Australia’s devastating 2019-2010 bushfire season has caused profound loss of ecosystems, property and life, including substantial damage to many grape growing regions including the Adelaide Hills, Tumbarumba and Kangaroo Island. One third of Adelaide Hills’ vineyards or approximately 1,100 hectares of vines were burnt, affecting 60 growers and winemakers. In southern NSW in the Tumbarumba region 19 vineyards were burnt and on Kangaroo Island eight vineyards and one winery have been lost.
Two leading institutions are working with grower groups to provide research and support to these growers and winemakers. The Australian Wine Research Institute (AWRI) have been working in this field for the past 17 years both locally and internationally, researching ways on how to decrease smoke impacts. Along with the National Wine and Grape Industry Centre (NWGIC) are providing their expertise and facilities to make wine from samples of smoke affected grapes, helping growers and producers to make decisions on their 2020 vintage.
Assessing Damage to Grapevine
According to the (AWIA), it is difficult to assess the damage to a fire-affected vineyard. In some cases it may take months as some vines appear alive and relatively, only to die a month or two later.
There are the obvious effects of burnt bark and leaves, but some effects that aren’t as visible, such as internal damage to vines.
The major cause of long-term decline or death after fire exposure is the effect of radiant heat. This heat causes internal damage to the Cambrian layer, a narrow layer of cells that houses the vascular system which moves water and nutrients through the vine. Damage to the Cambrian layer is permanent and greatly reduces the life of the vine.
Some vines may be burnt on one side and survive but this renders the vine susceptible to termites and disease and reduces the long-term viability of the vine.
To promote recovery of vines, vines are assessed for damage. Highly damaged vines will not produce viable crops again and will be pulled; however, moderately damaged vines will have remaining bunches of grapes, leaves and shoots removed and irrigation systems are repaired or installed as necessary.
Assessing Damage from Smoke Taint
The cost of the physical damage can generally be immediately assessed. However, the cost of smoke taint not only on surviving vines immediately affected by flames, but also in wine regions that are indirectly affected may take time to assess.
Along with the Adelaide Hills, Tumbarumba and Kangaroo Island, regions that have had persisting smoke include the Hunter Valley, Canberra, the Alpine Valley, Gippsland, Mudgee, the Southern Highlands and Gundagai (see map).
What is Smoke Taint?
When vineyards and grapes are exposed to smoke, the wine can taste “smoky, burnt, ashy or medicinal”, according to The Australian Wine Research Institute (AWRI). Within a region smoke taint will not be universal so each vineyard will be affected differently.
Smoke related particles from burning wood, called volatile phenols, enter into the grape directly via the waxy cuticle and bond quickly with grape sugars. The phenols can also enter through the leaves, but uptake is much slower.
The AWRI fact sheet on smoke taint says there are several factors that influence uptake:
- Grape vine growth and development.
The closer the harvest, the higher risk of smoke taint. From the onset of ripening (veraison) the risk is medium and at pre-harvest is high.
- Grape variety
Grapevines differ in sensitivity; this is an area requiring more research.
- Smoke composition
The chemical composition of smoke changes in the atmosphere and over time concentration of volatile phenols lessens. Smoke from recently burnt wood will be higher in volatile phenols, therefore having greater potential to taint grapes.
- Smoke exposure
More research needs to be conducted to understand what level of smoke exposure will cause smoke taint. Low levels (visibility greater than 10-15kms) is generally thought not to result in a perceptible effect.
Counting the Cost
Executive Officer of the NSW Wine Industry Association Angus Barnes said that the impact of the fires comes on top of the drought, which had already reduced grape yields significantly. Mr Barnes says, “We are looking at losses of $100 million or more, especially when you take into consideration the disastrous impact on wine tourism the fires have had.”
Harvest in the Hunter Valley is already underway and with lingering smoke covering the region since October, many vineyards are being left unpicked. Most notably premium producer Tyrrell’s made the call to forgo 80% of their 2020 vintage, a decision to protect their brand. Sample testing on their grapes was conducted by the Australian Wine Research Institute and Dr Ian Porter from Victoria’s La Trobe University, as well as on their own micro-fermentations.
In Victoria, Chair of Wine Victoria, Angie Bradbury, says “The scale of the impact will vary greatly depending how close to the fire front the vineyards were, and what stage of ripening the grapes were at when the smoke was at its worst. The effects will be potentially quite isolated. And many of Victoria’s wine regions have not been affected at all. We need to be careful about doomsday language.”
Brian Smedley, CEO of the South Australian Wine Industry Association, was also cautious about overstating the state-wide impact of the fires. “Many regions are a long way from harvest and it’s too early to tell what, if any impact there will be from smoke,” he said. “Our main concern now is to support those regions directly affected by the fires by sending out the message that, in the Adelaide Hills for example, it’s business as usual and people should come and visit the cellar doors.”
South Australia Wine Recovery package
The Wine Industry Development Scheme has released a $330,000 recovery package which includes subsidised smoke taint laboratory tests ($300 per test) to growers in Adelaide Hills and Kangaroo Island.
The recovery package also includes $100,000 for an AWRI-led study in the Adelaide Hills into early identification of smoke taint damage on wine grapes. This is great news for the industry and research from which all producers will benefit.
AWRI General Manager Business Development Mark Krstic said “the current best practice for smoke taint testing in wine grapes could only be conducted two to three weeks before harvest, with no reliable testing methods available for the earlier stages of the growing season. If the results can lead to a reliable early testing process, it will transform the way industry bodies, grape growers and government respond to fire and smoke damage into the future.”
The State Government has also launched a #BookThemOut campaign to encourage tourists to return to Kangaroo Island and the Adelaide Hills.
How We Can Continue to Help
Whilst bushfire has directly impacted regions, the industry as a whole has been affected by a downturn in tourism, and the season still has a long way to go. The best way to help is to keep enjoying wine, buying local and visiting wine regions to support local tourism.
Kangaroo Island business, Springs Road Wines, was still unclear if their 10ha Cygnet River vineyard planted with Shiraz, Cabernet and Chardonnay, would be affected by smoke taint from the early January fires that passed within a few kilometres. They are waiting on their results from smoke taint testing. Owners, Joch Bosworth and Louise Hemsley-Smith, who also own McLaren Vale winery Battle of Bosworth, say that “At this stage we’re open and we’re just keeping on and waiting to see what’s going to happen, but the damage so far has been from a falling off of visitor numbers.”