Dr. Andy Walker, a geneticist and professor at University of California-Davis (UC-Davis) began a research program over 20 years ago to develop new grapevine cultivars that carry resistance to the deadly Pierce’s Disease (PD) that causes over $100 million in damage each year. Dr. Walker discovered a Vitis arizonica grape variety from the southwestern United States and northern Mexico that carries a dominant gene for PD resistance. He began to cross this variety with more common Vitis vinifera grapes and now has developed five new varieties that show strong resistance to PD. These varieties have been propagated by nurseries in California with support from UC-Davis and have recently become commercially available to grape growers, several of whom are in Texas.
You might ask what is Pierce’s Disease and how is it spread. The disease is a bacterium infection that causes grapevine leaves to yellow, die, and eventually drop from the vine. This results in grape clusters that dehydrate and wither, and eventually the vine will die. Glassy-winged sharpshooters are insects that carry the disease from wet, swampy areas near creeks and ponds to grapevines as they feed on grapes. Once the insect punctures a grape or leaf with its sharp proboscis, the bacterium spreads throughout the vine and the vine dies. Currently, there is no known cure for PD and the primary methods for control are insecticides to kill sharpshooters and planting vines far away from surface water sources.
How did Dr. Walker create these new grape variety crosses? Of the 3,000 or so grape varieties used for wine production around the world, most are crosses – created when the flower of one species gets pollinated by another species, either naturally or by human intervention. Working with the PD resistant Vitus arizonica variety, Dr. Walker crossed popular Vitis vinifera varieties, like Cabernet Sauvignon and Chardonnay, to create these new grapes.
An interesting note – Blanc du Bois, a well-known white grape in Texas, is a hybrid-cross created by Professor John A. Mortensen (a native Texan) at the University of Florida. Mortensen crossed various Vitis vinifera grape varieties with native Florida varieties which had natural PD resistance. When released in 1987, Blanc du Bois became an important grape that can produce marketable wine on its own yet resist the bacterial infection of Pierce’s Disease. If you aren’t already familiar with this grape, I can personally recommend Haak Vineyards & Winery, Lost Oak Winery, and The Triple D Vineyards.
Over more than 20 years, Dr. Walker tried hundreds of crosses and ran thousands of experiments that have resulted in five commercially available PD-resistant grape varieties. The three new red varieties are Camminare Noir, Paseante Noir, and Errante Noir. For Camminare Noir, the Vitis arizonica variety was crossed with 50% Petite Sirah and 25% Cabernet Sauvignon and has characteristics of both grapes. For Paseante Noir, the Vitis arizonica variety was crossed with 50% Zinfandel, 25% Petite Sirah, and 12.5% Cabernet Sauvignon, and shows distinct characteristics of Zinfandel. For Errante Noir, the Vitis arizonica variety was crossed with 50% Sylvaner (a white grape), and 12.5% each Cabernet Sauvignon, Carignane, and Chardonnay. It reminds tasters of Cabernet Sauvignon.
The two new white varieties are Ambulo Blanc and Caminante Blanc. Although they were both created as initial crosses between the Vitis arizonica variety with 62.5% Cabernet Sauvignon, 12.5% Chardonnay, and 12.5% Carignane, they offer different characteristics. Ambulo Blanc gives wines with Sauvignon Blanc characteristics while Caminante Blanc shows more Chardonnay character.
Table 1 shows the new varieties and the percentage of parental Vitis vinifera varieties used to produce the cross.
Vitis vinifera variety
Let me give you an idea of what to expect from wines made from these new grapes. During the 2022 Texas Wine and Grape Growers Association Grape Camp Conference, wines from two of these varieties were tasted with Jason Moulton, winemaker at Whitehall Lane. Camminare Noir, the cross with 50% Petite Sirah and 25% Cabernet Sauvignon, showed a deep red-purple color, red cherry and black currant fruit, hints of soft herbs and mocha, with a good dose of tannin on a rather elegant finish. Pasaente Noir, the cross with 50% Zinfandel, 25% Petite Sirah, and 12.5% Cabernet Sauvignon, offered a lot of Zinfandel character – dark purple color, plum and raspberry fruit, hints of black olive, licorice, and dried hay with some coffee notes on a round, easy finish.
You may be wondering how these new grapes were named. After looking up common definitions in Italian and Spanish, it becomes relatively easy to understand what prompted Dr. Walker to select these names for his new grape varieties.
