What Are Grape Clones?

Two pieces of live vine are being put together like puzzle pieces
Grafting rootstock/Photo by Strike Photography

The term “grape clone” might bring to mind images of scientists hunched over petri dishes, but grape growers have selected and propagated their best vines for centuries.

A grape clone is a cutting taken from an existing grape vine that’s grafted onto rootstock. The vine is chosen due to specific traits a grower wants to reproduce like increased disease resistance or fruit quality. Because this cutting came directly from another vine rather than the result of two plants crossbreeding, the cutting is genetically identical to its “mother vine.”

“A lot of people think we’re doing a GMO thing, but it’s actually more of a field selection,” says Marta Kraftzeck, winemaker for Scheid Family Wines in Monterey County, California. “Somebody was strolling through the vineyard one day and thought, ‘Wow, this vine looks really different than this other vine, so I’m going to try and reproduce it.’ ”

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Why do winemakers use grape clones?

“It’s expensive to plant grapes, whether it’s here or anywhere else in the East or the West,” says Alice Wise, an extension agent at Cornell Cooperative Extension of Suffolk County in Long Island, New York. “It takes at least several years, sometimes longer, [for a vine to mature] so you really can’t afford to waste your time and money on something that doesn’t perform well.”

“If I’m talking about what clones someone might plant, my first question is, ‘Where is the wine going?’ ” says Nick Hoskins, director of viticulture at Riversun, a plant and grapevine nursery in Gisborne, New Zealand. “A $20 or a $50 bottle makes a big difference. I would also have a mix of clones because they perform differently in different years. You want to give yourself the best chance you can to make a good wine each year.”

According to Wes Hagen, winemaker for J. Wilkes Wines in Santa Barbara, California, clones can be temperature sensitive, which makes some more suitable for certain climates. Hagen says that some clones are known for deep color, while others have better disease resistance. He also pays attention to the density of a vine’s foliage, which affects ripening and yield size, and can impact quality. And, of course, the final wine has to taste good.

Once a grafted vine matures, factors like weather, farming practices and soil type, among others, can influence the final outcome of the wine. It’s may be better to think of clones in terms of tendencies rather than guarantees.

“You have to plant something, and you have to engage with the clonal system to plant a commercial vineyard,” says Hagen. “I’m not saying [the] clone doesn’t matter, but it is a cog in an incredibly complicated system.”

“You can make all the claims you want about a clone giving you structure or spice, but it’s still going to react to your site climate, your farming practices, use of pesticides, herbicides [and] fungicides, whether you irrigate or not, the development of the root system, how deep the roots go, your choice of rootstock. All of these things,” says Peter Neptune MS, founder of the Neptune School of Wine in Orange County, California.

Rows of vines on mounds of dirt
Grafted vines at Riversun’s nursery/Photo by Strike Photography

Where do vineyards get their clones?

Confusion about the word “clone” is why Nancy Sweet, historian for Foundation Plant Services (FPS) at University of California, Davis, says she and her colleagues refer to different clones as “selections.”

FPS is one of the main avenues that grape growers in the U.S. can import clones from outside of the country. Scientists test and treat the cuttings for diseases before they’re released to growers. This process can take years. Each clone that comes through FPS is given a reference number, like Chardonnay clone FPS 04.

American researchers began to look for new grape clones during the mid-20th century to diversify U.S. vineyards, and cuttings were imported by FPS from all over the world.

Other organizations also catalog clonal selections, like the French governmental research collective that licenses only domestic selections under the trademark ENTAV-INRA. Similar clones can have more than one number if they were brought into the U.S. prior to the creation of ENTAV-INRA.

An example is Pinot Noir clone FPS 38, which is reportedly the French clone 459. However, this is unproven because it was imported before ENTAV-INRA existed. Thus, it isn’t certified by the French government.

Tall rows of vines with grass in between
Rootstock vines ready for harvest at Riversun/Image by Strike Photography

What are some popular grape clones?

There are different clones available for just about every grape variety. Three of the most planted varieties are Chardonnay, Pinot Noir and Cabernet Sauvignon. With thousands of clones available, many factors affect what gets planted in a vineyard.

The Wente clone is the most well-known Chardonnay clone in California because Wente Vineyards in Livermore was one of just two commercially viable Chardonnay vineyards to survive Prohibition. Many vine cuttings have been taken from it over the years. There are multiple separate clonal lines that can be traced back to it that include FPS 04, FPS 17 and FPS 67.

Prior to being acquired by FPS, the Wente clone was known for a high percentage of undersized, underripe berries in each cluster. When FPS received some Wente cuttings in the 1960s, scientists eliminated its viruses, and the healthy clonal selection became referred to as clone 4.

When the viruses were removed, it also curbed the tendency toward undersized berries. Today, the clone is known for late-ripening, heavy grape clusters that lead to high yields while still producing reliably good-tasting wine.

In the 1980s, winemakers in Oregon sought clones that would succeed in their vineyards, so they imported a group of French Chardonnay and Pinot Noir cuttings that came to be known as the Dijon clones. These are now widely planted throughout the U.S.

Two common Chardonnay clones are 76 and 96, and three of the most common Pinot Noir Dijon clones are 667, 777 and 115. In general, the Dijon clones are known for smaller berries, earlier ripening and very expressive aromatics.

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The DNA of grape vines change as they grow in different environments. In particular, Pinot Noir is prone to mutations. Several famous Pinot Noir clones have been brought to the U.S., like the Pommard clone from Burgundy, known for structured tannins and intense color, and the Wädenswil clone from Switzerland, which offers large clusters and refreshing acidity.

Both clones have multiple selections available from FPS and required different amounts of virus treatment. Others were submitted from existing California sites, like the elegant Swan clone (FPS 97) and the rich Mount Eden clone (FPS 37), both named for their source vineyards.

There are also several different common Cabernet Sauvignon clones used in the U.S.

FPS 07 and FPS 08, which were cut in 1965 from different parts of the same vine in the Concannon Vineyard in Livermore, California, are thought to have originated in Bordeaux. They’re known to make quality wine at high yields and have been widely planted in California since the 1970s. The French clone 337 (also known as FPS 47) is also popular because it typically produces small berries with a balanced tannin and acid structure for aging.

With fluctuating temperatures and erratic weather patterns, clones may play a significant role to address these changes.

“One of the interesting things for the future is finding the clones that do better in different regions and climates,” says Dave Nagengast, vice president of winemaking at Scheid Family Wines. “As it’s getting warmer, [change is] moving rapidly, but not overnight. We just have to adjust.”

“Will Pinot Noir adapt to warmer climate conditions?” asks Neptune. “That’s going to be concurrent with whatever root stock we’ve chosen because rootstocks are generally chosen to adapt to the temperature of the soil, the soil’s water retaining capability, etc. The plant scientist is going to be on the lookout for mutations that are heat-resistant, drought-resistant and disease-resistant.”

Regardless, clonal selection is just one tool that a winemaker can use, so it’s important to maintain perspective.

“It’s just fermented grape juice, and if you just want a nice drink, you don’t have to think about this stuff,” says Hagen. “It’s taken me 25 years in the wine business to understand how complicated clones are.”

Published on November 13, 2019
Topics: Wine and Ratings


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