Wine Industry Newsletter

Downy mildew study heads to USA

WA was one of the few remaining grape growing areas of the world to not have grape downy mildew until the 1998/99 season. Since its arrival it has now spread to all regions within the state and sporadically causes issues when weather conditions are right for it to rapidly multiply. Questions have long been raised as to where the disease came from and how it survives with WA’s hot summer periods and relatively dry grape growing environments.

Over the last two seasons DAFWA plant pathologist and PhD candidate Andrew Taylor has been collecting samples of grape downy mildew from across the state and Australia as part of his studies to try and answer some of these questions. Andrew is using molecular tools to take the DNA of the disease and compare it with populations found elsewhere. This will enable a direct comparison of populations found within a vineyard, between regions and even between countries.

Downy mildew infected grape bunch.
Downy mildew originates from north eastern America and has successfully spread around the world with the movement of grape material.

Andrew is undertaking an expedition to America to collect DNA samples of the disease from its place of origin to determine how much alike or different they are to WA and Australian isolates.

Other work within his PhD study is to determine how the disease survives WA winters. Trials have been investigating whether the disease can remain viable over winter in canes, buds and leaves. This could impact early season management of the disease in WA. No definitive results of this work are available at this time.

Despite having a number of samples from the Swan Valley and Margaret River; if you are a grape grower in the Pemberton, Manjimup, Frankland and Great Southern regions and have an issue with downy mildew in the coming season please contact Andrew Taylor on +61 (0)8 9780 6241.

The more samples from these regions that are collected, the more robust the population analysis will be.