Effect of Toxins Isolated from Exserohilum monoceras (Drechsler) Leonard and Suggs on Echinochloa crus-galli (L.) Beauv.

Exserohilum monoceras (Drechsler) Leonard and Suggs is a potential biocontrol agent for the control of Echinochloa species. This fungus causes leaf blight in Echinochloa species, but does not damage rice. Phytotoxicity of the fungal fermented broth was evaluated through the bioassay and the active ingredients were preliminarily isolated by using silica gel column chromatography (CC) in this study. The most active fraction 5-III was obtained and analyzed by gas chromatography-mass spectrometry (GC-MS). The results show that 5-III consisted of many compounds, in which 36 compounds accounted for 94.24% of total peak area. Di-n-butyl phthalate (DBP) displayed the highest activity accounted for 9.24% of the total peak area, suggesting that DBP may be one of the main active compounds produced by E. monoceras.