Recent Washington State grower experiences of finding disease in a vineyard planted with certified stock have highlighted the weaknesses of state plant health certification programs and the need for program improvement.
“We thought we had something clean, and we were going down the road thinking we had some nice, clean stock,” said Rick Hamman, viticulturist for Hogue Ranches in Prosser. But when the certified budwood from California turned out to be infected with at least two diseases, it became a learning process for the company. He believes that as an industry, Washington needs to know more about out-of-state certification programs—how often registered material is tested, and what viruses are targeted. “We need to understand what we’re getting when we do get wood from California.”
When clean isn’t clean
Hamman shared a recent experience of bringing in 50,000 cuttings of certified Chardonnay, clone 37 budwood from a California nursery for propagation. As early as the second year of the block’s production, the vines started looking “funny,” he said. The previous year, vine growth had looked off, but he thought it was a nutritional deficiency. Foliar samples showed low levels of magnesium, so magnesium was shanked in for three seasons.
Before the 14-acre block began to show disease symptoms, Hamman said another small block was planted from the same budwood. That block, in a different site than the first, also started to show “funny-looking” leaves in the second leaf.
During the 2010 season, the 14 acres of Chardonnay vines struggled to achieve sugar, finally reaching 20.2° Brix on October 15. Hamman said the grapes were harvested, but the fruit never reached 21° Brix.
Lab analysis confirmed what Hamman feared. The Chardonnay vines were infected with Rupestris stem pitting and grapevine leafroll viruses. He thinks the vines might have had esca or young vine decline as well, though those viruses were not tested for, because leaf symptoms were very similar to those described by Dr. Doug Gubler.
Both blocks were removed at the end of 2010. “So, we lost 14 acres and about seven years, counting time needed to get back into production,” he said. Additionally, he had to dump 50,000 plants that were to be planted in 2011.
Dick Boushey, Grandview grape grower, suspects that he had esca or black measles in a small block of Roussanne grapes sourced from a California nursery that was planted seven years ago. Initially, after a petiole analysis, he thought the vines had a potassium deficiency, yet potassium applications didn’t correct the problem. Symptoms were yellowing of the leaves and a tiger-striped pattern. In 2010, symptoms went full-blown, he said, adding that fruit had purple spots that dried, exposing the seeds. Of the fruit that could be harvested, Boushey said the sugars were low.
Boushey was concerned that disease could spread to adjacent vines, so he recently removed them. (Vines were being tested in a laboratory, but results of the tests were unknown at the time of the seminar.)
“This was supposedly certified wood, and I had it tested for all the known viruses when it was planted. All the tests were negative,” he said. “I don’t know that it was esca, but it fit every symptom that Dr. Gubler talked about.”
Finding strange symptoms in your vineyard is a scary experience, Boushey said. “But it does lead to ‘we probably can’t do enough as far as scrutinizing the wood we plant and where it comes from.’ We think as an industry we’ve done enough, but we really haven’t—this year really brought out everything that was out there.”
He noted that while 2010 was a unique weather year, cool years will come again. “I’ve experienced a season like 2010 four or five times in my career. It will happen again. We’re on the edge of growing vinifera, so we’ve really got to be more diligent than other areas.”
Mike Sauer of Red Willow Vineyards in Wapato has had similar experiences as Boushey and Hamman. Even though he has planted certified material, he’s had Washington State University’s Dr. Naidu Rayapati out several times to look at different symptoms. “Of Petite Sirah, Dolcetto, and some of these newer varieties that I’ve planted, I bet half have showed different symptoms and I’ve ended up pulling them.”
Sauer shared that in his 40 years of grape growing, production practices and pest and disease concerns have changed. Twenty-five years ago, phylloxera was the big nursery concern, and vines were three or four years old before they were cropped. Demand for new varieties and clones has often resulted in shortages of nursery stock for certain material—growers and wineries are in a hurry to get material planted to hit peak prices for “hot” varieties.
What does certified mean?
Kevin Judkins of Inland Desert Nursery, Benton City, produces Washington State-certified grapevines. His father started the nursery business in the 1960s. With the revamping and updating of the grape foundation block housed at WSU’s Prosser research station and the newly created Northwest Grape Foundation Service, Judkins said there’s been vast improvement in what “certified” means. “Certified stock didn’t mean anything years ago.”
Though it’s been a slow process, the new H-20 foundation block that was planted in 2004 has given nurseries more confidence that the plant material they use for new registered blocks is clean. Most of the old registered nursery blocks in the state have been abandoned and new blocks have been planted from the H-20 vines, he said, noting that there was a lag period when new material from the H-20 block was converted to new registered blocks.
“We have opportunity to learn from California’s mistakes,” Judkins said. “They had clean material at one time, but being planted in registered blocks for numerous years—decades—it was lost somewhere along the way. Things change, which is why testing of registered blocks needs to be done more than once every ten years.”
The panel of growers and nursery representative was part of a grape disease seminar held last month at WSU’s Tri-Cities campus.