by Tamara Scully
Sometimes it seems that wine grapes get all the glory. But grapes are meant for eating fresh, too. Table grapes available in supermarkets are generally of the Thompson seedless or Flame seedless variety, both of which are Vitis vinifera, European grape cultivars. European grapes include the well-known varietals common to French wines. And most of the production of those grapes comes from California.
More than three-quarters of all grapes produced for any purpose in the United States come from California, with Oregon and Washington also among the states with significant production. In the northern part of the eastern United States, New York, Ohio, Michigan and Pennsylvania are significant grape-producing states, although they can’t compare to California.
Growers in many wine-production regions do plant European grape vines. But much effort has gone into developing wine grape varieties more suited to regional growing conditions. These breeding programs focus on the wide variety of native grapes — Vitis labrusca, Vitis riparia, Vitis rotundifolia, and others — and have resulted in varietals such as Frontenac, Elvira, Catawba, Niagara, Concord and more.
Many of these native grapes are great for fresh eating, too. More breeders are embarking on the journey of developing new grape cultivars with characteristics needed for fresh eating. Table grape production can offer farmers the opportunity to direct-market to consumers and to diversify their crop production and plant a vineyard, without the need for a winery.
Fresh eating grape concerns
Cornell Cooperative Extension’s Eastern New York Commercial Horticulture program sponsored the “Growing Table Grape For Profit” three-part webinar series earlier this year. The series included information on site selection, fertility needs, general cultivation and trellising, variety trials, economics and markets.
Farmer Nicolas Bozzo, from Nostrano Vineyards, discussed the difference between growing and harvesting wine grapes and table grapes.
“These are table grapes. You want to have good color, you want them to have good flavor,” Bozzo said, emphasizing the importance of each individual grape cluster. “You have to have a visual presence when you’re growing table grapes.”
Variety selection depends on the site’s microclimate, as well as the grape’s characteristics. Interlaken, Gratitude and Hope are some green varieties he grows. Einset, Somerset and Canadice are some of the red grapes.
“A lot of them have different flavors, a lot of them have different characteristics — the skin, the texture,” he said of table grape cultivars.
Vine health, as well as grape quality, are the keys when pruning. Increasing fruit set and developing the color and sugars needed for fresh eating is imperative. Harvesting needs to be accomplished using smaller trays than is typical with wine grapes to prevent crushing. Table grapes are picked repeatedly, not all at once as with wine grapes, as each cluster ripens over the period of a few days. The grapes need to be put immediately into cold storage, where they can remain fresh for several months.
Direct marketing via farmer markets or farm stands is primarily in quarts, so field picking right into the container is customary, Bozzo said. For sale to other retail outlets, table grapes are hand washed, weighed and packed into labeled two pound clamshells, six to the flat, which is “one of our largest markets.”
Bozzo recommends that grapes be planted away from trees or wooded areas, which helps to protect from disease and pest pressures, and on a site with good drainage. Planting in north/south oriented rows is the preferred option for optimal sun exposure.
A cover crop, tilled deep before planting vines, is a best practice. Installing the trellis system immediately after planting, before the vines need it, is too. Rows should be at least eight feet apart depending on equipment, with vines planted six feet apart, he said.
Fertility, pests and disease
“It’s really all the same whether you’re growing grapes for juice, or table grapes or wine grapes,” Hans Walter-Peterson, of the Finger Lakes Grape Program, said. “The more we can do to let the natural cycle provide the nutrients for the vines, the better off we are.”
Fertilizer should “fill in gaps” in soil fertility. Applying needed nutrients so that they are available at the time the plant requires them is key. Before planting the vineyard, soil pH levels should be amended. Soil water content in important in nutrient availability, too. Soil and tissue sampling allows growers to accurately assess fertility in the vineyard.
Birds are a primary pest of grapes, eating ripened fruit. Visual scare devices, or calls of predatory birds, can be used as a deterrent but need to be repositioned regularly to remain effective, Anna Wallis, Cornell Cooperative Extension Specialist, said. Physical barriers, such as netting, are recommended.
“Birds can be a huge pest for vineyards” eating the entire crop overnight, Wallis said. “As soon as the berries turn color, that’s veraison. That indicates to birds and other pests that the fruit is ripe and ready to eat.”
Deer will eat the tender shoots off the vine. Mice and voles can girdle the vines. Controlling weeds is the best way to eliminate rodents, while vineyards with deer pressures require appropriate fencing.
Insect pests include Japanese beetles, which defoliate plants although vigorous vines can recover. The grape berry moth will feed on clusters during bloom, and its larvae will enter the fruits. As larva mature and move out of the berries, effective insecticide applications can occur.
“Diseases are by far the most important pest that you are going to be managing in a vineyard,” Wallis said. “We have unique challenges in that most of these disease pests are active and can infect plants, even before we can detect them.”
Preventative and protective controls are key to combating disease. Common disease pressures in vineyards include phomopsis, which impacts green tissues and causes misshapen leaves and berries that shrivel and fall off. Pruning out damaged wood is the effective control.
Black rot and downy mildew are two main fungal concerns in humid climates. Removing diseased plant materials, including berries, reduced disease pressures as the fungus can overwinter in plant materials.
Viral disease, including red blotch and leaf roll disease of grapes, are transmitted by propagation of plants and do not always have visible symptoms. Purchasing clean plant materials is a critical component of vineyard disease control. Without symptoms, vines appear healthy, but are actually serving to allow the spread of the virus to other vines.
Viruses “can cause a lot of harm to vineyards, and can also be latent,” Wallis said. “All of these are vectored by humans.”
Canopy management, including shoot thinning, maximizes air control and reduces conducive disease environments. Chemicals must be applied at the correct time and materials must be targeting the specific disease of concern. Resistance management, via rotating FRAC codes, is also necessary.
“It all will mean nothing if you don’t get good coverage,” Wallis said. Equipment calibration and proper equipment use is important in effective pest and disease management.
Growers of grapes for fresh eating not only need healthy vines: they need great-looking fruit, loaded with flavor, and picked at the peak of ripeness. Locally grown table grapes fit the needs of the Buy Local movement. The development of cultivars, suited to different microclimates, offers ample opportunity for diversification and expansion in the table grape market.
The recorded webinar can be viewed at www.youtube.com/watch?v=mjtK1ryfntw.