Herbicidal properties of the thaxtomin group of phytotoxins.

The thaxtomins are a group of phytotoxins generated by the bacterium Streptomyces scabies (the main causal organism of potato common scab). Available members of the group were assessed for herbicidal activity by a variety of standard tests. Test results indicated that thaxtomin A, the predominant member, was also the most physiologically active. Injury symptoms in most instances were similar to those caused by known cellulose biosynthetic inhibitors such as dichlobenil and isoxaben. Although test results indicated that the thaxtomins had many of the biological properties desirable in a commercial herbicide, they nevertheless lacked the systemic phytotoxicity critical to deliver reliable weed control at low rates.