Black Diamond thornless trailing blackberry at the North Willamette Research & Extension Center in Aurora, Oreg. Black Diamond, introduced in 2005, was bred by a team led by Chad E. Finn of the U.S. Department of Agriculture. It is high-yielding, vigorous, adapted to machine harvesting and produces a very good processed product, although the flavor is not quite as good as Marion, the industry standard. In addition, the fruit are firm enough to be suited to some fresh market uses. (David Karp / For The Times)