Professor Quanjer studied pharmacology in Amsterdam. After working as an assistant at the Phytopathological Laboratory, ‘Willie Commelin Scholten’, under Professor Ritzema Bos, Quanjer joined Ritzema Bos at the Rijks Hoogere Land-, Tuin- en Boschbouwschool (National Higher College of Agriculture, Horticulture and Forestry) in Wageningen in 1906.

Quanjer’s accurate anatomical observations of diseased potato plants led him to discover phloem necrosis (elm yellows). This discovery formed the start of his many virus studies, which were highly influential for Dutch potato cultivation.

In 1918, Quanjer was appointed professor of the newly founded Agricultural College.