Last month’s discovery in Walla Walla Valley of grape phylloxera, a microscopic, aphid-like louse that destroyed much of the world’s wine grape vines in the late 19th century, reverberated quickly across the Washington State wine industry.
First up. What does the presence of phylloxera in Washington State mean for the wine-consuming public? Not much.
“This truly does not have an impact to the consumer, as it does not affect wine quality,” says Steve Warner, president of Washington State Wine.
Rather, phylloxera affects grapevine productivity. As they feed, the insects damage grapevine roots. Over time, this reduces vine vigor, making it uneconomical to continue growing fruit and forcing replanting. Phylloxera can also inhabit leaves, but this form of the insect has not yet been found in Washington.
Warner notes that Washington is far from alone in facing this issue.
“The vast majority of the world’s wine regions have successfully managed their vineyards despite the presence of phylloxera, and we will too,” he says.
Indeed, wine regions throughout Europe, California, Oregon and elsewhere have all combated the insect at some point.
“We suspect that [phylloxera] had been in that one spot for quite some time, but it hadn’t moved, which is very good news.” —Chris Figgins, president/director of winemaking, Figgins Family Wine Estates
Due to phylloxera’s effect on vine vigor, the vast majority of the world’s wine grapes are now grown on phylloxera-resistant rootstock. This means combining European grape vine varieties we are all familiar with (the species Vitis vinifera) with rootstock from various North American vine species that have natural resistance to the pest.
Washington State, however, has long prided itself as one of the world’s few wine regions nearly 100% planted on vinifera rootstock. It’s so much a part of the culture that one of the state’s founding wineries, Chateau Ste. Michelle, lists “100% vinifera rootstock” on some of its wine labels. Being “own-rooted” has become engrained in Washington’s identity.
How did phylloxera find its way to Washington?
While finding phylloxera in Walla Walla Valley came as a shock to some, the insect’s presence is by no means new to the state. Phylloxera has been in Washington since at least 1910, when it was first found in the city of Kennewick.
The Washington State Department of Agriculture has analyzed 100 sites annually in recent years to track phylloxera. Typically, the number of cases identified has been extremely small.
Why has phylloxera’s growth been limited in Washington to date, while the pest has proliferated everywhere else?
“Phylloxera itself, under Washington soils and environmental conditions, it survives, but it doesn’t thrive,” says Michelle Moyer, associate professor in horticulture and viticulture extension specialist at Washington State University.
Most of eastern Washington, where the vast majority of the state’s wine grape vines are planted, have soils that are quite sandy. That limits or can even eliminate phylloxera’s ability to reproduce. Due to the high sand content, the belief was that phylloxera couldn’t build numbers that would cause problems.
“That’s true for most of Washington,” says Katie Buckley, entomologist at Washington State Department of Agriculture. “Unfortunately, that’s not true for all of Washington.”
Why are people finding phylloxera now?
“The biggest reason people are finding it is that they are actually looking for it,” says Moyer.
The Walla Walla Valley and beyond
Chris Figgins, president/director of winemaking at Figgins Family Wine Estates, which includes Walla Walla Valley’s first commercial winery, Leonetti Cellar, explains what happened in the valley this way.
“There’s this one block [in part of the valley] that for years had a weak spot in it,” he says. “We just couldn’t seem to get the vigor in it. Our entomologist started doing the math and started digging, and, sure as hell, she found phylloxera.”
Figgins says it’s unlikely the insect’s presence there is new.
“We suspect that it had been in that one spot for quite some time, but it hadn’t moved, which is very good news,” he says.
After quickly meeting with partners that own vineyards near the identified area, there was a subsequent gathering of the larger Walla Walla industry to discuss the issue. More investigation led to more findings of the pest.
“There are going to be growers here that are going to have to slowly replace their vineyards with grafted rootstock. But I suspect there will be others that will never have a problem.” —Katie Buckley, entomologist, Washington State Department of Agriculture
While not an issue that affects consumers, these new detections of phylloxera do have potential significance for the state’s 350+ grape growers. While Walla Walla Valley has received the brunt of attention by speaking up publicly about its phylloxera discovery, this is an issue likely for other growing regions in the state as well.
“I can assure you, it’s not isolated to Walla Walla,” says one grower, on the condition of anonymity. “It’s in other areas. You can see it if you know what you’re looking for.”
Still, the current thinking is that phylloxera’s presence in the state is limited.
“We estimate that the number of affected vineyards in the state of Washington is still extremely low,” says Warner.
Trying to keep it that way will involve numerous state and local agencies.
“We will work with growers and researchers to determine the best long-term management strategy,” says Warner.
At present, the Washington Winegrowers Association has re-emphasized practices to limit the spread of phylloxera and other pests.
“We’ve been reminding everyone about best practices, sanitation and particularly restricting soil movement,” says Vicky Scharlau, the group’s executive director. It will seek to fund a comprehensive survey of the state to look for the insect.
The phylloxera upside
The good news for Washington grape growers and wine lovers? The problem that phylloxera presents has already been solved throughout the world. Long-term, affected areas will be replanted to phylloxera-resistant rootstock, just like everywhere else.
“You play that game of the time until a vineyard is no longer economically profitable, then you replant,” says Moyer. “If an area is not affected, you don’t have to switch to rootstock.”
In fact, a small number of growers have already planted on rootstock in anticipation that this day might come.
It’s likely that vineyard practices will shift as well. In recent years, some growers have limited the use of herbicides in favor of mechanical weeding. That might change.
“There’s no better way to spread [phylloxera] than dragging a weed badger through a vineyard,” Figgins says. “So we’ll need to rethink that.” Equipment will have to be sterilized before being shared across sites.
A number of growers that intended to plant vineyards next year have said that they’ll wait another year to plant on rootstock. However, given the expected slow growth of phylloxera in the state, growers anticipate there’s plenty of time to plan and perhaps eventually replant.
“To me, this is a 20- to 40-year transition that’s going to happen,” says Figgins. “This is a long-term situation. It’s not a qualitative impact. It’s manageable.”
Buckley agrees. “There are going to be growers here that are going to have to slowly replace their vineyards with grafted rootstock,” she says. “But I suspect there will be others that will never have a problem.”
“We have some 40-year-old vines. I’d like to see them at the end of my career be 80, but I don’t know if that’s going to happen now.” —Chris Figgins
Replanting could even have a silver lining. Rootstock is used all over the world to manage other pests, not just phylloxera. One such pest, nematodes, affects some Washington vineyards. Different rootstocks are also used to control issues like vigor and manage poor soil conditions.
“Maybe this is the chance to get people to reconsider the value of rootstocks in Washington’s production and the added tool it can give a viticulturalist,” says Moyer.
Still, it’s hard not to feel some sense of loss.
“I won’t pretend that I didn’t wish we were own-rooted forever,” says Figgins. “We have some 40-year-old vines. I’d like to see them at the end of my career be 80, but I don’t know if that’s going to happen now.
“We’re going to do our darnedest, especially with some of our old blocks, to keep them clean as long as possible. We’ll gradually have to replant things. If any block gets below an economic threshold, then it will have to happen.”
Sean P. Sullivan is a contributing editor at Wine Enthusiast and is also an educational consultant for Washington State Wine.