Land requirements for the production of white clover and trefoil seed are as follows:
(1) Breeder seed for the production of white clover or trefoil foundation seed must not be planted on land on which the same kind has been previously planted. During the year prior to white clover or trefoil seeding, the land must be in a cultivated crop or fallow and the land must be free from volunteer plants as determined by a field inspection during the season in which the seedling is established.
(2) Foundation seed for the production of registered or certified white clover or trefoil seed must be planted on land on which no other variety or strain of the same kind is grown or planted during the season in which the seedling is established.
(3) Foundation or registered trefoil seed for the production of certified seed shall be planted on land on which no other variety or strain of trefoil is grown or planted during the three years prior to planting.
(4) Reseeding of a white clover or trefoil seed field due to failure or partial failure of the first seeding may be done by referring to the guidelines in WAC 16-302-045
(5) Certification of trefoil shall be limited to stands not exceeding five years of age, except for a variety grown outside its region of adaptation, in which case certification shall be limited to stands not exceeding three years of age.
(6) Foundation or certified producing white clover fields are eligible for certification for only two harvest years following the year of seeding if the seed production the first year is prevented. Foundation fields may be reclassified to the next lower class after being harvested for seed for two years.
(7) Ditchbanks, roadways, etc., adjacent to a certified white clover or trefoil field must be free of volunteer plants of the same kind and prohibited noxious weeds.
(8) Volunteer plants in the white clover or trefoil field may be cause for rejection or reclassification of the seed field.
(9) No manure or other contaminating materials may be applied during the establishment and production period of the white clover or trefoil stand.