08.18.2011  
 

California Tests New Wine Types

Petit Verdot, Malbec and other varieties suggested for San Joaquin Valley wines

 
by Jon Tourney
 
QR Code vineyard grape
 
Phase 2 variety field trial block at Kearney Ag Center in Fresno County is planted with 55 varieties. QR code tags placed in the block for Grape Day 2011 allowed attendees with smart phones to view information on specific varieties. Photo by Jon Tourney
Parlier, Calif.—Petit Verdot, Tannat, Malbec and Durif (Petite Sirah) can produce high-quality grapes and wine in the San Joaquin Valley, according to a field trial of 20 red winegrape varieties at the University of California’s Kearney Agricultural Research and Extension Center (KAREC) in Fresno County.

Results of this Phase 1 variety trial, an update on a newer Phase 2 field trial with 55 varieties, and development and introduction of new nematode-resistant rootstocks were highlights of the biennial Kearney Grape Day held Aug. 16 by UC Cooperative Extension. The program was organized and hosted by UC Davis extension specialist Dr. Matthew Fidelibus and Fresno County extension viticulture advisor Steve Vasquez.

UC Davis Cooperative Extension viticulture specialist Dr. Jim Wolpert and viticulture research associate Dr. Mike Anderson established and conducted the field trials to evaluate winegrape varieties for quality and economic suitability for production in the San Joaquin Valley. The trials had two main purposes: First, evaluate characteristics such as color, tannin, acid and sugar content. What can these add to blends for popular varietal-labeled wines to differentiate brands and enhance competitiveness for California appellation varietal wines?

Second: Identify newly available cultivars that grow well in the San Joaquin Valley, which could potentially stand on their own as varietal wines. The trials were funded by the American Vineyard Foundation (AVF).

Phase 1: Varieties and data

The Phase 1 trial block was planted in 2003 with 1103P rootstock, budded in 2004 with 20 red varieties: Aglianico, Carmenere, Cabernet Sauvignon (for comparison), Cinsaut, Durif (Petite Sirah), Freisa, Grenache Noir, Malbec, Montepulciano, Petit Verdot, Refosco, Souzao, Syrah, Tannat, Tempranillo, Tinta Amarella, Tinta Francisca, Tinta Madeira, Tinto Cao and Touriga Nacional. Research and grower trials have looked at some of these before but merited a second look, using new trellis methods and irrigation schedules. This trial included different clones that became available more recently.

Viticultural data was collected for the 2007 through 2010 seasons, including yield at harvest, cluster weight, berries per cluster, berry weight, number of clusters per vine, clusters per vine with rot or shrivel, shoot number, clusters per shoot and pruning weights. At harvest, measurements were taken for Brix, TA, pH, and for total anthocyanin and total tannin, using the Adams-Harbertson method.

The four best-performing varieties were identified based on economic, chemical and sensory considerations. Yields had to be a minimum of 8 tons per acre to be economically viable for growers. Brix target for harvest was 24.0. In 2010, harvest occurred from Sept. 9 to Oct. 20; 11 varieties were harvested within 0.5 Brix of the target. Good acidity and pH, color, tannin and phenolic content were also important factors.

Constellation Wines' Mission Bell Winery in nearby Madera donated services to make wines from selected varieties that produced sufficient, useable fruit from the 2008 through 2010 harvests. A tasting of 2010 wines produced from the trial was held in May.

Wolpert summarized: “Petit Verdot was one of the varieties we particularly liked from the trial. It produced yields of about 12 tons per acre. The yield-to-pruning weight ratio was a bit higher than we’d like, but the wine was fantastic, with good color, tannin content and varietal character.”

Some San Joaquin Valley wineries and growers already have begun planting and increasing acreage of Petit Verdot; they expect it to become known as a varietal wine in the future. The clone tested was ENTAV-INRA 400 from France.

Of the other recommended varieties, Malbec (FPS 06) tended to be lower in yield (8 tons per acre), but also produced high quality wines with good color, acidity and tannin, as did Tannat (ENTAV-INRA 474) and Petite Sirah (Durif) (FPS 03). Petite Sirah is already grown and produced as a varietal in the San Joaquin Valley by some wineries, and is blended for color in other wines. Some Tannat is also grown, primarily as a blender for color.

Wolpert and Anderson submitted a report and data about the Phase 1 trial to AVF and hope to publish an article in a research journal in the near future. Data collection was concluded in 2010: AVF has shifted funding to the newer Phase 2 trial.

Wolpert suggested that clonal trials could be a next step to determine preferred varieties comparing performance. FPS now has three clones each of Petit Verdot and Tannat, and seven clones of Malbec. A Petite Sirah clonal trial is under way at UC Davis.

Phase 2: Variety trial
The Phase 2 trial includes 55 varieties, primarily from Spain, Portugal, Italy and Southern France, certified for use in the U.S. from the UCD Foundation Plant Services (FPS) National Grapevine Importation and Clean Stock Facility. The scion varieties were field- budded in 2009 onto 1103P rootstock planted in 2008 in a 1.4-acre block.

The number of Phase 2 cultivars is a measure of the success of the FPS importation program with improved access to grapevine repositories in other countries, and improved propagation and virus screening, and elimination methods at FPS. As Wolpert explained, “The pipeline for new varieties and clones coming out of FPS has significantly shortened and increased in diameter in recent years.”

