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Responding to climate change, part three

Winemaker Roundtable

To deal with changing climatic conditions and plan for the future, can you describe a couple of key changes you have made in your viticultural practices? For example, have you adjusted vine exposition, pruning techniques, canopy management, the selection of rootstock or varieties to plant, targeted crop levels or harvesting strategies?

Bernard HervetDomaine Faiveley (Burgundy, France). My concern is more for chardonnay than for pinot noir. If you taste the 2003 Burgundy reds, from a very hot season, their evolution is like 1947. So it’s not a bad experience, and the wines will have quite a long life.

For the chardonnay, climate change is a very sensitive point. My opinion is that we have planted some clones—or massale selection—that ripen too early, and phenolic ripeness is a key point. Maybe we are protecting too much against rot, because my experience in terms of premature oxidation problems has always been better with vintages that have a percentage of rot in the must!

Lynnette Hudson, Lynnette Hudson Wine Consulting (Auckland, New Zealand). I believe that what is happening is both global warming and climate change. There is no doubt that the regularity of warming vintages is rising, but then so are the erratic weather patterns consistent with climate change.

Regarding viticultural practices that I have adjusted to deal with these new climatic conditions then, certainly crop level is one area of extreme importance. Typically less is best but I have heard of several methods such as laying extra canes initially to get through the frosts of springtime. Once fruit set is complete and if yields are high, then a whole cane can be removed, quickly reducing the yield. Timing is important: typically doing this when the berries are pea-sized gives the best results; if it’s later than that,  the impact of cane removal is lost. The cane shrivels and dies, with the benefit of crop reduction, unless the season is wet as the extra debris can encourage botrytis. I tend to rely more on estimating crop levels using bunch weight analysis and aiming for two tons per acre for pinot noir especially.

For chardonnay and riesling, canopy management varies. Both of these varieties can benefit from some leaf-shading, especially in warmer vintages, as browning of the skin increases phenolics in the resulting wine. But it’s a fine balance: leaves can prevent browning of the skins in a warmer season, but if it rains then disease pressure can increase.

As for other changes, many of them are forward predictions: i.e., replanting different clones and using different rootstocks. If replanting is considered, then obviously these things are very important. But in New Zealand many vineyards are relatively young and hence it is uneconomical to consider replanting at such an early stage.

Pietro RattiRenato Ratti (Piedmont, Italy). For example, to reduce alcohol levels we have adopted a few viticultural practices. The most important has been to increase the grass on the ground. This delays the sugar translocation into the grapes, allowing for slower ripening. For the same reason we are also delaying green harvesting. Higher grass is also important for reducing sunburn and mildew attacks.

Looking to the larger scenario of the entire Langhe area, we can see more options to plant noble grapes like nebbiolo. Since nebbiolo has a long ripening season, only specific micro-areas are suitable to grow it.  With a change in climate conditions and more types of wine to make (for example, sparkling wines), people are replacing vineyards of dolcetto and barbera with the more profitable nebbiolo.

Coenie Snyman, Rust en Vrede (Stellenbosch, South Africa). Rust en Vrede. As far as long-term viticultural practices go, I believe we are already well-positioned for changes in climate with our current approach. For example, we have not changed our vine exposition since we align our vine row from east to west, which is the cooler exposition. In our rich soils we still employ the weaker 101-14 rootstock to create a better canopy balance.

Our soils and roots are the best buffer against climate change, but they will be affected. We specialize in cabernet sauvignon and shiraz but have decreased plantation of merlot. We have increased our inter-vine spacing in our VSP (vertical shoot positioning) vineyards to accommodate the vegetative growth better. Cover crop and mulching practices are monitored closely to ensure proper root development, which helps to buffer changes in climate. And we also use drip irrigation on a supplementary basis and farm with using NDVI (normalized different vegetation index, a form of imagery that, among other things, helps a vineyard owner to identify and capitalize on the best vineyard blocks) as a guideline.

We still employ an open-canopy strategy with suckering and leaf-removal practices. We also pay attention to proper space during pruning and summer pruning. And we monitor leaf water pressure to manage irrigation and vine stress.

We harvest according to growth patterns with NDVI. Phenolic ripeness is our major guide for picking, and this is where we will see changes in the future. We’ll continue to treat each vintage on its own merits, trying to find the balance between phenolics, ripeness and alcohol.

June 11th, 2014 | no comments

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