Primocane and Floricane Yield Characteristics of Primocane Fruiting Blackberries From the University of Arkansas Breeding Program Grown In Kentucky

Primocane fruiting blackberries have the potential to produce a niche-market crop for Kentucky growers from late summer until frost. The objective of this study was to determine if advanced selections developed by the University of Arkansas Blackberry Breeding Program were superior to Prime-Jim® and Prime-Jan® in terms of yield and fruit size under Kentucky growing conditions. In June 2006, six selections of primocane fruiting blackberries from the University of Arkansas breeding program (APF-27, APF-40, APF-41, APF-42, APF-46, and APF-77), the commercially available primocane fruiting cultivars Prime-Jim® and Prime-Jan®, and the floricane fruiting cultivar Chickasaw were established at the Kentucky State University Research Farm. In 2007 and 2008, primocane fruit production was evaluated for primocane fruiting selections. Frost damage limited floricane fruit production in the 2007 season. In 2007, the selection APF-40 had the greatest yield (2598 lbs/acre) with Prime-Jim® displaying the smallest yield (295 lbs/acre). Berry weight was significantly larger for the selections APF-40 and APF-41 (about 3.9 grams/berry) than all other selections. In June of 2008, APF-41 and APF-77 produced the largest floricane crops of 4415 and 3717 lbs/acre, respectively, and APF-46 the smallest floricane crop (672 lbs/acre). For the floricane crop, APF-41 and APF-40 had the largest berries of all selections at 6.2 g and 5.0 g, respectively. The 2008 primocane crop began ripening in August. APF-27 had the largest primocane crop in 2008 (3005 lbs/acre); this selection had an almost 2-fold increase in the yield of the previous year. Primocane production from APF-77 (2229 lbs/acre) also increased almost 2-fold in yield compared to the previous year’s primocane crop. Although APF-41 had a large floricane crop in 2008, the primocane crop was only about one-quarter the size of the floricane crop and was about 60% that of the 2007 primocane crop. Primocane fruit of APF-41 were still large in size, but the primocane fruit of this selection were only 4.4 g on average compared to the 6.2 g on average for floricanes in 2008. Even with irrigation, summer drought conditions may have negatively impacted the primocane crop of all selections this year. Chickasaw had a larger yield than the primocane fruiting selections (8259 lbs/acre) and a large berry size (5.4 grams/berry). While some advanced selections appear superior to Prime-Jim® and Prime-Jan®, additional evaluations will be needed before decisions are made on whether any APF selections will be released by the University of Arkansas.