on six of the eight grapevines with the foliar symptoms of esca. Blackening of some roots was found on apoplectic vines. Among the fungi involved in esca, Phaeoacremonium chlamydosporum was isolated especially from the blackish halos around the rootstock pith, while Eutypa lata only from cane stump necrosis; but both were present on grapevines with and without foliar symptoms. Fomitiporia sp. was present only in spongy decay on vines with foliar esca symptoms. This fungus seems able to produce spongy decay only in necrotic tissues, but the necrosis itself could also be caused by non-parasitic factors. It was difficult to relate foliar symptoms to pathogen presence; it is necessary to examine a far larger number of samples to gather more accurate information.