Abstract: This invention relates to the use of C.sub.3 halogenated hydrocarbons alone or in combination with other agronomic adjuvants such as nemiticides, insecticides, fungicides and herbicides for treating agronomic seeds, and mixtures of agronomic seeds with weed seeds to retard weed growth and/or stimulate growth of the agronomic seeds. The method of the invention is particularly useful for treating mixtures of cotton seeds and cocklebur seeds to reduce cocklebur seed germination.