When we caught up with virus expert Dr Fiona Constable for a chat about her work in February, she also shared her views on how we can improve grapevine virus management.
Fiona, the Research Leader for Microbiology, in the Microbial Sciences, Pests and Diseases group at Agriculture Victoria, says five things are critical: understanding vectors, using high health planting material, improving surveillance, improving diagnostics and getting better at farm-gate hygiene.
“We desperately need to get a better handle on the transmission aspects of grapevine viruses in Australia,” Fiona said. “Many viruses, including grapevine virus A (GVA) and some leafroll viruses, are transmitted by mealybug and scale. And anecdotally, we’re seeing a lot more scale in vineyards.
“But we’ve never done a lot of work on what the vectors are in Australia, particularly for leafroll viruses and GVA. We don’t understand the transmission rates. And I think we need to better understand the biology of the insects in our vineyards.”
Fiona said that to better manage grapevine viruses, we need to start with high quality planting material, that has been pathogen tested.
“The grapevine is your primary investment, so buying healthy, disease-free vines is your starting point,” she said.
“Then, if you’ve got a virus, you need to know how to manage it to minimise its impact. And critical to that is vector control.”
One of the projects within Fiona’s Microbiology team is focused on gaining an understanding of the potential vectors for Xylella in Australia.
“The team is also looking at diagnostics for Xylella, using the new high throughput sequencing technologies, which is very exciting. The future will include the development of an infield diagnostic tool for viruses in grapevines,” Fiona said.
“Surveillance is also key in virus management. The sooner you can determine the extent of an infection, the more possible eradication is.
“And to prevent the spread of viruses – and most pests and diseases – vineyard hygiene is critical.
“If a grower knows they have a virus that’s vector-borne, they should start work in the cleanest part of the vineyard and then move to the areas where they’ve got disease. Start with clean and move to dirty.”
Fiona said growers should also clean machinery and equipment thoroughly to remove vectors after they’ve been into a known or suspected virus area, to prevent the spread of the virus into other parts of the property, or onto other properties that don’t have a problem.
“And changing their clothes after they’ve been into a part of the vineyard with a known virus issue is also a very good idea,” Fiona said.
“It’s a similar approach to phylloxera control. It’s hard, but it’s important if we want healthy vineyards.”
Fiona also encourages growers to get vines tested when they see anything unusual. “Don’t rely on symptoms – virus symptoms can easily be confused with other things. If you think you may have a virus problem, get it tested and confirmed,” she said.
“The sooner you know what it is, the easier it is to manage, and the better it is for our industry as a whole.”