High Risk Strawberry Viruses by Region in the United States and Canada: Implications for Certification, Nurseries, and Fruit Production.

There is limited information about the distribution of strawberry viruses in North America and around the world. Since the turn of the century, there has been a concerted effort to develop sensitive tests for many of the previously uncharacterized, graft-transmissible agents infecting strawberry. These tests were employed to determine the presence of strawberry viruses in major strawberry production and nursery areas of North America. The viruses evaluated in this study were Apple mosaic, Beet pseudo-yellows, Fragaria chiloensis latent, Strawberry chlorotic fleck, Strawberry crinkle, Strawberry latent ring spot, Strawberry mild yellow edge, Strawberry mottle, Strawberry necrotic shock, Strawberry pallidosis, Strawberry vein banding, and Tobacco streak. The aphid-borne viruses were predominant in the Pacific Northwest whereas the whitefly-borne viruses were prevalent in California, the Midwest, and the Southeast. In the Northeast, the aphid-transmitted Strawberry mottle and Strawberry mild yellow edge viruses along with the whitefly-transmitted viruses were most common. The incidence of pollen-borne viruses was low in most areas, with Strawberry necrotic shock being the most prevalent virus of this group. These results indicate that there are hotspots for individual virus groups that normally coincide with the presence of the vectors. The information presented highlights the high-risk viruses for nursery production, where efforts are made to control all viruses, and fruit production, where efforts are made to control virus diseases.