Bipolaroxin, a selective phytotoxin produced by Bipolaris cynodontis.

Two sesquiterpenes have been isolated from the fungal pathogen of Bermuda grass Bipolaris cynodontis. Chemical, spectral, and x-ray diffraction studies have led to the characterization of these as bipolaroxin and dihydrobipolaroxin, highly oxygenated members of the eremophilane family. Bipolaroxin is phytotoxic to some but not all of the plants tested. To our knowledge, a phytotoxin with host selectivity isolated from a weed pathogen has not been reported previously.