John Clark likes the idea of enjoying a fresh blackberry cobbler in the fall. “A cobbler served up beside a fresh pecan pie would be like a slice of heaven,” he said.

Clark, fruit breeder for the Arkansas Agricultural Experiment Station, is developing new blackberry varieties that can provide just that sort of autumnal luxury. He gave a preview of two primocane-fruiting blackberries he expects to release later this year to visitors touring the University of Arkansas Fruit Substation during a fruit field day at the Clarksville, Ark., station in June.

Clark discussed how primocane blackberries can add a fall crop to the traditionally spring fruit.

“This is something you've never seen before,” he told the visitors, holding up a flowering primocane. “Anywhere I go to speak about fruit breeding, in the United States or abroad, when I mention primocane-fruiting blackberries, ears perk up. Foreign fruit breeders and producers suddenly learn how to speak English, because they get excited about the possibilities.”

Blackberries have a perennial root system and biennial canes, Clark said. The roots live for several years, but above ground, the canes live for just two. Each year, the plant grows new canes, called primocanes, that neither flower nor fruit during their first year. These canes are called floricanes in their second year, when they do flower and fruit. Then they die. Each year, the plant grows new primocanes to replace the dying floricanes.

On the new plants Clark plans to release in the fall, the primocanes do flower and bear fruit, but in the fall after the new cane has matured. On these plants, the floricanes produce berries in the spring and the primocanes produce fruit in the fall — essentially two crops from the same plants.

“Among the advantages of primocane-fruiting blackberries is the ability to grow a crop in cooler climates where harsh winters normally kill the canes,” Clark said. “You could simply mow the canes down after harvest and the new canes would produce berries the next year.”

Mowing the plants down after a fall harvest may even prove to be cost-saving compared to the laborious pruning required to remove dead canes in conventional blackberry production, he said.

Clark said the two varieties he plans to release this year have had mixed results in Arkansas. “Our hot summers hurt flowering and fruit set, which cuts yield,” he said. “The floricane crop is very early ripening, and that has merit. But they perform as primocane-fruiters very well in more moderate climates, such as you find in Oregon, the leading state in U.S. blackberry production.”

Adapting the primocane blackberries to Arkansas is a trait Clark said he is vigorously pursuing. He is also working on developing thornless primocane varieties.

“Our primary goals are to develop fruit varieties that improve profitability for Arkansas growers and satisfy the tastes of Arkansas consumers,” he said. “These new varieties give us a starting place for developing other varieties that meet those goals.

“In the meantime, marketing them to other regions where they already do well will help bring revenue into the Arkansas fruit breeding program that helps us achieve those goals.”


Fred Miller is science editor for the Arkansas Agricultural Experiment Station. e-mail: fmiller@uark.edu.