Abstract: Up to now, scientists are still using the way of living hosts to determine the physiologic specialization and pathogenicity of the rust fungi, no foundamentally new change has been made.Differential hosts of wheat stripe rust, consisting of important cultivars and sources of resistance used in China, have the same ability to discriminate as the international differential hosts. A physiologic race may consist of one biotype or a group of biotypes. Among strains in the same race, there are characters in general as well as characters in difference. It seems to author that the characters in general are of ma major importance, however, there is significant diffecence in pathogenicity between races.It is proposed that three steps should be taken to characterize a new race: 1, to investigate in fields; 2, to identify the collected samples by means of differential hosts; 3, to study the pathogenicity of a new race at the adult stage of wheat.The merits and the demerits of traditional research methods are commented. It is suggested that the differential hosts of wheat rusts should include a set of monogenic lines, major commercial cultivars and the varieties with important sourse of resistance. It seems that using the method of virulence frequency analysis alone can not replace the traditional way practically.

Key words: Differential hosts, Physiologic race, Resistance of adult plants