Compositions and methods for indirectly reducing incidence of fungal pathogen infection in a plant are disclosed, wherein the fungal pathogen may be Botrytis, Macrophomina, Rhizoctonia, Sclerotinia, or Verticillium. The compositions comprise pasteurized microalgae cells in an amount effective to reduce incidence of the fungal pathogen in a plant compared to a substantially identical population of untreated plants. The composition treatment can include at least one microalgae such as Aurantiochytrium, Galdieria, Scenedesmus, Haematococcus, Isochrysis, Spirulina or any combination thereof.