Phylloxera

The Victorian Department of Primary Industries has announced a second round of vineyard surveys in Victoria, covering Ballarat, Macedon Ranges, Sunbury, Broadford, Kilmore, greater Geelong, and a large northern area extending from Cobram to Horsham. The aim is to increase the number of regions within the Phylloxera Exclusion Zone (PEZ); if there is no evidence of phylloxera in the areas surveyed, it will enable growers and winemakers to move grape vine material and grapes into South Australia, New South Wales and those part of Victoria already designated as PEZs with a reduced regulatory burden.

New South Wales (except for a small and largely irrelevant area in the immediate west of Sydney) is phylloxera-free, as is the whole of South Australia (and Western Australia).

Phylloxera appeared in Geelong in 1887, and notwithstanding the enforced removal of all of the vines in that then very important region, phylloxera worked its way north, ultimately arriving in the Rutherglen region in the last few years of the 19th century, and into the early years of the 20th century.

Somehow or other, its northward march spared the Grampians and the Pyrenees. That is where things rested until in the last decade or so of the 20th century, phylloxera appeared in the King Valley, and thereafter the Strathbogie Ranges. Phylloxera cannot travel more than five kilometres without finding grape vines to feed on. Thus it is almost certain the King Valley and Strathbogie infections were carried by viticultural machinery that had been inadequately sterile-cleansed before moving from north-east Victoria to those two regions.

In 2006 it appeared in the Yarra Valley, which – against all the odds – was not attacked in the 19th century. Given that the Swiss were the most important vignerons in the Yarra Valley and Geelong alike, one might have expected there would have been exchange of grape vines or grapes between the regions, but chance intervened to protect the Yarra. Its luck has now run out, and phylloxera has arrived, almost certainly from the King Valley or Strathbogie.

Once introduced, phylloxera is like a cancer. It may move slowly, but it does so inexorably. Moreover, while agricultural equipment and grapes cannot be taken outside the Phylloxera Infected Zone (PIZ) in the Yarra, wine tourists have no such embargo. Four different vineyards are now impacted, and the number will increase in the future.

This, however, is not the cataclysm that headline writers delight in. Contingency plans should already be in place for vignerons, especially those with plantings in various parts of the Yarra Valley, who will have a program mapped out that will focus in the first instance on blocks that are underperforming and need either a replacement variety, a change in row orientation and/or in planting density, or will simply be taken back to pasture. The best blocks will be kept in production until it’s obvious that phylloxera is around the corner.

The cost of replanting the Napa Valley vineyards was estimated to be $1 billion, but the benefit of replanting didn’t take long for the investment to be repaid with higher quality grapes meeting the needs of the market.

In 1991/92 phylloxera began to destroy the vineyards of the Napa Valley; it had been an earlier visitor, but the Californians elected to use a rootstock with one of the parents vitis vinifera simply because it guaranteed high yields. The French warned that it would not be immune to phylloxera, and were proved right. When the damage began, various institutions ran for cover, asserting that the phylloxera that had now arrived was a different biotype.