The Australian wine industry is better prepared for an incursion of angular leaf scorch (ALS), a significant fungal disease of grapevines, thanks to the work of scientists at the South Australian Research and Development Institute (SARDI).

With funding from Wine Australia, scientists from SARDI undertook a collaborative project with Cornell University in the US to develop contingency plans for ALS at the New York State Agricultural Experiment Station.

Angular leaf scorch is an economically significant disease of grapevines which occurs in north-eastern North America but has not been reported in Australia, where it is listed in the Viticulture Industry Biosecurity Plan as a high priority exotic plant pest threat.

“The disease, caused by the fungus Pseudopezicula tetraspora, results in scorching and defoliation of leaves and berry stalk infection which could cause significant yield loss in Australian vineyards (of up to 90%) if it becomes established and would incur significant costs to manage,” said Dr Mark Sosnowski, who led the research team.

“Therefore, it is vital to ensure that we prepare for a rapid and effective eradication response in the event of an incursion.”

As a result of the project, a diagnostic protocol for ALS has been developed and the threat to the Australian wine industry has been established, based on the susceptibility of our grape varieties. Riesling was found to be extremely susceptible, Sauvignon Blanc, Cabernet Sauvignon and Pinot Noir, moderately susceptible, and Chardonnay, Shiraz and Merlot, slightly susceptible.

To manage an incursion, three fungicides (trifloxystrobin (Flint), pyraclostrobin (Cabrio) and tebuconazole (Folicur)) belonging to distinctive chemical groups representing two different modes of action, and already used in Australia on grapevines, were shown to be effective in controlling ALS.

“And if an incursion of ALS occurred in Australia, a drastic pruning protocol based on cutting trunks and removing all upper parts of the vine, previously validated for eradication of black rot disease, has the potential to save the wine industry many millions of dollars in lost production and vineyard re-establishment costs,” Dr Sosnowski said.

“This information will be valuable in the containment or eradication of ALS in Australian vineyards, should an incursion occur.”

Learnings from this project will inform new information to be presented about ALS in the revised Viticulture Industry Biosecurity Plan.

To read the full ALS project report, click here. 

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