Marie Beatrice Schwarz was born on 12 July 1898 in Batavia in the Dutch East Indies (present-day Jakarta, Indonesia).

She studied at the Utrecht University in the Netherlands, where she was Johanna Westerdijk's first PhD student.

[2][3] Schwarz spent most of her early professional life studying pathogens afflicting the groundnut Arachis hypogaea at the agricultural research station in Bogor.

After liberation, Schwarz and her two sons returned to the Netherlands, where she joined the Centraal Bureau voor Schimmelcultures (Central Bureau for Fungus Cultures) in Baarn,[4] studying various fungi and writing a monograph on the genus Epicoccum.

Shortly before her death in 1969, she was made an Officer in the Order of Orange Nassau in recognition of her contribution to phytopathology [5] Schwarz died on 27 July 1969, at the age of 71, in Baarn.