Trio of New Seedless Grapes on the Way to Consumers

By Marcia Wood
June 18, 1999

FRESNO, Calif., June 18--Three delicious new seedless grapes from scientists here at USDA's Agricultural Research Service may make their way to consumers in the next few years. Melissa, Summer Royal and Summer Muscat are the newest varieties from the 76-year-old grape breeding program at the ARS Horticultural Crops Research Laboratory. Cuttings are now available to growers and breeders.

The Fresno breeding program is best known for developing Flame Seedless, America's most popular red seedless grape. The new varieties have undergone 5 to 18 years of testing in California's San Joaquin Valley.

Melissa, a new white seedless grape, yields large, sweet berries. They ripen about the same time as Thompson Seedless--America's number one seedless grape, said ARS geneticist David W. Ramming. "But unlike Thompson Seedless, Melissa vines don't need to be sprayed with a natural growth regulator to make the plant form big berries. That saves money," he said.

Ramming, who leads the grape breeding research program at Fresno, is a pioneer in "embryo rescue." This is a sophisticated lab procedure he used to produce Melissa and other recent grape varieties. In embryo rescue, scientists remove tiny, developing seeds from promising grapes. In laboratory petri dishes, the seeds are nurtured into tiny rooted plantlets. "These seeds often are mere wisps," Ramming said. "In nature, they probably wouldn't survive."

The Fresno laboratory's new Summer Royal black seedless grape is sweet, large, firm and ideal for snacks and salads. "Summer Royal fills a production gap at the end of August, when there are usually no American-grown black seedless grapes on the market," Ramming said. The California Table Grape Commission helped fund the research.

Makers of candy-coated raisins might want to try the Fresno researchers' new Summer Muscat seedless raisin grape. "This grape has a sweet, strong, muscat flavor somewhat like the traditional 'Muscat of Alexandria' grape,” Ramming said. "But it's easier to candy-coat because it's seedless. Muscat of Alexandria has seeds that have to be removed mechanically. That makes the raisins sticky and hard to process." Muscat-flavored grapes are also used to make sweet dessert wines, he noted.

Summer Muscat is the second dry-on-the-vine or "DOV" grape developed by Ramming's team. Unlike conventional raisin grapes, DOV grapes, which dry naturally on the vine once the cane or branch that they grow on is severed, can be mechanically harvested, thus saving labor costs.

Scientific contact: David W. Ramming, ARS Horticultural Crops Research Laboratory, Fresno, Calif., phone (559) 453-3061, fax (559) 453-3088, dramm@qnis.net.