Prime-Jim

Prime-Jim (patented as APF-12) was the second commercial variety of primocane-fruiting blackberry. This type of fruiting habit has the potential to revolutionize blackberry production much-like that occurring in primocane-fruiting red raspberries. This blackberry variety was intended primarily for home-garden production and for limited commercial trial evaluations. Name of Prime-Jim was selected to honor Janita and James N. Moore, who founded the University of Arkansas fruit breeding program in 1964.
Canes of Prime-Jim are thorny and erect, vigorous. If primocanes are tipped at 1 to 1.3 m to control length and encourage lateral branching, Prime-Jim can be grown in a hedgerow without trellis support. However, support of canes during fruiting is recommended.
Average yield on floricanes is about 13 t/ha, on primocanes - about 3 t/ha.
Average berry weight on floricanes and primocanes is about 5 g. Berries of Prime-Jim are blocky, conical, black with glossy finish. Fruit shape varies on primocanes and quality factors including glossiness and color are affected by heat. Also observed doubled fruits.
Floricane bloom date is the end of April or beginning of May, primocane bloom date is the middle of June. Floricane harvest date is the second week of June, primocane first ripe fruit date is the third week of July. Flowering continues until first frosts.
High air temperature can cause profound reductions in flowering.
This variety requires winter shelter, winter hardiness is about minus 13 C.