Virginia Growers Reveal Results of Trials

Grapevine diseases, pests and new research—plus ways to handle possible frosts

by Linda Jones McKee
wine grapes virginia trial conference meeting annual
Matthieu Finot, winemaker at King Family Vineyards; Kevin Goolsby, vineyard manager at Tarara Winery; and Tremain Hatch, viticulture extension research associate at Virginia Tech, speak as part of the Winemakers Research Exchange during the Virginia Vineyards Association's winter technical meeting.
Charlottesville, Va.—Temperatures in the 70s, bright sunny skies, daffodils in full flower and cherry blossoms opening; the weather was much too nice Feb. 24 and 25 to be inside for hours of talks in darkened rooms lit only by projected images of insects and grapevine trunk diseases. Nevertheless, nearly 300 grapegrowers and winemakers spent those two days listening to talks about a variety of grapegrowing challenges at the Virginia Vineyards Association’s annual winter technical meeting in Charlottesville.

While what researchers have learned about grapevine yellows and grape root borers is important information, the session that had the most immediate relevance to anyone growing grapes in the Mid-Atlantic region had the title “Potential of Sprayable Frost Protection Products and Recent Research Results.” Dr. Michela Centinari, assistant professor of viticulture at Penn State University, began her talk by saying, “When we get these crazy temperatures, growers start to get worried.”

She continued, “We had an unusually warm March in 2016, but when it got cold in April, Pennsylvania vines were not at bud break.” But Virginia growers remember distinctly that their grapes were farther along April 6, when the temperatures dropped below freezing and then fell to 22° F on April 9, 2016. Varieties such as Chardonnay and Viognier sustained significant damage.

Centinari briefly mentioned more traditional techniques for dealing with frosts, such as wind machines, smudge pots and the more expensive over-the-vine high tunnels. She then focused her remarks on a two-year study of two sprayable frost-protection products, Amigo oil (a vegetable-based oil from Loveland Products Inc.) and KDL (Potassium Dextro-Lac, a potassium fertilizer from Agro-K), which were tested on two sites. The first site, located in State College, Pa. was planted with the hybrid varieties Noiret and Traminette, while the second site, in Lewisburg, Pa., was a vinifera vineyard planted with Lemberger and Riesling.

The objectives for the two products were somewhat different. For the Amigo oil, the goal was to find out if the oil consistently delayed bud break in vinifera and hybrid varieties without impacting yield components, fruit composition and perceived wine quality. The Amigo treatment, at a 10% concentration, was applied once during the dormant season to delay bud burst, which reduces the chance of a damaging frost event. KDL, on the other hand, was applied within 24 hours before a predicted frost event to increase the vines’ freeze resistance; the objective was to see if the product provided frost protection to young grapevine shoots.

The project results showed that Amigo oil application did delay bud break, especially for the vinifera varieties. However, the Amigo-treated vines had a higher bud mortality, and a subsequent reduction in yields from lower numbers of berries and lower cluster weights. By the time of harvest there were no differences in fruit composition and wine sensory evaluation in wines made from the control, Amigo oil or KDL treated grapes.

During the two years of the study, there was one major frost event; it occurred May 23, 2015, at the State College site, where the temperature dropped to 27.5° F on Noiret and 26.5° F on the Traminette vines. Because the frost was late in May, the buds were already open, and nothing helped the reduction in yield. Centinari did note that there was more damage on VSP vines than on vines trained to a high-wire cordon. She also suggested that at sites with a lower risk of spring frost, growers might prefer to use a product that is sprayed within 24-36 hours of a frost event rather than one such as Amigo oil, which is applied months ahead of a potential event. She closed with the comment that the best alternative may be for growers to double-prune their vines.

Organic? Sustainable?
Can growers achieve those goals in Virginia? Just ask Thomas Jefferson; he discovered just how tough it is to grow grapes in the Virginia climate. It’s hot and humid in the summer, has spring and fall frosts, cold temperatures in the winter and a wide variety of insect pests and diseases to deter all but the most stubborn growers. It’s difficult enough to produce wine grapes when using modern techniques and sprays, but there are some people who are trying to establish organic vineyards and wineries even in those conditions.

Karl Hambsch established Loving Cup Vineyard and Winery in North Garden, Va., in 2007 with the firm belief that growing grapes organically could be done in Virginia. Knowing that he wanted to put in an organic vineyard, Hambsch first decided on the characteristics he wanted in his grapes, including disease resistance, open clusters, tolerance for copper and sulfur, and the wine style those grapes would make. He then selected the varieties to plant. He discovered that cold-tolerant grapes often were also disease resistant, so several of the varieties he planted are cold-climate grapes, including Marquette and Corot Noir. Currently under trial are two Elmer Swenson hybrids, Brianna and Kay Gray, and two New York grapes from Cornell University’s breeding program, Arandell and Valvin Muscat.

The major challenges once the vines were planted are dealing with diseases, insects and weeds.

Because he doesn’t use synthetic sprays, Hambsch pursues a sanitation program with vigor: he looks for and then removes leaves and berries with disease as quickly as possible during the season and while pruning in winter. He also carefully manages the canopy of his vines with de-suckering, shoot thinning and positioning, and 100% leaf removal in the fruit zone, and then sprays with organic sprays. Those sprays, he notes, are preventative but not cures for the many diseases he finds in his vineyard: black rot (which he describes as “the Achilles heel of organic grapegrowers”), downy and powdery mildew, sour and bitter rot, phomopsis, anthracnose, tar spot, Esca and numerous others.

