In California, the new Sunpreme raisin grape, bred and patented by now-retired Agricultural Research Service horticulturalist David Ramming, dries on the vine without cane cutting and could save millions of dollars in production costs. With other raisin grapes, crews cut the grape-producing branches about two weeks before harvest to cause wilting; and then the raisin grapes can be shaken into a tray at harvest. Cane cutting costs about $130 per acre, which is roughly 36 percent of total harvest costs.
The results confirmed that Sunpreme vines only need to be spur pruned, requiring less skill than cane pruning. Grapes from spur-pruned vines were comparable in size, quality and number to grapes from cane-pruned vines.
Sunpreme grows well in the San Joaquin Valley, where roughly 200,000 acres of raisin grapes are produced each year. Five nurseries have licenses for the new grape and some are already taking orders from grape producers.