Take action to reduce phylloxera risk

Phylloxera is one of the most serious biosecurity risks for the Australian grape and wine community, with the potential to devastate vineyards and wreak economic devastation on rural communities.

Wine Australia and Vinehealth Australia are encouraging grapegrowers who are considering planting or replanting grapevines to use phylloxera-resistant rootstocks for at least a portion of their vineyard to future-proof their business against phylloxera.

Grape phylloxera (Daktulsphaira vitifoliae) is a tiny insect pest that destroys grapevines by feeding on their roots. Currently there are 83 genetic strains of phylloxera in Australia and, while impacts are dependent on the strain, generally once vines are infested, they die within six years – but the effects on yields are felt much sooner. There is no cure. Once infested, the only solution is to replant on resistant rootstock, selected based on site conditions and phylloxera strain.

Phylloxera’s arrival in Europe in the 1850s wiped out millions of hectares of vineyards within years. The pest is present in eight quarantine zones in Australia but good fortune and strict quarantine regulations have limited further spread.

However, Australia’s wine sector remains incredibly exposed to phylloxera. Susceptible, own-rooted vines make up the majority of the nation’s vineyards. Vinehealth Australia data shows that in South Australia alone, 74 per cent of vineyard hectares are planted to own-rooted vines – including some of the oldest vines in the world, which means that the stakes are extreme should phylloxera spread outside the current phylloxera-infested zones.

Wine Australia General Manager of Research, Development and Extension Dr Liz Waters said applying best practice farmgate hygiene and investing in resistant rootstocks should be considered as an insurance policy for grapegrowers across Australia.

‘Through our isolation as a nation and strict biosecurity practices, we have avoided much of the devastation that phylloxera has caused in other wine growing regions around the world. However, we can’t ignore the massive risk we face’, Dr Waters said.

‘While alone it cannot stop the spread of phylloxera, one of the most effective long-term practices is planting vines grafted on phylloxera-resistant rootstocks so that, if there is an outbreak, the immediate economic impact is reduced.’

Dr Waters acknowledged that planting vines on rootstocks is more expensive than own-rooted material but she urged wine businesses to think of the expense as an insurance policy.

‘If there is a phylloxera outbreak, vines on resistant rootstocks will not be affected, reducing the economic impact on the growers and the wider rural community. Even a portion of a property with vines on resistant rootstock offers a buffer against economic devastation. Rootstocks can also provide more immediate benefits by providing resistance to vigour-sapping nematodes and delivering better performance in drought and saline soils.’

While there remains a lot to learn about rootstocks and phylloxera resistance, Dr Waters urged grapegrowers to use Wine Australia’s free online Grapevine Rootstock Selector (www.grapevinerootstock.com) to pick the best rootstocks for their vineyard and seek expert assistance from their local nursery.

‘Choosing the right rootstock can eliminate many long-held concerns about quality. The Grapevine Rootstock Selector tool has extensive information on rootstock and scion compatibility and soil suitability, so that grapegrowers can take advantage of decades of research’, Dr Waters said.

Vinehealth Australia Chief Executive Officer Inca Pearce said every available tool was needed to prevent the spread and impact of phylloxera in Australia.

‘It’s critical that the grape and wine community works together to stop the spread of phylloxera’, Inca said.

‘Planting on phylloxera-resistant rootstocks is an important protective measure for long-term sustainability. However, rigorous farmgate hygiene practices and compliance with state quarantine regulations are vital in preventing the further spread of phylloxera.

‘We must work together to ensure that the own-rooted vines planted a decade, generation or century ago can continue to produce grapes for Australian wines that consumers around the world enjoy.’

Vinehealth Australia provides a range of resources on farmgate hygiene and specific rootstocks with varying resistance to key phylloxera strains at vinehealth.com.au/pests-and-diseases/phylloxera/phylloxera-strains/.