Thomcord

Thomcord is a seedless table grape and a hybrid of Thompson Seedless and Concord, developed in the United States by the Agricultural Research Service of the USDA. Its appeal lies in combining the aromatic labrusca character of Concord with the mild, sweet flavour and firm eating quality of Thompson Seedless.

History

Thomcord dates to 1983, when the California grape breeders David W. Ramming and Ronald L. Tarailo, working for the Agricultural Research Service (ARS) of the US Department of Agriculture, crossed Thompson Seedless with Concord. The cross was less a plan to create a new grape than an answer to a technical question: whether plants produced by embryo culture came from fertilised eggs or from maternal tissue. To test this, the researchers emasculated 1,231 Thompson Seedless flowers and obtained 130 ovules through embryo rescue, from which 40 embryos developed and three seedlings were finally planted.

The seedling that became Thomcord was planted in 1984 in plots worked with California State University, Fresno. Ramming and Tarailo selected it in 1986 and trialled it in the San Joaquin Valley under the designation A29-67, before it was introduced as Thomcord. After 17 years of testing, the variety was declared ready for growers and gardeners and was released on 11 September 2003, with trials outside California beginning around 2008.

It won a following at farmers' markets while still under trial and later appeared in the fresh-fruit sections of supermarkets. Even so, it is not expected to become a major commercial variety, since its flavour is less neutral than that of popular grapes such as Thompson Seedless, Crimson Seedless or Flame Seedless. Ramming suggested it could become a specialty product, much like the Muscat grapes, thanks to its distinctive flavour resembling Concord, and that it might compete with Concord and Niabell in eastern US markets.

As a public variety, it is not restricted in propagation or distribution. Virus-free propagation material is offered by the Foundation Plant Services (FPS) at the University of California, Davis, and its genetic material is deposited in the National Plant Germplasm System, although the ARS itself does not distribute plants.

Culture

Thomcord is grown as a fresh-eating table grape and appears mainly in summer, when it ripens between late July and mid-August. Its blue-black skin, of medium thickness and clinging to the flesh, makes it more pleasant to eat whole than Concord, whose skin separates easily, and brings it closer in this respect to Thompson Seedless. Its aromatic taste recalls Concord, the grape so familiar in American juices and jellies, but it is lighter and gentler.

In the vineyard, the variety suits hot, dry climates such as those of California's San Joaquin Valley, and it tolerates powdery mildew, though it is not resistant to it. Fungi can affect its leaves, stems, rachis and berries. Under typical production its yield is comparable to that of Thompson Seedless, and its conical clusters, averaging about 340 grams, do not need the thinning commonly applied to Thompson.

Thomcord's presence on the market today is modest, concentrated in fresh-fruit sections of supermarkets and at farmers' markets. For enthusiasts, its interest lies in tasting a seedless table grape that keeps the aromatic profile of Concord, which is uncommon among fresh grapes.