By Glen L. Creasy, Sabrosia Winegrowing Services, France
Grapevines are an amazingly versatile plant. They survive in many and varied climates, they can be cut back and trained in many different ways (on a yearly basis if need be), and they produce a fruit that is made into a wide range of products that make up part of our daily diets.
You can find evidence of their adaptability by looking to the past: in their natural state, vines use sturdier plants like trees for support, growing rapidly up through the shady understory to the tops of the trees where there is plentiful light for making fruit. During the dormant season you can see how the canes of the wild grape (Vitis riparia in this case) over-run the tree it’s using for support.
Humans took a liking to the sweet/sour berries and eventually started domesticating the plant around the end of the Western Roman Empire (400AD). We began to plant vineyards specifically for the fruit, either to eat fresh, for juice, to dry or let ferment into wine.
With our influence, the way a vineyard looks has changed through the centuries, from high-density planting with only enough room to walk between the vines (most efficient when all the work was done by hand), to vines organised in tightly packed lines of vines, with enough distance between them for a horse to travel.
To keep the vines from getting in the way of traffic in the vineyard, their shoots were trained to a post, or to a wire strung between posts, creating the rows of vines that we’re familiar with seeing today.
The distance between rows of grapevines has tended to get bigger in more modern times due to the introduction of machinery, and because more planting was done in areas where land was easily obtained and plentiful. Today, the management of grapevines can be highly mechanised, though the personal touch is still necessary for a premium product.
Grapevines still have more to offer, however. The effects of climate change are already being felt in the industry (see article 1 and article 2), contributing to the development of new grape growing areas, such as in England and the south of Chile. But this is also resulting in challenges in existing production areas, such as Australia and Spain where the higher temperatures and lesser rainfall make it tougher for the vines to keep producing fruit of the expected quality, and the more frequent extreme weather events make it riskier as a business.
So what can we do with the grapevine to meet these challenges?
Grapevines as a family have a lot of diversity in them – many have tolerance to a wide range of diseases that current, popular, grapes don’t. We can take advantage of this reservoir of genetic material to produce new types of grapes that resist the heat and drought better, and which require even fewer fungicides to grow. There are a number of groups around the world that are currently contributing to developing new vine resources. For example see:
- Cornell University
- Pilzwiderstandsfähige (PIWI) International
- Julius Kühn-Institut
- UC Davis/ Prof Andy Walker
We can also change the way we grow the grapevines to manage some of these issues. For example, as temperatures rise, often the fruit develops higher levels of sugar. If the fruit is to be made into wine, this means the wine will have a higher percentage alcohol, lowering wine quality and reducing the number of situations where it’s appropriate to drink it.
Vineyard managers can trim the vines during the growing season to slow the accumulation of sugar in the fruit, while still maintaining other components that contribute to wine quality. The New Zealand wine industry is at the forefront of a programme, for example the Lighter Wines Programme, which aims to develop high-quality lower-alcohol wines. These techniques could be adapted to other parts of the world, for example, to decrease the rate of ripening as climate change causes temperatures to rise, or reduce the amount of water vines need.
Aside from embracing new disease-resistant grape varieties and changing the way we grow the vines, the next biggest change will probably be through the use of robots.
As with all horticultural crops, labour is a key component to grape production – and not just anyone can step in and tend the vines! The workers need to be skilled to get the best performance, length of life and quality out of the vineyard, and there can be a shortage of qualified people in areas where many grapes are grown.
The judicious use of robots, particularly when it comes to monitoring and managing pests and diseases in an environmentally friendly way, could go a long way toward reducing production costs while maintaining vine health, productivity and product quality.
These positive improvements present exciting possibilities, and those knowledgeable about grapevines and their management are ready for the challenges that the future brings to ensure the production of high quality grape products.
Glen Creasy is a Viticulturist at Sabrosia Winegrowing Services, Montpellier, France. The second edition of his book Grapes, co-authored with his father Leroy Creasy, is recently published in CABI’s Crop Production Science in Horticulture series.