Blackberry plant named `APF-77`

Description and specifications of a new and distinct blackberry cultivar named `APF-77` which originated from seed produced by a hand pollinated cross of APF-12 (U.S. Plant Pat. No. 16,989) x Arapaho (U.S. Plant Pat. No. 8,510) is provided. This new blackberry cultivar can be distinguished by its primocane-fruiting trait with attractive, large fruit with excellent flavor, excellent plant health, and erect canes and enhanced performance for fruit set and development in high summer temperatures