College of Agricultural, Human, and Natural Resource Sciences

Vineyard, WSU scientists team up to battle new virus threat

Teja Narta, a postdoctoral researcher, and Daniel Hottell, and undergraduate intern at Washington State University, collect soil samples to identify dagger nematodes in a vineyard affected by TRSV (WSU photo).

Something in the soil was destroying Andrew Schultz’ grapevines.

Naidu Rayapati, a virologist with Washington State University’s Viticulture and Enology program, was determined to find out what.

At first, the Grenache vines, planted in a former pear orchard near Wapato, Wash., had been productive and healthy. But over time, a mysterious infection had taken hold.

Mottled, stunted and sickly, the infected vines were producing only tiny, miniature clusters—or no fruit at all. Infected leaves, crisscrossed with white lines, looked as if they had been munched by insects, but Schultz, the vineyard manager, could see no bugs.

“It was unlike anything I’d seen before,” said Schultz. “You should take a look at this,” he told Rayapati, his former professor and an expert on grapevine diseases at WSU’s Irrigated Agriculture Research and Extension Center (IAREC) in Prosser.

After several tests, Rayapati discovered that the grapevines suffered from a damaging syndrome caused by Tobacco Ringspot Virus (TRSV), a pathogen never before seen in Washington state.

“That was a huge surprise,” said Rayapati. “It was a revelation that we have a new problem here.”

Discovered 90 years ago in Virginia, TRSV affects a wide variety of crops, from grapes, apples and cherries to common weeds. It is spread by microscopic worms in the soil called nematodes—specifically, a species called the dagger nematode, Xiphinema americanum. Like the virus, this species of dagger nematodes was also previously unknown in Washington.

Rayapati and Schultz aren’t sure how the virus and its nematode vector arrived here, but Rayapati suspects they may have hitched a ride with pears or other crops years ago.

Damaging virus, hardy vector

TRSV causes vines to become totally unproductive with time.

Large grape clusters from healthy Granache vines compare with very small grape clusters from vines damaged by TRSV (WSU photo).

“In about ten years, you lose everything and the land becomes useless,” Rayapati said. “It’s a very serious problem.”

Since that first discovery, in 2013, the virus remains isolated on that single vineyard block in Wapato. Rayapati, his team of graduate students, and Schultz have been working together on techniques to contain and defeat it.

Grape growers typically get rid of viruses by removing infected plants and replacing them with healthy, virus-free ones.

“Tobacco Ringspot is a totally different beast,” Rayapati said. “Removing and replanting doesn’t stop it.”

That’s because the virus also infects dagger nematodes living in the soil, and those creatures are difficult to kill.

Chemicals can kill the nematodes, but daggers are hardy, and their populations spring back within a season or two.

Rayapati’s research has shown that the dagger nematode species in this vineyard block can spread TRSV from infected to healthy grapevines.

Rayapati and Schultz are testing different combinations of rootstocks and grafts, as well as own-rooted vines, to find grape plants that resist the virus or are unpalatable to nematodes. Schultz is also looking at predatory nematodes that eat the ones spreading the virus.

Best defense is knowledge, soil test

Right now, the best defense against TRSV is knowing when you’re at risk.

“TRSV has a broad host range, and can jump easily from one plant species to another. That’s why we’re trying to alert growers,” said Rayapati. “If you’re planning to switch crops, it’s a good idea to get your soil tested to see if you’re at risk of these nematode vectors.”

Andrew Schultz and Naidu Rayapati partner to keep Schultz’ Wapato vineyards healthy (WSU photo).
Andrew Schultz and Naidu Rayapati partner to keep Schultz’ Wapato vineyards healthy (WSU photo).

“We’re farming 50-year-old pear blocks that pre-date modern clean plant materials, and may someday go to grapes,” said Schultz. “We don’t know what viruses may be in the ground that do not affect pears, but may pop up when we go to grapes.”

WSU IAREC is home to the Clean Plant Center Northwest, which helps growers plant virus-free trees, grapes and hops. Rayapati urges growers to always plant clean vines from a reputable source, reducing their risk of accidentally spreading a virus.

“Once you introduce these diseases, the rest is history,” he said.

Rayapati also urges growers to meet and talk about virus defense.

“On Red Mountain, for example, where grape acreage is expanding, we’re trying to assemble growers of new and existing plantings to discuss the risks,” he said.

Wine is a $4.8 billion industry in Washington. Sixty thousand acres of wine grapes are grown here, with more planted every year.

