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TECHNICAL SESSION: From virus biology to management strategies

Changes in prevalence of Potato virus Y strains in seed potato in Idaho and Washington, 2016-2019
Alexander Karasev - University of Idaho. Kelsie Green- University of Idaho, Cassandra Funke- University of Idaho, Lisa Tran- University of Idaho, Chris Benedict- WSU, Olga Nikolaeva- Univ of Idaho

Potato virus Y (PVY) exists as a complex of strains, with multiple recombinants associated with tuber damage. Prevalence of strains was studied in the Idaho and Washington seed potato winter grow-out (WGO) trials, between 2016 to 2019. Foliar potato samples exhibiting mosaic during the WGO trials were collected and subjected to serological and molecular analyses using monoclonal antibodies and two sets of strain-specific primers probing most common recombinant junctions in PVY recombinants. In Idaho, prevalence of the non-recombinant strain PVYO was stable at around 3%, while the most prevalent strain of PVY was found to be PVYN-Wi, at approximately 70%, followed by PVYNTNa, at around 20%, with little changes during the period of observation. In the 2019 season, the latter two recombinants, PVYN-Wi and PVYNTNa together, represented more than 90% of all PVY positives found in Idaho seed potato lots. In Washington, a drastic transition occurred, from mostly non-recombinant PVYO and PVYN strains in 2016, to mainly PVYN-Wi and PVYNTNa strains in 2019. The contrasting strain compositions of PVY in Idaho and Washington seed potato may reflect very different production practices between specialty potato cultivars grown in western Washington, and processing potato cultivars grown in Idaho.