It is unlawful for any person in this state knowingly to permit any seriously injurious insects or plant diseases that have been or may be declared by the director to be public nuisances by reason of being plant pests, to exist on his or her premises, unless efforts are being made to eradicate the plant pests as may exist, or to sell, offer for sale, give away, or otherwise distribute any plant infected or infested by or with the plant pests.