Johanna Westerdijk was the first female professor in the Netherlands. In 1917, Westerdijk was appointed Professor of Phytopathology at Utrecht University at the age of 34. This appointment resurrected Phytopathology as a field of science within plant biology. Westerdijk was a popular and inspiring teacher among students. She supervised 56 PhD candidates, and therefore played an important role in Phytopathology at Utrecht University. In 1930, she was also assigned as Professor by special appointment at the University of Amsterdam.