Breaking News: Phylloxera found in the Yarra Valley

Against all the odds, the Yarra Valley escaped phylloxera in the mid 1870s when it appeared at Fyansford near Geelong, in Victoria. Today, however, its luck has run out, for the world’s most feared viticultural disease has now arrived, right in the heart of the region. It has been detected in a small section of eight year-old merlot vines in the Fosters-owned 32 ha Beavis vineyard, sending shivers up and down the region. At the time of writing, the region is being inspected with the viticultural equivalent of a fine-toothed comb to determine just how far the infection has spread.

This infamous root-eating aphid-like insect or louse attacks the roots of grapevines, ultimately causing their death through secondary infections and by cutting off their flow of nutrients and water. While the disease has long been a part of the viticultural scene of regions like the Nagambie Lake and northeast Victoria, only around 25 of the Yarra Valley’s plantings are on resistant rootstocks. Most of its vineyards are therefore totally vulnerable.

The affected site was quickly quarantined by the Victorian Department of Primary Industry. Set apart from the main St Huberts facility off the Maroondah Highway, it borders the Punt Road vineyard. The vineyard managers noticed that certain vines did not respond with typical regrowth after the last serious frost episode in the Yarra, which prompted the testing that revealed phylloxera’s presence.

The initial 5km exclusion zone around the affected vineyard includes properties such as Mount Mary, Yeringberg, Domaine Chandon, Punt Road, Yering Station, Yering Farm, Coombe Farm, Oakridge, YarraHill and St Huberts.

The immediate implications for these vineyards are extreme. Material and equipment may enter the zone from non-phylloxera declared regions, but are not able to return outside the zone without an exhaustive series of permits, procedures and conditions including the steam cleaning of equipment, the complete removal of soil and even heat treatment. A strict protocol will need to be observed by all contractors, pickers and those who use machinery such as harvesters and grape bins within the zone to ensure there is no possibility of the infection spreading outside.

Vineyards which in the past have sold grapes for processing by companies outside the zone will no longer be able to do so. Instead, all the grapes will need to be processed as juice within the zone prior to being able to leave. This might have very strong commercial implications for companies whose buyers are not prepared to accept this additional process and complication. Clearly, since they are more likely to be bringing fruit into the zone for processing rather than taking fruit from the zone, producers such as Domaine Chandon, Mount Mary, Yering Station, Punt Road and Yeringberg will be less affected than others such as Coombe Farm, which depends to a significant degree on its ability to sell fruit elsewhere.

Once the initial extent of the impact is determined, the DPI will initiate a long and exhaustive process to attempt to determine how the infestation occurred. Firstly, an exhaustive series of trace-back interviews will attempt to isolate incidences in which machinery or grape bins might have brought the disease from a known phylloxera region to the vineyard in question. It is entirely possible that this transfer – if indeed it happened this way – might have occurred before the phylloxera region was actually identified as such. It’s likely to take years for this means of investigation to produce anything concrete.

The second means of investigation is via DNA analysis, to attempt to match the strain of phylloxera found in the Yarra with an identified strain in a known phylloxera region. This is also highly unlikely to produce a result that matches the incidence with a known action or movement of machinery and it is also highly unlikely that enough evidence could ever be mounted to support a successful prosecution.

While it was really only a matter of time before phylloxera established itself in the Yarra, it could take years for the implications of its arrival to unravel. One hopes it will not appear in other vineyards, but the possibility certainly exists. We will have to wait and see. Since phylloxera can live for eight days on its own, it can be assumed not to be alive from nine days after the death of the very last vine root in an affected vineyard. However, vine roots can live for many, many years, especially in favourable climates such as that of the Yarra Valley. It took sixty years before vineyards were successfully re-introduced into Geelong. Please login to post comment