Phylloxera strikes the Yarra Valley

This article first appeared in Spectator, 2009
Tyson Stelzer

A new Phylloxera outbreak in Victoria’s prestigious Yarra Valley has sparked concern over the extent of the spread of the aphid across the wine region.

Phylloxera attacks non-resistant vine rootstock, ultimately destroying the vine. Because the symptoms are delayed, detection typically occurs some years after the initial infestation.

The find came exactly two years after the first discovery of Phylloxera in the Foster’s owned Beavis vineyard in the Coldstream area in the centre of the Valley in December 2006.

At the time, a “Phylloxera Infestation Zone” (PIZ) was declared and strict quarantine restrictions were placed on all vineyards within a three mile radius of the affected site. When further outbreaks were discovered in nearby vineyards in early 2008, Fosters immediately commenced destruction of all of the vines in the 32 hectare vineyard.

The new outbreak occurred in Foster’s Racecourse vineyard, some two-and-a-half miles from the Beavis site, and close to the edge of the original PIZ. It is believed that Phylloxera was transferred by tractor movements between the two vineyards prior to the 2006 discovery and subsequent establishment of quarantines.

An extension to the zone was announced last week following meetings between the Department of Primary Industries and the Yarra Valley Wine Growers Association.

At a public meeting, Dr Tony Jordan, President of the Yarra Valley Wine Growers Association announced that “given the experience of other areas where Phylloxera has been found, on the balance of probability, there will be further outbreaks and ultimately the whole Yarra Valley will have to be declared a Phylloxera zone.”

The extension of the zone comes at an awkward time as the Valley prepares for the commencement of vintage. The quarantines place strict control on the movement of equipment and grapes into and out of the zone, creating nightmares for wineries sourcing fruit from both inside and outside of the area. As an interim measure this vintage, permits will be issued to allow grapes to be transported out of the newly declared zone under stringent regulations.

“At this time of developing weakness in the Australian wine and grape industry… and at a time of world economic recession, the increased uncertainty because of possible (and likely) continuing changes to the declared Phylloxera zone(s) means some Yarra Valley wine or grape businesses will find it too hard to operate in the Valley,” said Dr Jordan.

While some seventy to eighty percent of the Yarra Valley’s vineyards remain on non-resistant rootstock, Jordan was quick to downplay alarmist suggestions that Phylloxera could wipe out the region.

“The Phylloxera detected in the Yarra Valley is a very slow-moving ‘Type B biotype’ which only spreads by human or machine contact, so no one is expecting it to move like wildfire as it did in New Zealand or California,” he explained. “Rutherglen has lived with the same Phylloxera for more than a century and by enforcing strict quarantines, it has vineyards that remain Phylloxera-free. We are confident that we will be able to control its spread.”

The discovery has sparked concern in Phylloxera-free South Australia, where the largest collection of old commercial vines in production in the world is planted on non-resistant rootstock. The Phylloxera Board of South Australia last week issued a warning to growers of the risk of the aphid being brought into vineyards by interstate tourists during the Tour Down Under cycle race.

McLaren Vale Grape, Wine and Tourism Association chair Dudley Brown suggested that the recent Phylloxera spread in the Yarra Valley increased the likelihood of it reaching South Australia, although the statistical risk of the aphid being transferred by tourists was low.