Australia is at the forefront of research into the practical management of grapevine trunk diseases, leading the international effort in preventative wound protection, remedial control strategies and spore surveillance.
But eutypa dieback (ED), botryosphaeria dieback (BD), esca disease complex and young vine decline continue to have serious global economic impact, and the wine sector has much to learn.
Dr Mark Sosnowski from the South Australian Research and Development Institute (SARDI) recently returned from the 11th International Workshop on Grapevine Trunk Diseases in Canada, where he was keynote speaker on the control of grapevine trunk diseases in mature vineyards.
Mark shares a few highlights from the conference that the Australian wine sector can learn from.
Eutypa dieback, botryosphaeria dieback, esca disease complex and young vine decline continue to have serious global economic impact.
New detection methods
Dr Sosnowski says the development of rapid and inexpensive detection methods for trunk diseases using techniques such as loop mediated isothermal amplification (LAMP) and fatty acid methyl ester (FAME) analyses will not only improve research tools for developing management strategies, but also provide the Australian wine sector with improved diagnostic capability.
‘This is an exciting area and LAMP technology is already being developed for ED and BD as part of current Wine Australia research’, he said.
Inoculum dispersal surveillance is informing the sector about the prevalence of trunk disease pathogen spores throughout the year, and under different climates.
‘International research in this space is confirming observations from Australia and highlights the importance of protecting winter pruning wounds, and the need to consider susceptibility of summer pruning practices in future research.’
– Dr Mark Sosnowski
Outcomes from assumption-based economic analysis in California – which has since been confirmed in an independent analysis of survey data in New Zealand vineyards – impresses the importance of early adoption of preventative and curative trunk disease management strategies.
‘Vineyard profitability and longevity can be maximised using relatively inexpensive practices undertaken from planting, and consistently each winter following pruning’, he said.
The conference heard that a Greek vineyard trial found that application of the fungicide Tessior® (boscalid and pyraclostrobin) resulted in significant reduction of esca disease incidence and severity when applied either on the day of pruning or six days after. Pyraclostrobin has been reported to be effective in control of ED and BD in Australia. The long-term trial in Greece will continue to monitor disease incidence with regular winter post-pruning applications of Tessior.
Eutypa grows slowly, causing stunted shoots and progressively killing spurs, cordons and trunks and eventually the entire affected vine.
Cross-sections of cordons with stunted shoots reveal characteristic dark brown, wedge-shaped zones of dead wood. These zones can be traced back to cankers.
Co-infection of grapevine with multiple pathogen combinations may affect disease severity.
The findings of one study suggest that an infection by a grapevine trunk disease pathogen may induce systemic changes in host physiology that could alter progress of an independent infection elsewhere in the vine.
Dr Sosnowski said there was immense international interest in the pro-active nature of the Australian wine sector towards grapevine trunk disease.
‘Australian grapegrowers have a great advantage with access to a range of options for wound protection that many countries do not, thanks to local research that is leading the world in developing practical management strategies for trunk disease’, he said.
Dr Sosnowski said it was important to continue the search for alternative natural compounds or biocontrols for wound protection; and to evaluate rootstock and scion material in the search for greater tolerance to trunk disease.
‘We also need to work towards a better understanding of the risk of wound infection at all times of the year – and the complex relationships between spore dispersal and climate variables.’
The report from Dr Sosnowski’s travel can be found here. Dr Sosnowski was a recipient of a Wine Australia Travel Bursary. Applications for the next round of Travel Bursaries will open the first Friday in April 2020.