Investigations into the cytokinin‐like properties of benzimidazole ‐derived fungicides

SUMMARY Of seven systemic benzimidazole fungicides tested, four showed cytokinin activity in a modified Amaranthus betacyanin bioassay. In the presence of the gibberellins A 4 and A 7 , in the dark at 25°C, the four active compounds stimulated the germination of seeds of two celery cultivars dependent on cytokinin for germination under these conditions. One cytokinin‐active fungicide was methyl benzimidazol‐2‐yl carbamate (MBC) and the other three break down into this compound in solution. The three inactive fungicides do not. However, the hormonal properties of the cytokinin‐active fungicides may not be due to the MBC moiety alone because sometimes they were more cytokinin‐active than pure MBC.