Late Blight infection and Soft Rot must be below established tolerances. Levels of other defects, such as Hollow Heart and Growth cracks, are also established. In Washington, the State Potato Commission funds seed lot trials which are conducted by scientists at Washington State University. Both seed potato and commercial potato growers provide seed samples which are then planted in the state's commercial growing area. The results of the seed trials are made available to the public.
Commercial growers can then select the highest quality seed.