The five members of the Romance series of sour cherries, released in 2003, surround Carmine Jewel, which was released in 1999. All are very dark and sweeter than the tart cherries produced in the United States.
Fruit production doesn’t get much attention at Canada’s 52° north latitude, but plant breeders at the University of Saskatchewan, in Saskatoon, are gaining respect by breeding fruits that are diversifying the prairie farm culture of grain and cattle and affecting fruit growers elsewhere—not only with products but with ideas.
Lacking protection from water bodies like the Great Lakes and hillside slopes to provide air drainage and frost protection, its continental climate is subject to the extreme low temperatures of below -40°F many winters.
Yet, this somewhat forbidding territory in hardiness zone 2 is spawning new varieties of apples, tart cherries (called sour cherries in Canada), and several kinds of berries, plus new cold-hardy plant materials for breeding programs elsewhere.
When University of Saskatchewan fruit breeder Dr. Bob Bors arrived to speak at the Northwest Michigan Horticulture Show in Traverse City in January, few growers were prepared for what seemed to them like a message from the Arctic. At 45° north latitude, the Traverse City growers consider themselves far north and able to grow fruit only because of Lake Michigan’s protection.
But Bors, who is located 500 miles north of them, told how he had successfully bred dwarf sour cherry trees that can be harvested with an off-the-shelf over-the-row berry harvester—something Michigan growers are just beginning to think about. Michigan growers harvest tart cherries mechanically, but they use trunk shakers that are hard on trees. Scientists at Michigan State University have just begun exploring smaller, bushlike trees that could be harvested over the top like blueberries and raspberries.
Bors came to the University of Saskatchewan as its fruit breeder in 1999. He took over breeding programs that were 60 years old and had been designed with the modest goal of producing local fruit under difficult climatic conditions.
“The first batches of cherries brought here from Mongolia had a kill rate of 90 percent,” Bors said. “To get some flavor in the population, the survivors had to be bred with sour cherry varieties from Europe. It took 60 years to find fruit that would both live here and taste good.”
The program has developed locally successful apple varieties, and six tart cherry varieties. It released its first sour cherry, Carmine Jewel, in 1999, and in 2003 followed with the “Romance” series named Romeo, Juliet, Cupid, Valentine, and Crimson Passion. Of these, Bors likes Juliet best for flavor, size, yield, early dormancy, earliness of bloom, and ease of mechanical harvest. In 2004, he wrote a manual telling fruit growers how to grow them.
The dwarf tart cherries are available for nurseries across Canada and from one in the United States—Gardens Alive, Inc., in Lawrenceburg, Indiana.
The cherries are managed as renewable shrubs, much like blueberries where larger, older shoots are pruned out. Some of them are planted “sideways,” the trunks buried along the row with shoots growing up—much like the Upright Fruiting Offshoots Matt Whiting is working with in Washington, but below ground.
The program also maintains the world’s largest collection of saskatoon berry germplasm. Saskatoon is a blueberry-like crop related to apples that has been the number-one fruit crop on the Canadian prairies since the 1980s.
Now, the 200 or so prairie fruit growers want other crops that will extend the fruit season for them and at the same time use the same mechanical harvester. Bors is promoting a trio of fruits in which one harvester costing about $38,000 can be used on about 40 acres of fruit. Three or more crops mean less risk, better cash flow, and steady work, he said.
Bors’s work is focusing on the haskap (a honeysuckle with a blue berry), which ripens in June, a month before saskatoons, and sour cherries, which would harvest in August, a month later than Saskatoons.
Haskap and Saskatoons are bush fruits, hence the desire to cultivate sour cherries not as trees but as bushes.
Sour cherry breeding on the Canadian prairie began in the 1940s, and Bors agrees that he stands on the shoulders of others. Dr. Les Kerr at the University of Saskatchewan began hybridizing using selections from Mongolia and Siberia and crossing them with European varieties, emphasizing hardiness. Fortunately, the hardiest progeny were naturally dwarf bushes that could be grown on their own roots, Bors said. These multistemmed plants may lose wood during frigid winters, but the plants recover even when frozen back. Independent from Kerr, Dr. Stuart Nelson, also at the University of Saskatchewan began evaluating cherries he obtained from Siberia in the early 1980s.
Today, Bors, Rick Sawatzky, and Peter Reimer are using the combined collection to develop varieties with good flavor, size, and yields.
While the Montmorency tart cherry grown in the United States is yellow-fleshed under a red skin, the Saskatchewan cherries are darker red, some almost black. The Canadian varieties are sweeter, combining traits of sweet and sour cherries. While most tart cherries are 10° to 16° Brix, Bors said, the Saskatchewan fruit has scored 16° to 21° and is suitable for eating fresh as well as for processing. The fruit can be canned or frozen for use in pie fillings, baked goods, ice creams, and preserves, but Bors thinks that the future lies in dried cherries and cherry juice—much the same niche that is working for cranberry growers.
The same local processors handle the berries and cherries, Bors said, as well as strawberries and raspberries. “Farms up here average 3,000 acres in size,” he said. “Many of these farmers are willing to devote 20 or 30 acres to experimenting with fruit crops.”
Given the isolation of the prairie orchards, disease and insect pressure is very low. “Diseases are extremely rare in Saskatchewan,” Bors said. “It is not known if this is due to resistance or avoidance. If you can get fruit to live here, you will hardly have any insect or disease problems.”