Although many varieties were selected based on their history in warmer growing locations and potential for success in the San Joaquin Valley’s climate, that is not necessarily true for every variety in the trial. Many varieties probably have never been scientifically evaluated in California before.

Wolpert admitted, “We don’t know when some of these will ripen, and we have no idea what they will do.” The block is planted with three varieties in each row. Wolpert pointed out, “Each variety is on the same rootstock, the same trellis, the same irrigation and fertility programs, but as you look down the rows, you can see very different growth patterns and vigor.”

Several varieties showed impressive, healthy clusters and good productivity. The 2011 vintage will be the first year that fruit will be harvested for data purposes, but no wines will be made until the 2012 harvest. Fidelibus, who is conducting other vine research projects at KAREC, will take over as the lead researcher for the trial after this season.

Varieties in the Phase 2 block are listed below, by country of origin and white or red variety.

Italy
Whites: Arneis, Bianchetta Trevigiana, Biancolella, Coda di Volpe, Cortese, Erbaluce, Falanghina, Fiano Forastera, Greco di Tufo, Malvasia Bianca, Moscato Giallo, Perera, Picolit, Ribolla Gialla, Tocai Friulano, Trebbiano Toscano.

Reds: Bonarda, Ciliegiolo, Corvina Veronese, Mammolo, Rondinella, Sagrantino, Schioppettino, Vespolina.

Spain
Whites: Albillo Mayor, Albillo Real, Parellada.

Reds: Garnacha Tinta, Graciano, Juan Garcia, Morrastel, Prieto Picudo.

Portugal
Whites: Alvarinho, Arinto, Viozinho.
Reds: Donzillinho, Mourisco de Semente, Periquita, Trincadeira Preta.

France

Whites: Biancu Gentile, Marsanne, Petit Manseng, Rousanne.

Reds: Arinarnoa, Caladoc, Carmenere, Counoise, Ederena, Marselan, Nielluccio, Segalin, Semebat.

The Phase 2 block includes two other red grapes—Pinotage from South Africa, and Plavina from Croatia.

Peter Cousins rootstock trial
 
USDA-ARS grape breeder Peter Cousins discusses a rootstock field trial at Kearney Ag Center that produced three new nematode resistant rootstocks released in 2010. Photo by Jon Tourney

New nematode-resistant rootstocks
Dr. Peter Cousins, grape rootstock breeder and geneticist with the U.S. Department of Agriculture—Agricultural Research Service with Cornell University, Geneva, N.Y., is performing rootstock field trials at KAREC with new rootstocks bred for resistance to root-knot nematodes. Nematode-resistant rootstocks Freedom, Harmony and Dog Ridge are traditionally used in the San Joaquin Valley.

Cousins explained: “The root-knot nematode is the most important root pest in the U.S. in terms of acres of vineyards, and the San Joaquin Valley has the most vineyard acres with potential risk. Although Freedom and Harmony are good nematode-resistant rootstocks, aggressive new populations of root-knot nematodes have developed that can feed on and damage them, so we need a second-generation resistant rootstock.”

Cousins’ breeding program makes crosses from a variety of potentially resistant grapevine sources and screens from 4,000 to 6,000 of the seedlings produced each year. Seedlings that are exposed to nematodes in greenhouse trials and demonstrate both nematode- resistance and good horticultural characteristics are then selected for field testing. The new rootstocks evaluated in field trials at KAREC are all grafted to Syrah.

Rootstocks planted in field trials at Kearney in 2005 resulted in release of three new rootstocks to nurseries in the fall of 2010 that are resistant to aggressive root-knot nematodes. Matador and Minotaur are both derived from the controlled hybridization of the Vitis hybrid rootstock 101-14 Mgt (seed parent) with the Vitis hybrid rootstock selection 3-1A (pollen parent). These selections have ancestry from Vitis mustangensis hybrids, identified as a source of resistance to aggressive root-knot nematodes.

Kingfisher is derived from the controlled hybridization of Vitis hybrid rootstock 4-12A (seed parent) and Vitis riparia (pollen parent). As with all new vine materials introduced, it will take time for nurseries to propagate enough material to make significant quantities available. Cousins advised growers initially to try the rootstocks with just a few vines, evaluate how they perform and influence yield and grape and wine quality before planting large blocks.

QR codes
A technological innovation was introduced at Grape Day 2011 for information exchange: Quick response (QR) codes were posted at presentation locations during the morning field tour. Attendees whose smart phones had code-scanning applications could scan QR codes to view and store information from technical posters in the field and speaker contact information.

Tags with QR codes also were placed on vine rows and individual vines so that attendees could obtain more detailed information about specific grape varieties in the Phase 2 field trial. Fidelibus and Vasquez have been exploring the use of new technologies, social media and blogs to provide more extension information for the grape and wine community. They received funding in 2010 and 2011 from AVF for a study, “Developing and Evaluating Social Networking Tools for Viticulture.”

Fidelibus wrote in the Grape Day program booklet: “Providing useful, timely information is always our goal in extension, so we’re planning to make more use of QR codes at field days and meetings, beginning with Grape Day.”

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