Technical Abstract: Wild Treasure is a new trailing blackberry cultivar from the U.S. Department of Agriculture-Agricultural Research Service breeding program in Corvallis, OR, released in cooperation with Oregon State University. Wild Treasure is thornless and has high quality fruit that are very small and can be mechanically harvested. The fruit is of particular value for market niches where small fruit size is perceived as superior such as in bakery products using whole berries and in frozen poly-bag fruit blends where large-fruited blackberries are out of proportion in size to the other components of the mix. Wild Treasure is named to recognize its pedigree as it is a first generation selection out of a cross between a thornless cultivar and a selection (GP 9-24) of the western dewberry, Rubus ursinus that was collected as fruit from Mount Hebo (Oregon). An extensive collection of Rubus ursinus germplasm was made throughout the Northwest and planted in a common garden for evaluation. Rubus ursinus offers several traits of interest to breeding programs including outstanding flavor and fruit quality, early ripening, flexible canes, and good vigor. Many of the characteristics that have made Marion blackberry the commercial standard for fruit processing, including aromatic flavor and less noticeable seeds, can be traced back to R. ursinus parents. However, R. ursinus in a monoculture is susceptible to foliar and cane diseases. This and its dioecious nature make it difficult to commercialize this species. Wild Treasure, tested as ORUS 1843-3, was selected in 1998 from a cross of GP 9-24 and Waldo. GP 9-24 was originally selected for its larger fruit size, low foliar disease incidence and high fruit number. Waldo is a very high quality thornless blackberry with excellent foliar disease resistance, medium large fruit, high yield, and short internodes that cause a somewhat dwarfed plant with brittle canes. Selections from this cross had the superior fruit quality and vigorous growth habit of R. ursinus combined with the good disease tolerance and thornlessness of Waldo.