Distribution of tobacco streak, tomato ringspot, and raspberry bushy dwarf viruses in Rubus ursinus and R-leucodermis collected from the Pacific Northwest

Clonal and seed propagules of Rubus ursinus, the trailing blackberry, and seed of R. leucodermis, the western black raspberry, were collected from throughout the Pacific Northwest (Oregon, Washington, and British Columbia). The collections were made in four general environmental regions: at sea level along the Pacific coast, in the coastal mountains adjacent to the coast, in the Willamette Valley, and in the Cascade Mountains. After the resulting propagules were established, leaves were tested by enzyme-linked immunosorbent assay according to standard procedures. None of the R. leucodermis samples tested positive for raspberry bushy dwarf idaeovirus (RBDV), tomato ringspot nepovirus (TomRV), or tobacco streak ilarvirus (TSV). Rubus leucodermis is either resistant to these viruses or their vectors, the viruses are not seed transmitted in this species, or the viruses were not detected due to inadequate sampling. No samples of R. ursinus tested positive for RBDV or TomRV. Samples from 77% of the sites where cuttings were taken and 37% of the seedling populations tested positive for TSV. Along the Pacific coast, only 20% of the sites sampled by cuttings tested positive for TSV. However, the percentage of infected sites where cuttings were taken increased to 88 and 100% in the coastal mountains and the Cascade Mountains, respectively. Along the Pacific coast, 14% of seedling sites tested positive for TSV The number of TSV positive seedling sites increased to 45 and 36% in the Cascade Mountains and the coastal mountains, respectively. The Willamette Valley site tested negative for TSV. With one exception, all of the low elevation sites tested negative for TSV Prevailing winds or earlier flowering may prevent some of these Pacific Coast populations from becoming infected. Many of the TSV positive sites had some samples that tested negative, indicating that TSV is unevenly distributed within these populations.