Good Fruit Grower / July 2007 / Organic juice grapes

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Organic juice grapes

Juice grapes have few pest pressures, making them good candidates for organic practices.

Washington State Concord and Niagara grape juice growers are well positioned to take advantage of a growing market for organic juice concentrate, although organic juice grapes are still a small percentage of total production.

Grape juice processors report a "good, growing market" for organic grape concentrate, according to Jack Schroeder of Johnson Concentrates, Inc., in Sunnyside, Washington. Sales of organic grape juice concentrate have increased 20 to 25 percent each year in recent years, he said, adding that organic grape concentrates are one of the most popular of the fruit concentrates because they are readily available.

"Concords are only used for juicing, so there's no competition for product to go to the fresh market like there is with apples," he said.

Schroeder also sees growth opportunities because organic Concord juice concentrates are still reasonably priced. The difference between conventional and organic cranberry concentrate is about 75 percent more for organic, compared to Concord price differences of $10 per gallon for standard and $13 per gallon for organic concentrate.

"Washington State is the only place where you can grow organic Concords," Schroeder added, explaining that disease pressures are too great for East Coast Concord grape growers to be successful with organic production. "There's still a goodly amount that we can grow."

He estimated that about 5 percent of the state's acreage is produced under organic practices. Growers receive about a 30 percent premium for organic Concords compared to conventional juice grapes.

Grower experience

Olsen Brothers Farms, owned by Larry and Richard Olsen, are among ten or so growers in the state producing organic juice grapes. They began with 40 acres of organic Concords about eight years ago. Today, they have 80 acres of organic Concord grapes.

"We got into organic purely for market opportunities," said Keith Oliver, manager at the Prosser farm that includes apples, cherries, hops, wine and juice grapes, and newly planted blueberries. Olsen Brothers had organic apples years ago but got out of organic apples because of difficulty controlling pests.

Concord grapes could be the poster crop for organic farming in Washington because there are not really any pest issues, said Oliver, adding that they haven't had any cutworm or mite problems and mildew is not a problem in juice grapes.

Weed control

"Weed control and fertility are the two big challenges," he said. "That's where all the money is spent."

They have tried various weed controls through the years, including using steam and propane to kill the weeds. They even spent time wrapping plastic irrigation pipes with aluminum foil to protect them from the heat. But they've gone back to using a cultivator under the vine row, making an average of six passes annually.

"You've got to get to the weeds when they are small," said Oliver. "If you get behind, you have a real mess."

Leif Olsen, son of Larry, said weed control—without the benefit of herbicides—is a continual battle. "It seems like that's all you do is work on the weeds."

Weed mats have provided effective weed control in some cherry orchards in Oregon, but the grower returns in Concord grapes wouldn't justify the expense, he added.

Nutrition

Oliver explained that they rely solely on leguminous cover crops for vine nutrition, growing their nitrogen in place. The transportation and spreading costs make compost too expensive.

Olsen and Oliver have worked with Washington State University researchers in the last few years, providing plots for cover crop research. They have observed trials comparing different clovers, vetch, and grass mixes in the vine rows.

Based on the trial results, they now use hairy vetch as the cover crop to fix nitrogen in the soil. Oliver said hairy vetch is a strong grower that produces lots of biomass to incorporate in the soil. They seed it in August, mowing it in late spring and in the summer for incorporation into the ground. The soil must be warm and moist for microorganisms to be working. In eastern Washington, soil microbes are busiest in the summer months, but that's not when nitrogen release is wanted in the vineyard.

Overhead sprinklers used to irrigate the vines help establish the cover crops, he said, noting that it still takes a lot of effort to grow cover crops.

"We don't want a flush of nitrogen in the summer, but you get it when you get it," Oliver said, referring to the mineralization of nutrients. "Over time, it works, and the plant gets what it needs when it needs it."

Vine vigor and grape yields indicate if the vines are receiving enough nutrition. Thus far, the organic vineyards haven't shown any signs of weakening vigor or yields. "If the yields were going down, we'd see it, but there hasn't been a trend yet," he said.

Foliar leaf feeds, including fish oil products, are also used to provide other micronutrients, although Oliver noted that leaves are an inefficient way for vines to take up nutrients.

Low inputs

The goal at Olsen Brothers is to grow both organic and conventional juice grapes with minimal inputs. They have changed their pruning style in both organic and traditional grape blocks, minimally pruning canopy and removing only canes that hang down.

"We are trying to do all of this with low inputs," Oliver said. "It's a lot easier to grow conventional juice grapes. We're not getting rich on organics."

A few years ago, juice processors were not very interested in purchasing organic Concords, he noted. However, last year, they wanted all they could get.

Moreover, there has been little information to help guide organic juice grape growers in the area of nutrition and fertility. Oliver said that mainstream agricultural production scientists are learning more about what goes on underneath the soil, but there is still much to learn. He believes that WSU's new Biologically Intensive Agriculture and Organic Farming department will help bring more science to organic farming, assisting many conventional growers with new practices and concepts used in organic farming.