Developments in Grapevine Trunk Diseases Research in Australia

Abstract

In Australia, trunk diseases of grapevines are becoming increasingly important. Phaeoacremonium chlamydosporum causes black goo decline and is very common in newly planted vineyards in which establishment is slow and uneven. It is apparently introduced to these vineyards as infections of the propagating material. We have isolated the fungus many times from rootstock mother vines and speculate that it spreads from the trunk of the mother vine to the canes which are later harvested as cuttings. Histological studies of inoculated vine shoots in tissue culture, show that the fungus infects the xylem parenchyma cells as intracellular hyphae, and these cells produce tyloses in the adjacent xylem vessels. The hyphae also penetrate the vessels, often by way of the tyloses. Brown deposits (black goo) are seen in vessels and cells, often some distance from active hyphae. Phaeoacremonium chlamydosporum has also been found to produce pycnidia on the surfaces of infected wood when moist incubated. The same pycnidia were also found on the surfaces of inoculated tissue culture vines, proving that they are pycnidia of P. chlamydosporum. The spores produced by the pycnidia appear to be conidial rather than spermatial as they germinate readily on agar and develop normal colonies. Esca was formally diagnosed for the first time in Australia in 1999, although it is believed to have been present for many years. In addition to Phellinus (Fomitiporia) punctatus, we have also found a second species of Phellinus associated with similar symptoms. This species differs from P. punctatus in the production of setae on host tissue and in culture. Like P. punctatus it has a close association with Phaeoacremonium chlamydosporum. Eutypa dieback appears to be increasing in severity in Australian vineyards and may be a major limiting factor in the sustainability of Australian wine production. A national trunk disease project has commenced to develop management strategies for black goo decline, esca, Eutypa dieback and other trunk diseases.