“It’s important to nip this problem in the bud,” said Rayapati. “Tobacco Ringspot isn’t something that will wipe out the industry, but we need to make sure growers plant virus-free materials and there are no risks in the soil itself.”

For Schultz, researching the virus means saving not just his vines, and the investment they represent, but the Northwest industry—for years to come.

“We could take the vines out and replant with something else, or just fallow the land,” said Schultz. “But, with Naidu, we’re providing answers to other growers who may run into this virus.”

  • Soil testing is available commercially, and Rayapati’s team offers plant testing services. Learn more about WSU IAREC here. Learn about the WSU Viticulture and Enology here.
  • Contact: Naidu Rayapati, Associate Professor, WSU Viticulture and Enology Program, Department of Plant Pathology, (509) 786-9215, naidu.rayapati@wsu.edu.

CAHNRS is more than agriculture. With 24 majors, 19 minors, and 27 graduate level programs, we are one of the largest, most diverse colleges at WSU. CAHNRS Cougs are making a difference in the wellbeing of individuals, families, and communities, improving ecological and economic systems, and advancing agricultural sciences.

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Illustration of a woman holding wine near a music band. Text over the image reads: The Auction of Washington Wines Wine and Music Festival, WSU Tri-Cities Campus, June 10, Saturday 6 pm. Learn More. Support Wine.

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Inspiring Teamwork - Arron Carter pic

Inspiring Teamwork – Arron Carter

It started with a car, a ’69 Corvette Stingray to be exact.

When Arron Carter, the director of the Washington State University Winter Wheat Breeding Program, was in high school his agricultural teacher had a ’69 Corvette Stingray. Every year this teacher would let his favorite senior take the car to senior prom. Carter had never taken an agriculture class before, but he knew he wanted to drive that car.

“Well, if I’m going to be the favorite senior,” Carter said to himself, “I’d better start taking some ag classes.”…

Read More: Inspiring Teamwork – Arron Carter

 










CAHNRS Office of Research

Agricultural Research Center

Mission Statement

The goal of the Washington State University CAHNRS Office of Research is to promote research beneficial to the citizens of Washington. The Office of Research recognizes its unique land-grant research mission to the people of Washington and their increasing global connections. The CAHNRS Office of Research provides leadership in discovering and applying knowledge through high-quality research that contributes to a safe and abundant food, fiber, and energy supply while enhancing the sustainability of agricultural and natural resource systems.

Research Update

Washington State University’s screening continues to find no evidence of glyphosate herbicide resistance in Pacific Northwest wheat varieties

In each of the last three years (2014, 2015 and 2016), the field screening process has involved over 80 varieties, 2,000 advanced breeding lines and more than 35,000 individual plots from WSU cereal breeding and variety evaluation programs. Collectively, varieties included in these trials represent over 95 percent of the wheat acreage planted in Washington.

Featured Research

Want fries with that? Stealth potato virus threatens industry

Newly emerged viruses threaten the U.S. potato industry, including potatoes grown in Washington. Several newly evolved strains of the disease known as potato virus Y, or PVY, can render potatoes unmarketable and reduce crop yield. What’s worse is the new viruses are particularly difficult to detect with the naked eye.

Horned larks undeterred by efforts to protect canola seedlings

Horned larks are turning up in droves near Lind, Wash. and decimating newly planted winter and spring canola fields despite multiple efforts to deter them.

In search of the perfect steak

Imagine taking your first bite of a $40 rib-eye steak—only to chew on beef that’s as tough as shoe leather. Talk about disappointment! “A tough steak is not a pleasant experience,” says Frank Hendrix, a WSU Extension Educator and animal scientist.

Workshops to discuss changing water forecast for Columbia Basin

How changing water availability in the Columbia River Basin could affect people, farms and fish is the focus of a series of free public workshops in June. Scheduled for June 21, 22 and 23 in Richland, Wenatchee and Spokane, the workshops give a first look at the 2016 Columbia River Basin Long-Term Water Supply and Demand Forecast.

After landslide, communities rewarded for resilience

Two years after the deadly landslide that devastated the Oso, Wash., area, the towns of Darrington and Arlington were announced April 27 as finalists in the America’s Best Communities (ABC) competition.

$11M funds food safety tech transfer to markets

WSU aims to meet growing demand for safe, high quality, additive-free packaged foods thanks to two recent investments in innovative food processing technology based on microwave energy.




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Contact Dean’s Office:
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