Seeds treated with a mercurial or similarly toxic pesticide, if any amount remains on or in the seed, shall be labeled with the skull and crossbones and a statement such as: "This seed has been treated with poison," "treated with poison," "poison treated," or "poison" with the word "poison" in red on a contrasting background. The word "poison" shall appear in not less than 8 point type, and the skull and crossbones shall not be less than twice the size of the type used for information required to be on the label. In making this determination, the department shall be guided by the labeling registered by the Environmental Protection Agency and/or Washington state department of agriculture on the pesticide being used and by the requirements of the Federal Seed Act, as revised January 1, 1998.