Fields of all classes of hybrid or open pollinated sunflowers must be isolated from all other sunflower fields, noncertified sunflower production including home garden plantings, and all wild-type sunflowers by a distance of one and one-fourth miles except for fields within the Columbia Basin irrigation project which must be isolated from the above by two miles. Isolation is not required for fields utilizing the same restorer line.
Wash. Admin. Code § 16-302-805