The jury is still out on whether a viral infection of the Gingin Chardonnay clone is the ‘secret ingredient’ behind the sought-after unique nature of some West Australian Chardonnays.
Researchers in the Department of Primary Industries and Regional Development in Western Australia have been investigating whether grapevine leaf roll virus (GLRaV) can act favourably on vine phenotype, performance and wine quality in Chardonnay.
In an Incubator Initiative project supported by Wine Australia, researchers aimed to show a detectable difference between small batch wines made from grapevines with and without virus when assessed by a panel of experts.
The Gingin clone is known to have a high level of GLRaV1 infection and the survey conducted in this project supported that.
Lead researcher Dr Monica Kehoe, a Molecular Plant Pathologist with the Department of Primary Industries and Regional Development in Western Australia, said while the survey was limited, ‘everything we sampled from Gingin clones had GLRaV1.’
‘The only other virus we tested these same samples for was GLRaV3, and it was not as prevalent as GLRaV1, but was detected in a small number of samples’ (i.e. dual infection with GLRaV1 and GLRaV3).
It is thought that infection with one or both of these two viruses can cause a decrease in overall vine health and reduced fruit quality and yield. However, there have only been a few studies that have investigated the impact of these effects on the resulting wine quality, and they have primarily focused on red varieties.
But what about the difference between the small batch wines made from fruit with or without virus?
‘The main question we asked experts on the sensory evaluation panel was whether there was a difference in the wines, not whether it was a “good” or “bad” difference’, Dr Kehoe explained.
Overall, the small group of experts used in this study weren’t able to reliably pick the difference between a wine made with or without virus, although one particular expert was able to consistently pick the difference.
‘This one individual result shows that the difference may in fact be noticeable to an expert and that further research is likely worthwhile’, Dr Kehoe said.
‘It would be great to be able to perform some replicates of the experiment with the Chardonnay, and also to extend the experiment to other varieties, including some reds. In speaking with growers throughout the course of this small study one of the most common questions I was asked was whether or not we were going to do other varieties?’
‘It’s important to understand whether or not the Gingin virus-infected fruit has an effect on the wine quality and taste. Generally, virus infection is considered to not be a good thing, and current best management practices in the vineyard are built on this foundation.
‘If it is found that it might be a beneficial quality, we will need to understand if that is consistent for all varieties, or just some, and under what conditions we see the effect’.
The project's Final Report is available here.
