Clones, Hybrids, and Crosses

This weeks' blog sounds more like a title to some type of science fiction novel, or something having to do with Dolly, the sheep, but is in fact an important part of wine study. While we don't often talk about hybrids and crosses, clones are mentioned more and more in the production of wine. If you have tried any Pinot Noir lately, you most likely encountered a reference to the clone used in the making of the wine. But, what are hybrids, crosses and clones?

Let's start with the most basic: "crosses". Essentially all grapes are crosses. A cross occurs when two varieties from the same species of vine "cross", to make a new variety. So, a cross is produced by fertilizing the flower of one variety with the pollen of another variety, thus creating a new variety. This is followed by the planting of the grape seeds that are the product of the cross-pollination. These crosses can be the result of human intervention, or natural. Most of the human made crosses have been less than spectacular, but the most notable would be Pinotage (a cross between Pinot Noir and Cinsault), or Müller-Thurgau (a cross between Riesling and Madeleine Royale - which is itself a cross between Pinot and Trollinger). Outside of Germany and South Africa, there aren't too many man-made crosses that stand out. On the other hand, natural crosses have created some of the finest wines in the world. Cabernet Sauvignon is in fact a natural cross between Cabernet Franc and Sauvignon Blanc. Recent DNA research has led to a better understanding of a grape's parentage. In her new book, "Wine Grapes", Jancis Robinson has put together the most detailed research into the subject. Her book is a "must have" for those interested in grape varieties.

Vidal Grapes at Inniskillin

"Hybrids" are the same as crosses, but different. While crosses are between two varieties from the same species, hybrids occur when two different species of vine are crossed. Originally, hybrids were done due to the fact that some American vines are quite resistant to powdery mildew. American vines are not wine grape vines (Vitis Vinifera), so by creating a hybrid, the old world wines might be more resistant to certain diseases. There aren't many successful hybrids on the market, and hybrids are actually banned in Europe for commercial wine. But hybrids are important in some other regions of the new world, in particular in North America, where vitis vinifera grape vines struggle to grow. If you have ever tasted any wines grown in the midwest, east coast, or Canada, you may recognize these hybrids: Vidal (making some of the sweet dessert wines of Canada), Baco Noir, or Seyval Blanc.

Pinot Noir clone at Melville Winery

Cloning is different from both crosses and hybrids. A Clone is defined as “a vegetative propagation of a single parent plant”, and is a process where individual vines are selected from a grape variety on the basis of certain attributes. Do to genetic instability, most of the older grape varieties have a tendency to mutate, adjusting to their location, climate, terrain, etc. As these grapes mutate, the winegrower and winemaker may notice subtle differences in the growing process, or the taste of the juice. If it is a desirable change, then the natural instinct would be to encourage that mutation to propagate. One of the best known examples is Pinot Noir. Today, there are somewhere between 300 and 1000 different clones in Burgundy alone. Today, you can go to almost any Pinot Noir vineyard, and they will tell you what clones they have planted. Many will tout their clones on the label of their bottle. “Dijon”. “Pommard” and “Swan” give indications of where the clone was propagated (While Dijon and Pommard are in France, “Swan” is named after Joseph Swan who propagated the clone in the Russian River Valley). Others are simply called, “Clone 113” or “Clone 115”. Each clone has its own style and personality, and it is up to the vineyard manager and the winemaker to determine what best suites their needs.

“Selection massale” is the opposite of cloning, where growers select cuttings “from the mass” of the vineyard, or a "field blend". If you are a believer in terroir, then the question becomes, is clonal selection a good thing, or does Selection massale better reflect the terroir of the vineyard? Your taste buds and nose will help you decide. I'd like to hear your thoughts.

Countdown to Harvest

Ampelos Vineyards

It's an important time of year in the northern hemisphere....an important time, that is, for grape growers and winemakers. If you have been to a vineyard in the last couple weeks, you probably saw a lot of little hard green berries on the grape vines. If you go back today, you may notice something has changed.

Véraison [vay-ray-ZON] is a wine term which refers to the onset of ripening. It is French word, but is used throughout the wine world. The official definition of véraison is "change of color of the grape berries." Véraison represents the transition from berry growth to berry ripening. In the northern hemisphere, véraison typically occurs anywhere from late June to mid August, depending on the climate.

Here is a short video from Adopt a Grape, discussing the importance of véraison in the vineyard.


Veraison '08 at Adopt A Grape from Adopt A Grape 2009 on Vimeo.

Following fruit set, grape berries are green and hard. They have very little sugar and are high in tartaric and malic acids. They begin to grow to about half their final size when they enter véraison. During this phase the colors of the grape change from green to red or yellow, depending on the variety. For those big on science, this color change is due to the chlorophyll in the berry skin being replaced by anthocyanins (red wine grapes) or carotenoids (white wine grapes). The berries start to soften as they build up sugars. Within six days of the start of veraison, the berries begin to grow dramatically as they accumulate glucose and fructose and acids begin to fall. If you were to look at a graph of acid versus sugar levels, you would see that véraison occurs when the decrease in acid crosses over the increase in sugar. The acids are actually being "burnt up" by the respiration of the grape berry. If you want to get into great detail on the actual science, check out "Wine Science Principles and Applications" by Ronald S. Jackson, or "Knowing and Making Wine" by Emile Peynaud. Both books are very technical.

Stoller Vineyards

Véraison, unfortunately for the wine grower, doesn't occur uniformly across the vineyard. Typically the berries and clusters that are exposed to warmth, undergo the change first, and those that are closer to the trunk and under the shade of the leaves (canopy), are last. There are things in the vineyard that can control the onset of véraison. Limited water stress and canopy management, that creates a high "fruit to leaf" ratio, can encourage véraison. So, skilled vineyard workers, who know how to thin the canopy properly, are worth their "weight in gold". On the other end, vigorous grape varieties, with lots of leaf shading for photosynthesis and water supply will delay the start of véraison, due to the vines energies being directed towards continued foliage growth and new buds. During this period the cane of the vine starts to ripen as well changing from green and springing to brown and hard. The vines begins to divert some of its energy production into its reserves in preparation for its next growth cycle. For the production of high quality wine, it is considered ideal to have an earlier véraison

Some wine growers will perform a green harvest, where less ripe bunches are removed. The idea is help concentrate all the energy into the remaining berries, which in turn, should produce more concentrated wines. There is a bit of a gamble however, namely if the remaining time between véraison and harvest experiences severe drought or excessive heat, the result could be dry berries, which produce unbalanced wine. So, when you visit the vineyard this time of year, you'll see growers checking their crop. They know that once véraison starts, they are only about 45 to 50 days from harvest. And that can be 45 to 50 days of holding their breath!

Let the countdown to harvest begin!