Yield Characteristics of Thorny Primocane-Fruiting Blackberries from the University of Arkansas Breeding Program Grown Under Organic Growing Conditions in Kentucky

Abstract

Primocane-fruiting blackberries have the potential to produce a niche-market crop for blackberry growers from late summer until autumn frost as primocanes, and again as floricanes the following season. The objective of this study was to determine if advanced selections developed by the University of Arkansas (UA) Blackberry Breeding Program were superior to Prime-Jim® and Prime-Jan® in terms of yield and fruit size in Kentucky growing conditions and maintained with national organic program standards. In June 2006, six selections of primocane-fruiting blackberries from the UA 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 planted at the Kentucky State University Research Farm using 6 month old tissue cultured plants. The planting was managed for both floricane and primocane production. In both 2007 and 2009, frost damage, winter injury, and anthracnose limited floricane fruit production. In the second season (2007), APF-40 had the greatest primocane yield, and berry weight was larger for APF-40 and APF-41 than other selections. In the third season (2008), APF-41 and APF-77 produced the largest floricane yield, and APF-41 and APF-40 had the largest berries of all selections. APF-27, Prime-Jan®, and APF-77 had greater primocane yields in the third season (2008) than APF-41 and Prime-Jim®; APF-40 and APF-41 tended to produced the largest berry weight. In the fourth season (2009), floricane yields were small for all selections; however, primocane yields and fruit weights were greater for all selections than for Prime-Jan®. ‘Chickasaw’ had higher yields and larger berry size than the primocane-fruiting selections. Prime-Jim® had consistently lower yields and berry sizes than the advanced selections. Prime-Jan® was superior to Prime-Jim®, but lower than APF-77 in terms of yield and berry size. Prime-Jan® can be recommended for home garden use. APF-77 (now marketed as Black Magic™ in the United States) can be recommended for home growers and has commercial value for local markets including pick-your-own or on-farm sales that require no or only limited fruit storage time.