When a referendum has been authorized as provided in Section 2-8-85, the certified association shall, not less than 30 days before the date for such referendum, publicly announce the date, hours, polling places and rules for voting in the referendum, the amount and basis of the assessment proposed to be collected, the means by which such assessment shall be collected and the general purposes for which said amount so collected shall be expended and applied. Such notice shall be published by the certified association through the medium of an established farm publication, and written notice thereof shall be given to each county agent in the area covered by the referendum.