Potato Cultivars Differ in Current Season Potato Virus Y (PVY) Infection

Research plots were established in 2004, 2005, and 2006 at Hermiston, Oregon and in 2005 and 2006 in Othello, Washington to determine if potato cultivars differ in current season PVY infection. Eight potato cultivars were used; Gem Russet, GemStar Russet, Russet Norkotah, Shepody, Alturas, Ranger Russet, Umatilla Russet and Russet Burbank. The first four listed produce mild symptoms due to current season infection with PVY. Cultivars were planted in a randomized complete block design with four replications where each block contained a single 50-hill row for each cultivar. Leaf samples were evaluated monthly via ELISA to follow naturally occurring PVY infection. Cultivars that produce mild symptoms had higher current season infection levels. Over the 3 years at Hermiston, Shepody (93.8%), Gem (92.8%), Gemstar (89.8%) and Russet Norkotah (82.7%) had the highest infection levels, while Russet Burbank (68.8%), Umatilla Russet (58.0%), Ranger Russet (49.6%) and Alturas (48.1%) had the least infection. At Othello, infection levels were much lower and cultivar differences were minimal though Gem Russet had the highest current season infection (30.4%), Ranger Russet had the lowest (4.9%) and was significantly lower than Gem Russet and Shepody. Higher levels of infection occurred in 2006 at Hermiston and Othello (77.1% and 18.2%, respectively) compared to 2005 (66.7% and 10.2%, respectively). This is the first report where different cultivars of potatoes, growing side by side, had different levels of PVY infection. Possible explanations for differing current season infection levels between cultivars are discussed.