Japanese beetles are especially difficult to control. Since Hambsch doesn’t use insecticides, he tries to encourage beneficial insects such as lace wings, ladybugs, praying mantis and spiders. For weed control, he has tried flaming (which works best when seeds are newly germinated), roto-tilling under the vines, hand hoeing and weeding; this summer he may try paper landscape fabric.

Asked why he chose not to be sustainable rather than organic, Hambsch replied that he wanted “to build systems around our principles.” And at this point, he can label his wines “Made with organic grapes.” According to Wines and Vines Analytics, Loving Cup Vineyard and Winery currently produces 500 cases annually.

Ed Boyce, owner of Black Ankle Vineyards in Mt. Airy, Md., opened his talk by noting, “We attempted to be organic/Biodynamic in our first crop year (2005), but failed spectacularly. We lost 60% of the crop to black rot and Japanese beetles.” Now his goal is “to push sustainability as much as we can within the context of growing the best possible wine. We want to get the grapes ripe and make the best possible wine.”

The most important piece of sustainability is the vineyard floor, according to Boyce. He believes that herbicides and artificial fertilizers are more harmful to the soil and to wine quality than vineyard sprays. Consequently, he uses a weeding machine to control weeds and improve the air/soil “interchange,” and sprays some fungicides and for Japanese beetles. “We haven’t been able to eliminate all chemical products from our spray program without endangering yields, fruit quality and vine health,” Boyce said. “Black rot is what keeps Black Ankle from being organic.”

Boyce also would like to see a concerted research effort to solve the Japanese beetle problem. “Can we figure out why they like grapevines so much, then do something to make them less attractive?” he appealed. “They have a pheromone to attract other beetles, do they have one to warn others of danger? Can we synthesize it?”

Black Ankle Vineyards now has 42 acres of vinifera grapes and produces 7,500 cases annually. The winery and tasting room were built using straw bale construction to reduce heating and cooling costs; an 86 kW solar array provides 100% of their power; the tractors run on biodiesel, and the parking lot has six electric car chargers (three are Tesla-specific, three are for other plug-ins).

Va. winemakers conduct vineyard research

It’s not every grapegrowers’ meeting that spends an afternoon tasting wines from vineyard experiments. Almost all attendees at the conference stayed through the afternoon sessions Saturday in order to participate in those tastings and learn the results of the latest vineyard/winemaker research. Winemakers in the Monticello AVA came together in 2014 to create a research collaborative among wineries along the Monticello Wine Trail.

In 2016 the Winemakers Research Exchange (WRE) received funding from the Virginia Wine Board to take the Monticello AVA project statewide. The WRE hired Michael Attanasi, a recent master’s graduate from the University of California, Davis, to run the program, organize projects and collect samples and lab data. The results of the various winemakers’ research projects are then summarized, synthesized and published.

Kevin Goolsby, vineyard manager at Tarara Winery in Leesburg, Va., presented the results of research that he and Jordan Harris, Tarara’s winemaker, did on the impact of removing the four most basal leaves from Cabernet Sauvignon vines at 30% bloom. Another section of Cabernet vines was not leaf-pulled at bloom; both blocks were leaf-pulled at véraison, and all other vineyard and fermentation practices were the same. Removing leaves at bloom slightly reduced berry weight, cluster weight, Brix and yield, while grape phenolics and total acidity were slightly increased. Wine produced with leaf removal at bloom had lower ethanol, color intensity and tannin.

Tremain Hatch, viticulture extension research associate at Virginia Tech and consultant to his family’s winery, Zephaniah Farm Vineyard in Leesburg, Va., discussed the work that he and Bill Hatch, Zephaniah’s winemaker, did on the impact of a desiccation spray on the chemical and sensory profiles of Chambourcin grapes and wine. One section of Chambourcin vines was sprayed with a potassium bicarbonate desiccant, and another section was not.

The desiccation spray was applied at the beginning of véraison and then weekly for a total of four sprays over four weeks. The fruit from both sections of the block was harvested and processed on the same day, and all treatments were identical. The desiccation treatment slightly concentrated berry components, lowered the color intensity and slightly lowered the tannin and anthocyanin content in the wine. Not many differences were found in the wines.

Matthieu Finot, winemaker at King Family Vineyards in Crozet, Va., conducted a study on the impact of different crop adjustments on yield, juice and wine chemistry, phenolic and color profiles, and sensory characteristics of Merlot. The four treatments in this trial were done in one vineyard block: 1) two control rows; 2) two rows sprayed with RG 1950 desiccant spray four times over four weeks beginning at véraison; 3) two rows with clusters dropped at véraison down to one cluster per shoot, and 4) two rows with clusters pinched at approximately 20° Brix. All other treatments, through vinification, were the same.

The week before harvest, from Sept. 26 to Oct. 2, 2016, the vineyard received 6 inches of rain. Finot reported, “The rain ruined the desiccation trial.” Prior to the rain, the desiccation sprayed grapes had faster ripening kinetics and lower average berry weights. At harvest, Brix and pH were not very different, but total acidity was higher in the treatments. Yield was reduced by all treatments, and no differences were apparent in wine chemistry. Finot would like to repeat the study, but with more cooperation from the weather.

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