AWRI offers advice on smoke taint for winemakers

The Australian Wine Research Institute (AWRI) has developed an information page for winemakers and grapegrowers that gives advice on how to deal with recent hot weather conditions and the potential for smoke taint.

The presence of smoke taint in fruit is governed by a number of factors including proximity and type of fire, intensity, duration of smoke cover, prevailing wind and weather conditions.

The timing of smoke exposure to grapevines is also important. There is low sensitivity to smoke uptake in the growth period to flowering and low to moderate risk through veraison. Beyond veraison through to harvest, grapevines can be highly susceptible to smoke taint.

The AWRI recommends grapegrowers and winemakers follow the testing regime below to ensure grapes are free from smoke taint and remain fit for purpose:

• If your region has experienced a smoke event, wait until ripening has proceeded beyond veraison before testing for smoke taint.
• There is considerable variation across a vineyard, so follow a sampling regime that takes into account topographical features of the vineyard and follow the same sampling regime when carrying out repeated sampling.
• Small-lot fermentation is highly recommended in assessing potential to produce smoke taint in wine.

The AWRI has developed a basic fermentation protocol which is available on its website. Analytical support is available and this is also summarised on the AWRI website.

The effect of extreme heat on grapevines depends on the timing of the heat event relative to the grapevine growth stage. Flowers are highly susceptible and poor fruitset may occur from a heatwave during flowering. After veraison, as grapes soften, grapes become much more prone to shrivel or sunburn. Dark-coloured grapes directly exposed to the sun may become up to 15°C hotter than the surrounding air temperature.

The information page is available on the AWRI website: www.awri.com.au.