Mar 27, 2014
Arkansas blackberry breeding effort flourishing

Arkansas fruit breeding has been in full swing for 50 years. Based on recent successes, there are indications the program will continue to thrive well into the future.

The Arkansas blackberry breeding program was on full display during a talk by John Clark, a fruit breeder with the University of Arkansas, at the SE Regional Fruit & Vegetable Conference in Savannah, Ga., in January.

Clark touted Prime-Ark Freedom, a new variety developed by the University of Arkansas (UA), that is the world’s first thornless primocane-fruiting blackberry. But he acknowledged its widespread commercial application remains somewhat limited.

Although initial evaluations for postharvest storage potential indicate that Prime-Ark Freedom is not well suited for storage and shipping, it should be desirable for use in home gardens and local commercial markets, Clark said.

“The potential for PA Freedom is intended for home garden use due to the fact it does not store well for shipping – or that is what we think at this point. It might work for local markets,” Clark said.

Freedom is the fourth in the university’s Prime-Ark line of primocane-fruiting blackberries, which flower and fruit on each season’s new branches, called primocanes. Most blackberries only bear fruit on second-season canes, known as floricanes.

Other Arkansas blackberry variety considerations include, in the order of ripening at the location in Clarksville, Ark.: Natchez, June 5; Osage, June 10; Ouachita, June 12; Navaho, June 20; and Apache, June 25.

Clark reviewed Osage – the newest thornless floricane-fruiting blackberry. In Arkansas, Osage ripens between Natchez and Ouachita, with June 10 the beginning harvest date. Its yields have been consistent and good, comparable to and higher than Ouachita. Berry size is medium, 5 g., slightly smaller than Ouachita.

“Flavor is a key attribute of Osage, having lower acid flavor with notable flavor components coupled with high soluble solids,” Clark said. “It’s good even on bad flavor days. It has great postharvest handling potential.”

Osage should be considered a complement to Ouachita in size and season to diversify cultivars for this harvest period. It’s consistently uniform in droplet fill, whereas Ouachita can have uneven fill. Osage is available now from propagators and has completed all virus testing.

When determining what varieties to pursue, Clark said, growers should look at the order of ripening and the fruit characteristics:

  • Natchez is an early, large, popular, sometimes tart variety; not as erect.
  • Ouachita remains the top Arkansas variety.
  • Navaho tends to be older and smaller, but good for late-season and excellent quality. It is susceptible to orange rust.
  • With Apache “some like it, some don’t, and the reason is white drupes.” It’s not for shipping and may require shift-trellis assistance.
  • Von is a variety to consider for later season.

So, what’s coming in Arkansas blackberries?

“Some very nice complements to early season Natchez are showing promise,” Clark said. “Exceptional firmness is now incorporated into thornless plants with a crisp-like texture.

He said the floricane crop is being used by some growers as an early option (near Natchez) and is “very firm with good quality.”

Yields can be “substantial,” he said, noting “the less PC crop the year before, the greater the FC crop potential.”

When looking at primocane-fruiting varieties in heat, Clark reported breeding is being done in a very hot climate, with 2011 and 2012 being the hottest ever in Arkansas.

“Unfortunately, progress thought to be made was not confirmed or supported these years,” he said.

He said options for crop protection could include shade cloth, rotating cross-arm trellises or pursuing a floricane crop that is early and produces high-quality berries.

Clark offered tips for Natchez crop control.

“Be very careful about keeping cane length regulated in pruning,” he said. “Don’t let main/terminal canes grow excessively long. Make sure laterals are shortened to 15 to 20 inches in dormant pruning.

“I suspect some have found Natchez harder to manage due to it being less erect,” he said. “Lateral shoots can grow excessively long and make the pruning effort greater.”

Harvest techniques for Natchez could include harvesting early in the day and stopping in late morning.

“Be careful about moving fruit quickly to cold storage,” he said.

A rotatable cross-arm trellis has shown some major reductions in white drupes in the later season Apache, Clark said.

“This variety always had great flavor, postharvest handling, size, crop potential, plus later ripening,” he said.

Gary Pullano





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