21—43.2 (200) Warning required. When any product which contains 0.03 percent or more of boron in a water-soluble form or 0.001 percent or more of molybdenum is incorporated in a commercial fertilizer a special warning tag or statement must be furnished to the purchaser. This tag or statement shall carry the word “WARNING” in letters at least one inch in height; it shall state the crops for which the fertilizer is to be used and it shall state that use of the fertilizer on any other than those recommended may result in serious injury to the crops. The tag or statement is to be attached to or printed on the bag or other container in which the fertilizer is sold; for bulk fertilizers the statement must be placed on the invoice or other document which shall accompany delivery and be supplied to the purchaser at the time of delivery as provided in Iowa Code section 200.6(2).