Resistance genes Ryadg and Rysto have been used extensively in breeding for extreme resistance to Potato Virus Y (PVY) in the Northwest (Tri-State) Potato Variety Development Program. Payette Russet and Castle Russet are examples of Tri-State varieties having extreme resistance to PVY conferred by Rysto. An additional gene for extreme resistance, Rychc, was not thought to be present in Tri-State germplasm until the utilization of a recently developed multiplex marker assay detected the presence of Rychc in six breeding clones: PALB0302-1, PALB303-1, PALB03016-3, PALB03016-6, PALB03035-7, and PA01N32-1. These clones originated from hybridizations conducted at Prosser, WA with their subsequent selection in the field at Aberdeen, ID for long tuber shape and russet skin. While PVY resistance was known to be present in this germplasm it was not previously known that it was conferred by Rychc. In addition to extreme resistance to PVY, several of the clones have also been utilized in the Aberdeen breeding program as parental material for their resistance to late blight as well as resistance to cold-induced sweetening following storage at temperatures as low as 4.4o C. PALB03016-3 and PALB03016-6 also have shown higher levels of terpenoids in the foliage which may contribute to observed reductions in potato psyllid oviposition and green peach aphid reproduction.