He transferred to the Agricultural Division of Monsanto in 1967, motivated by the department's "emphasis on publishing, academic contacts, and the freedom to pursue ideas.
"[5] Because his background was in organic chemistry, Franz familiarized himself with the new field by spending a year studying and learning about plant physiology and biochemistry before beginning research.
Over the course of his career, Franz published over forty papers and wrote the book Glyphosate: A Unique Global Herbicide with Michael K. Mao and James A. Sikorski.
[citation needed] Researchers at Monsanto had been searching for an herbicide that was effective against annual and perennial weeds for nine years but found little success.
In 2007, when he was inducted into the National Inventor's Hall of Fame, Franz said, "It's a recognition of the entire team of scientists who worked on and supported the development of Roundup herbicides".
This breakthrough spurred Monsanto to design and produce plants genetically immune to glyphosates in order to make it easier for farmers to thoroughly spray down their fields for weeds without killing their own crops.
German Chancellor Angela Merkel stated in June 2019 that “we will come to a point where glyphosate isn’t used anymore.”[10] Bayer, which acquired Monsanto, stopped selling Roundup for residential use in 2023[11] "exclusively to manage litigation risk and not because of any safety concerns".
In 1990, he was awarded the Perkin Medal by the American Section of the Society of Chemical Industry, based on his contributions to the research and development of applied chemistry.
On December 8, 1995, the agricultural company introduced the Franz Sustainability Award, which consists of an annual $100,000 prize given to the individual or team that submits the best environmental project for improvement in the areas of conservation, technology, and/or education.