The broad mite (Polyphagotarsonemus latus) was found in association with leaf-curling symptoms on primocane-fruiting blackberry (Rubus rubus) in Arkansas in 2007–2009. Broad mite had not been previously reported on blackberry. The plots sampled in this study were part of a study comparing harvesting in the fall versus harvest in spring and fall, high tunnels versus ambient conditions, and three genotypes, all under organic production. Leaves were sampled, broad mites per leaf counted, and leaf area and trichome density measured. Results indicated that broad mite is capable of overwintering in a moderate temperate climate and that it reduces leaf area of primocane-fruiting blackberry. The fall-only harvest system had fewer broad mites than fall and spring harvest. There were a range of genotype effects on broad mite populations, including one genotype, ‘Prime-Jan®’, on which broad mite populations remained low, and one genotype, APF-46, on which mite populations grew significantly. Observations indicate that the broad mite may be a pest of ‘Prime-Ark® 45’, another primocane-fruiting cultivar.