Johanna Westerdijk

In 1917 Johanna Westerdijk became the first woman to hold a professorship in the Netherlands. Her chair of plant pathology at Utrecht University was, however, only part of her work. She already directed the Centraalbureau voor Schimmelcultures — today the collection of the Westerdijk Fungal Biodiversity Institute — and the Willie Commelin Scholten plant disease laboratory. In both she built the infrastructure without which a single observation of a fungus quickly vanishes: a holding of living, described and comparable strains.

A fungal culture in a collection is not an ornament, nor a herbarium specimen. It has to stay alive, pure, correctly identified and linked to documentation. Westerdijk developed a system of exchanging cultures between laboratories, through which researchers could work on the same material. That reduced the problem of names used for different organisms and made experiments on plant pathogens repeatable.

Her team worked on Dutch elm disease, among other subjects. Laboratory research helped establish the fungal cause of the disease and to distinguish the pathogen from other microorganisms present in dying tissue. Westerdijk combined diagnostics with teaching: 56 people completed doctorates under her supervision, and almost half were women. In the conditions of the first half of the twentieth century, the laboratory gave them a rare opportunity for an independent scientific career.

Utrecht University also describes her as an organiser with a strong sense of community. The laboratory's well-known motto held that for outstanding minds the art is to mix work and play. Her achievement should not, however, be reduced to a colourful anecdote about the first woman professor. The lasting result was a way of doing science: a reference collection, a network of collaboration, the training of specialists, and a close connection between taxonomy and plant disease.

The institute bearing her name holds tens of thousands of cultures of fungi, yeasts and bacteria today. The material is used for identification, sequencing, and medical, agricultural and industrial research. The scale is new, but the principle has remained hers: knowledge about a fungus becomes more reliable when a name can be referred to a safeguarded organism and its history.

Leadership of a programme does not erase its investigators

Utrecht University rightly credits Westerdijk with leading the Dutch elm disease programme, but an exact account should preserve the roles of her students. Bea Schwarz described the disease and isolated its associated fungus in 1922. Christine Buisman extended the infection experiments: external crown wilting could be reproduced when trees were inoculated between June and mid-August; outside that window the wood could show characteristic browning without leaf wilt. The group also examined the elm bark beetle as a vector. Westerdijk built the laboratory, living-culture collection and research programme in which these hypotheses could be tested, and supervised 56 doctorates, nearly half awarded to women. This is a story of scientific leadership and a research team, not a single “discovery by the first woman professor.” Naming Schwarz and Buisman strengthens rather than diminishes Westerdijk’s institutional achievement.