Battling smoke taint in the vineyard
Recent fires in Australian grapegrowing regions, including in Tasmania and North East and Eastern Victoria, have again raised concerns about the possibility of smoke taint in finished wines. AWRI Victorian Node Manager Mark Krstic said that the best way for growers to manage smoke taint before it reaches the winery is to avoid smoke being around the vineyard in the first place, but he admitted that can be difficult at times.
‘From a grower’s perspective, if smoke around the vineyard is caused by a wildfire, there is little that can be done to avoid damage to the harvest’, Mark said.
‘However, we have been communicating with land management agencies in Victoria and Tasmania over the past couple of years about the timing of controlled burns, which are often conducted during late summer or early autumn – coinciding with the ripening period of grapes. While we are aware of the pressures facing land management agencies, we are trying to work with them to minimise the presence of smoke around vineyards during the growing season’, Mark said.
Past research has revealed that most winegrape varieties are highly sensitive to smoke taint from veraison right through to harvest. As the season progresses, grapes become less susceptible but smoke taint remains a danger.
A common question is, ‘How much smoke is enough to cause damage to vines?’
‘The answer is not yet clear. In addition to our knowledge about the damaging levels of smoke being dependent on the stage of grapevine growth and development, we know that other factors play a role, such as the grape variety, the concentration of smoke around grapevines, the duration of exposure to smoke, and the concentration of volatile phenol compounds in the atmospheric smoke itself’, Mark said.
While Mark said that there are no rules of thumb when assessing the risk of smoke taint, growers who have experienced smoke in the vineyard with visibility of less than 2–5km for a day or more post-veraison may have an increased danger of issues appearing in the finished wine.
‘After the smoke event has passed, if grapes are close to commercial harvest, pick the grapes quickly by hand, keeping the harvest as cool as possible. Most smoke taint-related compounds are located around the grape skins, so be careful to maintain the integrity of the hand-harvested fruit. Remove leaf material in the harvest and leaf pluck to help remove any ash that has settled on the grapes’, he said.
An effective means of assessing the likely risk of smoke taint is to conduct a small-lot fermentation, or consider sending grape samples for analysis of smoke taint indicator compounds.
For the AWRI’s small lot fermentation method click here
Note that fruit samples from a Phylloxera Inclusion Zone or a Phylloxera Restricted Zone require a Plant Health Certificate. For more information about PHC, contact a DPI Victoria Plant Standards Officer on 136 186 or email email@example.com
For more information contact Adrian Loschiavo, GWRDC Program Manager, firstname.lastname@example.org