The invention relates to improved methods of hybrid seed production. More particularly it relates to the use of one (or two) phytotoxic chemical resistant genes in the male (and female) parent in a hybridization process, followed by uncontrolled pollination and dosing the resultant hybrids with the one (or two) phytotoxic chemicals to eliminate plants arising from unwanted contaminating seeds and thus producing pure F.sub.1 hybrids.