In their opinion paper "The unpredictable risk imposed by microbial secondary metabolites: how safe is biological control of plant diseases?" (J. Plant Dis. Prot. 124, 413-419; https://doi.org/10.1007/s41348-017-0109-5), H.B. Deising, I. Gase and Y. Kubo criticize the use of microbial pesticides in plant protection. They point to the ability of microorganisms to form toxic metabolites and fear severe health problems when antagonistic microorganisms are increasingly released into agro-ecosystems. In our opinion, this view fails to reflect the reality because it largely ignores the ecology of microorganisms. In this contribution, we state reasons why biocontrol of plant diseases is a safe technology.