Breeders aim for a perfect cherry

Left: Sentennial is a new late-season cherry from British Columbia. Right: Sovereign was named in honor of Queen Elizabeth’s 80th birthday.

The perfect cherry variety, from the producer’s point of view, would be well adapted to the location, cheap to produce, high yielding, and self-fertile. The fruit would be large, firm, sweet, and resistant to cracking, pitting, bruising, and diseases. It should ripen either early or late, but not midseason.

For 70 years, fruit breeders in British Columbia, Canada, have been trying to develop the ideal cherry for the province’s growers, and the cherry breeding program has released some successful varieties, starting with Van in 1944. More recent releases from the Summerland breeding program include Santina, Skeena, Staccato, and Sweetheart. However, many of the other varieties released have not become commercial successes, cherry breeder Dr. Frank Kappel reported during the Washington State Horticultural Association’s annual meeting. Some faults don’t become evident until the varieties have been extensively planted and tested.

“Even if a variety is released, you have to be careful in the amount of trees you plant, and get involved in the testing as early as possible,” he told growers. “None of the varieties are perfect. They’re all going to have their little glitches, and we need to find them out as quickly as possible.”

Screening

Kappel can now screen for certain traits during the selection process. For example, selections are screened for their susceptibility to brown rot and Botrytis. Some selections are less susceptible to brown rot than others, though none are immune, he said. For example, if 90 percent of the fruit of a susceptible variety are infected, the less susceptible variety might have 60 percent fruit infection. “It’s not huge, but there’s some level of resistance,” he said.

He’s also beginning to screen for mildew resistance, and is starting to look at stem-pull force to assess how easily a cherry would detach from the stem for mechanical harvesting.

Asked if a firm variety tends to be more susceptible to cracking than a soft variety, Kappel said his research has shown no relationship between the firmness of a variety and the amount of cracking. However, within a variety, a firm cherry might crack more easily than a soft cherry.

New releases

The latest releases from his program are Sovereign (13S-21-01) and Sentennial (SPC 103).

Sovereign, selected in 1990, was named in honor of Queen Elizabeth’s 80th birthday. It matures at Summerland on about August 10, which is a few days after Staccato and about a month after Bing. Average fruit weight (10.8 grams) and firmness (273 grams per millimeter) are similar to Staccato. However, cracking is lower at 18 percent on average, compared with 22 percent for Staccato. The cherry is slightly heart-shaped with a long stem. Cropping tends to be light, even though the variety is self fertile. The tree is vigorous and spreading and appears to be easy to manage.

Sentennial, selected in 1991, matures on about August 11 to 12 in Summerland. Average fruit weight (10.3 grams) and firmness (315g/mm) are similar to Sweetheart. Fruit shape and cracking levels (20 percent) are similar to Sweetheart. The variety is self fertile and sets heavy crops. The tree is vigorous and spreading, and is easy to manage.

All varieties released by the Summerland breeding program are commercialized by the Okanogan Plant Improvement Company. Kappel said he understands that any new releases, including Sovereign and Sentennial, will be available under a limited release system, in a similar way to Staccato, for growers outside Canada. For information on availability of bud wood, contact Ken Haddrell, director of operations for PICO, at (250) 494-5164 or e-mail ken.haddrell@okplant.com.