Newswise — The University of Arkansas Division of Agriculture has released the world's first commercial blackberries that will produce both spring and fall crops.
"Prime-Jimâ„¢" and "Prime-Janâ„¢" are primocane-fruiting blackberries, said John R. Clark, fruit breeder for the Arkansas Agricultural Experiment Station. Unlike other blackberries, primocane-fruiting blackberries produce both a spring crop and a fall crop of fruit.
"These are unique plants," Clark said. "I'm not aware of anyone else who has anything like them."
All other blackberries in production now have a perennial root system with biennial canes. Each year, the plant grows new canes, called primocanes, that neither flower nor fruit, Clark said. These canes become floricanes in their second year, when they do flower and produce fruit. Then they die. Each year, the plant grows new primocanes to replace the dying floricanes.
The primocanes on Prime-Jimâ„¢ and Prime-Janâ„¢ flower and bear fruit, but in the mid- to late-summer and fall after the new cane has matured. On these plants, the floricanes produce berries in early June and the primocanes produce fruit beginning in mid-July and continuing until frost.
"Primocane fruiting opens all kinds of opportunities for creative growers," Clark said. "It allows blackberries to be grown in colder climates where the canes can't survive over winter. You can just mow them down in the winter and let the primocanes grow and produce berries the following year."
In more moderate climates, the plants produce two crops a year, extending the growing season, he said. Producers can also schedule crops by keeping the canes cut down until they're ready to let them grow and begin fruiting.
Prime-Jimâ„¢ and Prime-Janâ„¢ are named for Dr. James N. Moore, who founded the U of A fruit breeding program, and his wife, Janita. Dr. Moore directed the fruit breeding program for 33 years and began the work that led to the development of primocane-fruiting blackberries.
They are thorny varieties with floricane berries averaging about 5 grams. (Wild blackberries typically weigh about 1 gram.) The primocane berries are a little smaller in Arkansas. Like other thorny varieties, Clark said, these blackberries do not store well for shipping and are most suitable for home gardens and on-farm sales.
He said the primocane berries are better suited for moderate climates and produce more consistent results in northern Arkansas than other parts of the state.
"Arkansas' hot summer temperatures can interfere with fruit-set," Clark said.
Quite by accident, he discovered the primocane berries flourish in states with more moderate climates. In test plots in Oregon, the U of A berries grew as big as 10 grams. "I couldn't believe the size of the berries they were growing on our plants in Oregon," Clark said.
For Arkansas growers, Prime-Jimâ„¢ and Prime-Janâ„¢ offer a novelty fruit and potential for improvement.
"These first two primocane-fruiting blackberries give us a good starting point from which to develop varieties with better adaptation to Arkansas," Clark said. "We're continuing to breed these for better heat tolerance as well as for thornless plants."
Prime-Jimâ„¢ and Prime-Janâ„¢ are available now to licensed propagators and will be available to nurseries in the fall, he said. More information about these and other U of A fruit varieties is available on the Web:http://aragriculture.org/horticulture/fruits_nuts/default.asp
blackberry crossing13.jpg (color, 200 DPI):Despite threatening weather, fruit breeder John R. Clark emasculates blackberry flowers to prepare them for crossbreeding. The fruit-breeding program at the University of Arkansas Division of Agriculture has developed two varieties of primocane-fruiting blackberries that produce two crops of berries. The first ripens in the spring and the second crop ripens beginning in mid-summer and continuing until first frost.
Primocane90.jpg (color, 200 DPI):Primocane-fruiting blackberries, developed at the University of Arkansas Division of Agriculture, offer two crops a year. These spring berries have ripened even as the plants bloom for the mid- to late-summer crop.
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