Thung resumed his studies in Wageningen in 1924. In 1919, the Rijks Hoogere Land-, Tuin- en Boschbouwschool had been transformed into the Agricultural College, with modified and extended examination requirements. Thung enrolled in the study programme in Agricultural Engineering. This period defined Thung’s scientific career, not least because of the lectures he followed with Professor Quanjer. In 1924, Thung completed an internship in the test fields and greenhouses of the Laboratory of Mycology and Potato Research, where he took his first steps as a phytopathologist. Quanjer continued to play an important role throughout Thung’s scientific career, and the two remained friends throughout their lives.