Abstract:  Helminthosporium gramineum was isolated from infected barnyard grass and considered as a potential biocontrol candidate based on its epidemiological traits and crop safety. Its conidia showed great promise as a bioherbicidal agent for control of barnyard grass in rice fields. Thus， this study was conducted to screen conidia adjuvants for bioherbicidal fungus H.gramineum based on the biological compatibility， dispersion force， stability and other evaluation indictors. The results showed that there was better biological compatibility when SP-20， soybean oil and CMC were considered as surfactants， vegetable oil adjuvant and stabilizer, respectively. They did not significantly inhibit the mycelia growth and conidia germination. The dispersion index （I） of conidia suspensions was 0094 after addition of SP-20 as surfactants， which indicated higher dispersion force. The slope of linear fitting was minimal as 0.232 when CMC was used as stabilizer， which showed better stability. These results of adjuvants would be helpful for developing H.gramineum formulations.

Key words: biological control, barnyard grass, fungi, surfactant, stabilizer, vegetable oil adjuvant