Species: V. vinifera
Country of origin: Turkey
Berry color: White
Use(s): Wine, table, raisin, concentrate
Thompson Seedless, regarded primarily as raisin cultivar, is the most widely planted white table grape grown in California and its origin and history are well documented. The cultivar was among a group of cuttings bought from a nursery in New York in 1878 and planted by William Thompson of Marysville, California. Thompson propagated the cuttings and gave a number of them to his neighbor, John Onstott of Yuba City. It was Onstott who realized the commercial potential of the cultivar and achieved great success with it. In 1892 he shipped over two million cuttings and rootings of Thompson Seedless to growers throughout the state; however, most went to the San Joaquin Valley. It is interesting to note that although the cultivar was named after Thompson, the first person to bring it into California, it was later discovered by horticulturalists that it was the same as Sultanina grown in Asia Minor. The cultivar is known by several other names around the world including Oval Kishmish (Eastern Mediterranean), Ak-Kishmish (Russia), Sultana (S. Africa and Australia) and Chekirdeksiz (Turkey).Thompson Seedless produces large, cylindrical-shaped, heavily shouldered clusters that ripen in early to mid-August in the San Joaquin Valley. The berries are seedless, medium-sized, ellipsoidal in shape and greenish white to golden in color. Its rise in popularity in California was largely due to its seedless character, thin skin and crisp texture. There are over 10,000 hectares of Thompson Seedless grown for table grapes in California.
'Thompson Seedless' is by far the most widely planted grape variety in California. It is also the most versatile of grape varieties. While the largest proportion of its acreage is devoted to raisin production (about 70 percent), a substantial proportion is used for fresh table grapes (about 14.5 percent), crushing for wine, grape juice concentrate, and distillation products (about 14 percent), and canning (about 1.5 percent).
The versatility of 'Thompson Seedless' also extends to its use as raisins. While it is most widely known for production of natural sun-dried raisins (about 93 percent of the 'Thompson Seedless' raisin crop), about 7 percent of its raisin crop goes to commericial dehydrators to make golden seedless (about 4.5 percent) and dipped seedless (about 2.5 percent) products.
Foundation Plant Services at UC Davis is the source of Foundation grapevine material for the nursery industry, and the staff can provide information about possible sources for obtaining this stock.
The National Grape Registry (NGR) contains information about varieties of wine, juice, and table grapes, raisins, and grape rootstocks available in the United States. Growers, nurseries, winemakers and researchers can find background information and source contacts for those grape varieties in this single convenient location.