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New PD-Resistant Wine Grape Varieties Named and Released

Patents Filed for Walker-bred Cultivars Developed at UCD
by Ted Rieger
December 03, 2019
UCD viticulture professor and grape breeder Dr. Andy Walker developed the five PD-resistant wine grape
varieties with research funding from the CDFA PD/GWSS Board. Photo: Ted Rieger

The University of California, Davis (UCD) Office of Research’s Innovation Access unit recently informed the California Department of Food and Agriculture (CDFA) of the official release of five new Pierce’s Disease (PD) resistant grapevine varieties developed in the breeding program of UCD viticulture professor and grape breeder Dr. Andy Walker.

The five releases include three red wine grape selections and two white wine grape selections that have repeatedly shown strong resistance to PD in greenhouse and field trials, and have shown high fruit quality and high wine quality across several vintages and in wine tastings. These five selections are the results of a multi-year research and breeding project largely funded through the CDFA Pierce’s Disease and Glassy-Winged Sharpshooter (GWSS) Board.

Patent and Licensing Activity

Plant patent applications were filed with the United States Patent and Trademark Office on November 5, 2019 for each of the five varieties and the name given to each variety by Walker. Once UCD receives the official notice of filing, the university will begin to market and license the grapevines. UCD Research Innovation Access provides services that connect university research to the marketplace and is focused on protecting and commercializing intellectual property and fostering entrepreneurship. UCD informed CDFA of its plans to protect and license the five new PD-resistant varieties.

An announcement of the release of the PD-resistant cultivars will be sent by UCD Foundation Plant Services to commercial grapevine nurseries participating in the CDFA Grapevine Registration and Certification Program. Non-exclusive licenses will be made available to CDFA licensed nurseries that participate in the Registration and Certification Program. UC will consider licensing nurseries outside of California if they are licensed to sell clean plant stock and participate in their state’s grapevine registration and certification program (if one exists). The license agreement will include a one-time license issue fee of $250.00 and a royalty of $1.00/grapevine sold.

Variety Development and Potential Uses

Walker and his lab have been traditionally-breeding wine grape varieties of Vitis vinifera with native American Vitis species that carry PD-resistance genes. The five new releases carry a PD-resistant gene from Vitis arizonica. Walker uses traditional breeding methods that involve the backcrossing through several generations of vine crosses to progressively increase the V. vinifera parentage and characteristics to as high as 97% within the final resulting cross. Each generation carries resistance genes.

Wines have been produced from field trials of these cultivars and have been evaluated by UCD staff and wine industry representatives at several tastings. In addition to UCD campus field trials, field trials with PD-resistant cultivars have been conducted, or are ongoing, in Napa Valley, Sonoma County, Temecula, and Ojai in Ventura County in California; and in Texas, Alabama and Florida.

In California, these cultivars are expected to be of interest for planting at sites where PD pressure is high, such as North Coast riparian areas, or in Southern California locations where GWSS populations exist. They could be used at levels of 25% or less in other varietal wines, or as components of non-varietal red or white wine blends. In addition, PD-resistant cultivars could be highly sought and accepted for commercial use in the Southeast U.S. where growers are generally limited to growing currently available PD-resistant hybrids that do not have V. vinifera wine quality.

The five patent-pending varieties (with their breeding program index numbers) and information provided by Walker are described below.

Camminare Noir

07355-075—50% Petite Sirah, 25% Cabernet Sauvignon: This red wine grape makes wines with characteristics of both Cabernet Sauvignon and Petite Sirah. Commercial scale wines have been made from established test plots along the Napa River. This selection is early to break dormancy, bloom and ripen. It produces relatively large berries, with well-filled clusters of medium size. It has tested to be highly PD-resistant and has a 94% V. vinifera level. It has ranked highly at numerous tastings of both Davis and Napa grown fruit. Tasting descriptions include: dark red-purple in color, bright red fruit, raspberry, cherry, ripe, tannic and elegant rather than dense.

Paseante Noir

09331-047—50% Zinfandel, 25% Petite Sirah, 12.5% Cabernet Sauvignon: A red wine grape with characteristics of Zinfandel and Cabernet Sauvignon, highly PD-resistant with 97% V. vinifera. Commercial scale wines have been made from established field trials near the Napa River and from Temecula. Blooms relatively late but ripens mid-season. Medium-sized berries and large well-filled clusters. It is spur fruitful but typically has only one cluster per shoot and is more productive with cane pruning. Tasting comments include: medium dark red with purple color, berry pie, cassis, black olive, herbal, dried hay, coffee, vegetal like Cabernet Sauvignon, licorice, round, moderate tannins, and soft finish.

Errante Noir

09356-235—50% Sylvaner, 12.5% Cabernet Sauvignon, 12.5% Carignane, 12.5% Chardonnay: A red wine grape, highly PD-resistant with 97% V. vinifera. Mid-season bloom and ripening period. Highly productive with relatively large berries and loose clusters. Tasting comments include: dark red purple color, complex fruit with herbs and earth, plum, big wine, dense, rich middle, tannic yet balanced. Winemakers believe it has great blending potential with Cabernet Sauvignon and has high levels of high quality tannin.

Ambulo Blanc

09314-102—62.5% Cabernet Sauvignon, 12.5% Carignane, 12.5% Chardonnay: A white wine grape highly PD-resistant with 97% V. vinifera. Field tested in Temecula, Sonoma and along the Napa River. Blooms and ripens early. Highly productive with small to medium berries and relatively large clusters. Wines are reminiscent of Sauvignon Blanc and tasting comments include: light straw to clear color, citrus, lime, tropical, gooseberry, golden delicious apple flavor, bright fruit, slightly bitter, and textured.

Caminante Blanc

09338-016—62.5% Cabernet Sauvignon, 12.5% Chardonnay, 12.5% Carignane: A white wine grape highly PD-resistant with 97% V. vinifera. Field trials planted in Davis, and more recently underway in PD hotspots in Napa and Ojai. It has small berries, small compact clusters and blooms relatively late but ripens mid-season. The vine has medium productivity. Wines made from Davis-grown fruit have rated well and tasting comments include: light straw-gold color, floral aromas, apple-melon, lychee, pineapple, green apple, juicy, harmonious, and well-balanced.

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