What does the published scientific research say about Phoma macrostoma?

Five peer-reviewed PubMed records address Phoma macrostoma (syn. Didymella macrostoma) as a bioherbicide and biocontrol candidate. The literature documents commercial products registered in Canada and the United States — marketed as Phoma and BioPhoma — for control of perennial dicotyledonous weeds, principally Canada thistle (Cirsium arvense), via the characteristic white tip disease. Separate field reports describe the fungus causing root and crown disease in hoary cress (Lepidium draba) in Montana and leaf spot on Conyza sumatrensis in China, both evaluated in the published record as potential biocontrol applications.

The fungus produces macrocidin A and macrocidin Z, phytotoxic secondary metabolites detected in infected plant tissue and culture extracts. Reported in the peer-reviewed literature, these compounds show low antimicrobial and cytotoxic activity and no entomotoxic properties. One in vitro study separately reported a Phoma macrostoma endophyte from water mint increased root area and depth in Arabidopsis at 21 days post-inoculation — cited in that paper as plant-growth-promoting behavior under laboratory conditions only.