Growing for the alcohol-free market

One particularly interesting discussion was around the growth of the alcohol-free wine sector, and the important role that vineyard agronomy can play within this.

While great progress has been made in producing good quality alcohol-free beers in recent years, the wine sector has faced more of a challenge, not least because winemakers have to replace 11%-14% alcohol volume instead of 4%-5%, while meeting the quality characteristics consumers want.

It is often assumed that all of the work required to produce a low, or zero-alcohol wine occurs within the winery, but experts say that to do it well, the process should begin in the vineyard.

For a good quality, flavoursome, low/no-alcohol wine, the aim is to achieve phenolic ripeness with the lowest sugar levels possible. This, experts say, can potentially be achieved with aggressive canopy trimming (the canopy drives sugar production), early bunch exposure to aid ripening, and targeted nutrition to achieve phenolic ripeness.

The approach appears to be working for some in New Zealand, and with the low/no-alcohol wine sector becoming increasingly important in the UK, albeit from a low base, it may be worth looking at in more detail here.

Fermentation in the vineyard

The concept of “terroir” has been taken a step further by some NZ growers, who are now producing wines where the entire primary fermentation is carried out among the vines, rather than transporting grapes out to the winery, where the ‘winery’ yeasts will dominate the fermentation.

The theory is that fermentation will then be dominated by the natural yeasts present on the grapes from that site, making the finished product even more reflective of its place. Peak fermentation temperature is typically lower when vats are outside, and the two factors combined are said to help produce a smoother, softer, rounder flavour than indoor winery fermentation. Even to a not-very-discerning palate, there was a difference in the taste and mouth feel of the finished wine.

Vineyard fermentation will not be for everyone, but as so much wine is sold on the back of its provenance, the concept is certainly very interesting and may be for some UK growers to explore.

Shaking out botrytis

Botrytis is an ever-present threat in many wine-growing regions, but growers in New Zealand are seeing some promising results from a new technique that vibrates the canopy post-flowering to shake off any loose flower caps and other debris that may become stuck to developing bunches and increase the risk of latent infection. This is also followed with a low dose of copper.

In the UK, vine canopies may not be large enough by this stage in the season for vibration techniques to be as effective, but some growers are already trying a similar approach by using an air-assisted sprayer to blow debris out of the canopy.

It is by no means the whole story for Botrytis control, but if it is proven to help reduce risk, then having a low-impact, non-chemical tool in the armoury certainly appeals, to both organic and conventional growers alike.

And finally…

Researchers at Lincoln University near Christchurch have identified a community of microorganisms (fungi and bacteria) that, when living in the vascular system of the vine, appear to confer resistance to grapevine trunk disease (GTD).

They did this by analysing 70 woody trunk tissue samples from both diseased grapevines, and vines that had escaped GTD despite being surrounded by know infection. DNA analysis was then used to identify and compare the microorganisms present in diseased and ‘GTD escape’ samples.

The team is now investigating whether grapevines could somehow be inoculated with these beneficial microorganisms to provide a natural, sustainable option for GTD control/suppression. The work is all still at an early stage but is definitely something to watch for the future.