Following a recent comprehensive review of Grapevine Pinot Gris Virus (GPGV) in Australia, grapegrowers have been urged to take precautions to limit the spread of the virus.
Vinehealth Australia technical manager Ms Suzanne McLoughlin led the study, which aimed to improve understanding of the virus, its epidemiology and its distribution and potential in the Australian context.
‘Until we fully understand the impact of GPGV on different grape varieties in Australia it’s important to curb its spread via infected propagation material.’
GPGV was first identified in Italy in 2012, when it was found to be associated with symptoms of grapevine leaf mottling and deformation – known as GLMD – in the variety Pinot Gris. Since then, the virus has been found in other wine, table and rootstock varieties across the globe, although many of them do not exhibit GLMD symptoms.
Suzanne McLoughlin recommends growers ensure that in planting or grafting situations, GPGV is included as part of a full virus screen of the propagation materials.
GPGV was first detected in Australia in 2016 and is currently classified as established and present in New South Wales, South Australia and Victoria.
‘Finding a new virus means the inevitable question – is it a virus we should be worried about? Will it impact yield and vine growth? Or is it just like Rupestris Stem Pitting associated virus which is one of the most prevalent grapevine viruses worldwide and has not been found to be detrimental to vine health?’
Ms McLoughlin said the review was an important stepping stone to answering some of those questions – ‘because at the moment, there are clear gaps in our knowledge of the virus – and therefore its potential risk to Australian viticulture.’
In the face of limited knowledge, the review called for a survey of vineyards and the re-introduction of border testing for GPGV at post-entry quarantine (PEQ) facilities.
‘GPGV is already in Australia, so we need to quantify current levels of infection in Australia – and therefore the potential issue posed and its impact on production or vineyard sustainability.
‘Until we fully understand the impact of GPGV on different grape varieties in Australia it’s important to manage its potential spread via infected propagation material’, said Ms McLoughlin.
A preliminary sampling project associated with the review identified a number of sampling strategies to assist the vine improvement and nursery sector in reducing the risk of spread via propagation material.
Management recommendations to growers include control of possible vectors – grapevine bud or blister mite – demonstrated overseas to transmit GPGV between grapevines.
‘Minimising spread of GPGV within a vineyard block and between blocks is therefore likely to be moderated through active mite control in commercial vineyards,’ Ms McLoughlin said.
However, more information on potential vectors, virus variants and possible host plants in Australia is needed to better articulate management strategies for Australia.
She recommended growers ensure that in planting or grafting situations, GPGV was included as part of a full virus screen of the propagation material. General monitoring for symptoms of delayed budburst, stunted shoots, yellowed mosaic, mottled or distorted leaves – all most apparent early in the growing season – would also help in identification.
‘With limited knowledge of GPGV to date, but with reports of negative impacts to vine growth and yield in some varieties overseas which we also have in Australia, as a community it’s best to take a cautious approach to investigating the relevance of the virus to the Australian situation.’
A factsheet based in the findings of the review is now available here and further GPGV resources are available here.