Dried plums so sweet they "taste like candy" will soon make their way to grocery store shelves, according to UC Cooperative Extension farm advisor Carolyn DeBuse. At least for the time being, however, it may be difficult for consumers to identify this particularly sugary fruit since they won't be labeled differently.
The new dried plums are a patented variety developed by UC scientists at the behest of the state's dried plum industry. Over a period of 25 years, scientists painstakingly used traditional breeding techniques to capture just the right genetic traits, eventually singling out and naming the Sutter dried plum.
"Sutter is really high sugar, then has this wonderful filling out of fruit flavor," DeBuse said.
Four years after selecting Sutter, the scientists found another excellent dried plum, now the patented Muir Beauty.
"Muir Beauty is even more distinctive," DeBuse said. "It has a burst of fruit flavor and extra meaty interior flesh. One day, you may find Muir Beauty dried plums being marketed, like fine wines, as a varietal."
The different taste and texture of the newly crafted dried plum varieties will provide a subtle, but pleasant change for consumers, who are accustomed to the dominant French Improved variety.
"French Improved dried plums have a sweet, but grassy flavor and are probably the taste most recognized as prunes," DeBuse said. "That's different than the more fruity tones — like peach and apricot — found in the Sutter and Muir Beauty."
The dried plum industry is welcoming the new varieties with open arms -- not so much for the taste sensation, but to extend the length of crop harvest. Since mechanical harvesting became the standard in dried plum production, farmers have relied almost exclusively on French Improved, which bears fruit that ripens all at the same time. The useful trait carried with it the need to harvest thousands of tons of dried plums around the state and quickly get them into dehydrators, all within a span of three or four weeks in late summer.
Years ago the dried plum industry realized that developing new cultivars with different ripening times would spread harvest and drying over a longer, more manageable, period. They began funding the decades-long UC breeding effort, which brought to fruition the Sutter and Muir Beauty varieties.
California's world dominance in dried plum production is indisputable. A French nurseryman introduced the fruit to the state in 1856. According to the California Dried Plum Board, California farmers are expected to harvest 120,000 tons of fresh prune plums this year — 99 percent of the United States' total and 70 percent of world's dried plum production. Dried plum farms are found mainly in the Sacramento and San Joaquin valleys.
For many years breeding crosses were made by Jim Doyle, a staff research associate at the UC Kearney Research and Extension Center near Parlier, working under the direction of UC Davis pomologist Ted DeJong. When Doyle retired in 2002, the breeding program headquarters moved to Davis and under DeBuse's management. DeBuse was named the pomology farm advisor for Yolo and Solano counties this year, and day-to-day management of the dried plum program shifted to Sarah Bradley, with guidance from DeBuse and DeJong. Trees in the program are cultivated and tested at UC Davis, at the Kearney Research and Extension Center, at Wolfskill Experimental Orchard in Winters, and on cooperating growers' farms.
The Sutter variety, patented and released in 2000, was the result of a cross made in 1987 between two European plum cultivars. The Sutter plum is large, dark purple with a waxy bloom and dries into a very high quality fruit. The key to its selection was a ripening date 7 to 10 days earlier than Improved French.
The Muir Beauty, a cross made between European plum cultivars of Improved French and Tulare Giant in 1992, dries into a visually appealing, shiny, somewhat less wrinkled fruit. It matures 10 to 15 days before Improved French. Muir Beauty was patented and released in 2004.
"A farmer could plant sections of all three varieties and really split up the harvest dates that way," DeBuse said. "I think there is a place in the industry for all of these three dried plums."
Sutter can already be found on California dried plum farms. Selected four years later than Sutter, Muir Beauty is currently being field tested in farmers' orchards.
The success of the UC dried plum breeding program has only encouraged the dried plum industry to request varieties with other favorable characteristics.
"We're looking for a dried plum with unique flavors for the gourmet market," DeBuse said. "We're selecting for dried plums with more dried cherry flavor or more apricot flavor. We hope there will be a niche market that would embrace something completely different."
Also on the industry's wish list are new dried plum varieties with different bloom times.
"If the weather is warmer than 80 degrees during bloom, the fruit doesn't set. A springtime heat wave that coincides with bloom can wipe out the entire crop," DeBuse said.
For example, the 2004 crop was severely damaged by a mid-March hot spell. That year total crop value was $72 million, compared to nearly $130 million the year before, according to the National Agricultural Statistics Service.
"The last five springs we've had spikes in heat during bloom," DeBuse said. "Last spring we had a three-day spike and certain areas lost a lot of fruit, but the overall state crop will be good this year. The dried plum industry is desperate to solve this problem."
The dried plum breeding program is now carefully tracking bloom dates of the cultivars under study to help the industry spread out bloom time over a longer period, ensuring a sustainable crop year to year.
The industry is also interested in dried plum varieties with better disease control, better pest resistance and better tree structure, ensuring the continued necessity of the proven UC dried plum breeding program long into the future.
A two-minute video of Yolo County Fair visitors commenting on the two new dried plum varieties is online at http://ucanr.org/driedplums.