فول
On his return to the University of Constance he made a habilitation at the Department of Mathematics and Natural Sciences, with a thesis entitled: "The Role of Haustoria in the Biotrophic Interaction of the Rust Fungus Uromyces fabae and its Host Plant Vicia faba". There followed the award of the venia legend for Phytopathology and Microbiology, and appointment to the academic board.