Submitted to: Australian Grapegrower and Winemaker
Publication Type: Trade Journal
Publication Acceptance Date: 12/15/2002
Publication Date: 12/31/2002
Citation: LARDNER, R., MAHONEY, N.E., MOLYNEUX, R.J., SCOTT, E. EUTYPA DIEBACK:DEVELOPMENT OF EARLY DIAGNOSTIC TECHNIQUES. AUSTRALIAN GRAPEGROWER AND WINEMAKER. v. 461. p. 78-79. 2002. Interpretive Summary: "Dying-arm disease" or "dieback" is a disease of grapevines caused by the presence of a fungus in woody parts of the plant. The fungus causes withering of new shoots and leaves and reduced fruit yields. Ultimately the whole vine is killed. The presence of the fungus itself is difficult or impossible to detect. Progress in attempting to diagnose the disease by detecting the presence of specific toxic components produced by the fungus is outlined.
Technical Abstract: Eutypa dieback, caused by the fungus Eutypa lata, is a major threat to the sustainability and productivity of vineyards throughout the world. A primary need is to develop non-destructive techniques that will enable early detection of dieback before the pathogen has spread extensively through the grapevine. The production of secondary metabolites by 11 strains of E. lata, originating in Australia, America, New Zealand and Europe was analyzed using high performance liquid chromatography. A range of acetylenic phenol metabolites was detected and production was strongly influenced by both strain of fungus and type of media. The most abundant compound was eutypinol, structurally related to eutypine, the supposed phytotoxin, and was produced by 9 of the 11 strains examined, whereas eutypine was produced by only 4 strains. In order to determine the phytotoxicity of secondary metabolites produced by individual strains of the fungus, the purified culture filtrates containing all metabolites extracted from each strain were bioassayed on Cabernet Sauvignon leaf discs. Ten strains of E. lata produced culture filtrates that were toxic towards the leaf discs. The results indicate that phytotoxicity is the result of a suite of compounds, rather than the single compound, eutypine.