Triazine resistance is reported to be due to chloroplast herbicide target insensitivity in most species, and this is most often caused by a Ser264-Gly mutation at the D1 protein. In order to ascertain whether this mutation is really predominant amongst resistant plants, and also for gene flow studies, a rapid test is needed that allows the testing of large quantities of plants. Here a bidirectional allele-specific PCR (polymerase chain reaction) identification is proposed. The designed primers were shown to be universal in the three grass and three broadleaf species examined. Copyright © 2006 Society of Chemical Industry