Organic Table Grape Variety Trials

In 2003, the CSU Specialty Crops Program had a small demonstration plot of table grapes at the W.D. Holley Plant Environmental Research Center including the following varieties: Fredonia, Concord, Himrod, and Reliance. In 2004, a variety trial was established on certified organic land at the Horticulture Research Center northeast of Fort Collins, Colorado. Ten plants each of the varieties listed in the table below were planted 8′ apart on June 16, 2004. We rented a tractor-mounted post hole digger to excavate the holes more efficiently. Half of the plants were treated with an endomycorrhizal root dip and half were left untreated. All vines planted were one year old vines (bare root stock), except for the variety Vanessa whose vines were 2-years old. We spread composted dairy manure on top of the soil in mid-summer 2004. The varieties Swenson White, St. Theresa, and Flambeau were potted plants and were obtained and planted on August 4, 2004. In 2005, 10 potted plants of the the variety Valiant were added to the variety trial and planted on May 16, 2005.

Varieties were chosen for productivity and cold hardiness, many having been bred in Wisconsin and Minnesota. Wind dessication can be a problem here, almost as much so as the cold temperatures, so it can be difficult for plants to survive the harsh conditions. We had 24% mortality of the grapes after planting and before the winter of 2004-05. In the spring of 2005, there was an additional 28% winter mortality rate. Interestingly, the treatment with the endomycorrhizal root dip did not appear to play a role in decreasing transplant shock or in aiding winter survival. By the spring of 2005, the grape plants with the endomycorrhizal root dip had 34% mortality and those without the treatment only had 22% mortality. Insufficient watering may have played a role in some of the mortality. During the summer of 2006, we watered more frequently, applying approximately 1″ of water per week.

The plants will be trellised in the spring of 2006 and we hope to have our first year of grape production in the summer. See below for photos (all photos are courtesy of Cornell University) and descriptions of the planted grape varieties.

Photos (courtesy of Cornell Univ.)
Variety
Description
Einset Seedless
Red seedless grape, strawberry-like flavor, medium sized clusters with good storage potential.
Photo Not Available
Flambeau
An Elmer Swenson variety, pink seedless grape.
Mars
From the University of Arkansas, a blue seedless grape, has proven to be hardy in New York.
Reliance
From the University of Arkansas (1982), red medium-sized seedless berries, among the best varieties for cold hardiness.
Photo Not Available
St. Theresa Seedless
An Elmer Swenson variety.
Sheridan
Black Concord-type berries, seeded, vigorous, hardy, easy to grow, late producer.
Swenson Red
University of Minnesota and Elmer Swenson variety, large, seeded, red berries, hardiness in Minnesota was marginal but did well in New York.
Photo Not Available
Swenson White
An Elmer Swenson variety, hardy white grape, ripens late in the season.
Valiant
a deep blue-purple fruit, good for eating, jelly, and juice, very hardy grape, self-pollinating (photo courtesy of cornhillnursery.com)
Vanessa
Red dessert grape, seedless, hardy variety, medium-sized firm berry, recommended as the best among red seedless types .

Other Sources of Information About Grapes

Photos are courtesy of Cornell University – see the link to their report on Table Grape Varieties for Cool Climates. See also the websites at the University of Arkansas and the University of Minnesota about their grape breeding programs.

 

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