Camminare – to walk, to waddle (walk with side-to-side motion)
Paseante – a walker
Errante – to wander, roam, especially by walking
Ambulo – to travel, pass from here to there, especially by walking
Caminante – a wayfarer, a traveler, especially on foot
A recent interview with Dr. Bob Young, CEO and Executive Winemaker at Bending Branch Winery in Comfort, Texas, highlights why these new PD resistant vines have significance here in the Lone Star State. Bending Branch originally planted 16 acres of Vitis vinifera vines on their property south of Comfort, all of which eventually succumbed to Pierce’s Disease. That raised the issue of whether to replant, and if so with what varieties. The goal to farm sustainably, essentially organically without the use of pesticides that might control sharpshooter infestation was a key factor. And the known history that the vineyard was a target for PD infestation from nearby Bruins Creek had to be considered. It was decided to plant PD resistant vines on a limited basis to determine if vineyard survival could be achieved in this location. An acre of a hybrid variety called Crimson Cabernet claimed to be PD tolerant, created from crossing Cabernet Sauvignon and Norton, was planted and the vines appear to be thriving. A second acre of the Walker Cross Camminare Noir was planted this spring (2023) and the vines are just now peeking above the grow tubes (used to prevent rabbits from chewing on the young vines). This Bending Branch experiment is in its infancy, and it will be most interesting to see how things develop over the next few vintages.
At this point you should ask how can I try a wine made from one of these new grape varieties? Now that the propagating and patenting efforts for these Walker Crosses have been completed, they have been released to the marketplace by Novavine, Sunridge, and Wonderful nurseries (perhaps others, too). Unfortunately, the demand is high and the wait-list for receiving vines can be 2-5 years long. Several Texas growers have already ordered Walker Cross vines and some have planted them in various regions of the Lone Star State. Below is a listing of the plantings, as best this author can determine. The expectation is that soon, within the next 3-5 years, some of these new wines will be available in a tasting room near you. ‘More Fun Wine Time in Texas’ is just around the corner.
Here are the Texas wineries I’ve discovered to have these new varieties planted:
Vineyard page: Haak Vineyards & Winery, Santa Fe
Contact: Tiffany (Farrell) Mencacci, winemaker
Winery page: Haak Vineyards & Winery
Varieties: Ambulo Blanc (700 vines), Caminante Blanc (300 vines), and Paseante Noir (300 vines) from Novavine (all on 1103P rootstock) and Errante Noir (600 vines) from Wonderful Nurseries (on its own rootstock)
Vineyard page: Triple N Ranch Winery and Vineyard, Trinidad
Contact: Michelle Anderson
Winery page: Triple N Ranch Winery
First to plant in Texas. Harvesting August 22, 2023 and will make the wine blend Nan’s Leap with it.
Varieties: Camminare Noir, Paseante Noir
Vineyard page: Silver Spur Winery, Hico
Owner: Phil Lopez
Winery page: Silver Spur Winery
Varieties: Camminare Noir (2,000 vines in collaboration with Bending Branch Winery)
- New Pierce’s Disease Resistant Grape Varieties Created from a Vitis arizonica Grape Crossed with Vitis vinifera Grapes, by Prof. Andy Walker, U.C. Davis, 09-Nov-2021 (a presentation made to the Texas Wine and Grape Growers Association Grape Camp meeting in Dripping Springs, TX)
- Move Over Cabernet – Pierce’s Disease Resistant Grapes, A Presentation and Tasting by Carl W. Hudson, Ph.D., C.S.W., Texas Wine Collective Wine Educator and Jason Moulton, Winemaker, Whitehall Lane Winery, Napa, California, 10-Nov-2021 (a presentation made to the Texas Wine and Grape Growers Association Grape Camp meeting in Dripping Springs, TX – Two wines, Camminare Noir and Paseante Noir, from grapes planted at Whitehall Lane in 2016 were tasted by the attendees)
- UC Davis Releases 5 New Wine Grape Varieties: Plants Are Resistant to Deadly Pierce’s Disease, by Amy Quinton, 18-Dec-2019
- New PD-Resistant Wine Grape Varieties Named and Released: Patents Filed for Walker-bred Cultivars Developed at UCD, by T. Rieger, Wine Business Monthly, 2019
- Move Over, Cabernet: Napa Winery Tries Out New, Disease-Resistant Grapes; Rutherford’s Whitehall Lane planted Camminare Noir and Paseante Noir to deal with the threat of Pierce’s disease. But how’s the wine?, by Aaron Romano, Wine Spectator, 3-Nov-2020
- Five Pierce’s Disease-Resistant European Grapevine Varieties, posted by Elina Coneva (Crop Production), 07-Dec-2021
- What’s the Difference Between Crosses, Clones, Mutations & Hybrids?, posted by Vicki Denig (Decanter Magazine), 15-Sep-2021
- Resistant Varieties: The Next Step Toward Sustainability – Will Consumers Agree?, by Loni Lyttle, Wine Business Monthly, p 54-57, April, 2022