He was the founding president of the Donald Danforth Plant Science Center in St. Louis, Missouri, and the first director of the National Institute of Food and Agriculture.

He remained at Washington University, being promoted to associate and then full professor and becoming the head of the Center for Plant Science and Biotechnology, until 1991.

In 1999 he was recruited to be the inaugural president of the Donald Danforth Plant Science Center in St. Louis, MO as well as resuming his appointment was Washington University.

He left the Danforth Center in 2009 when he was appointed as the director of the National Institute of Food and Agriculture by President Obama, a role he served in until 2011.

His discovery of the CP-MR led to the development of virus-resistant varieties of potato, tomato, pepper, cucumber, squash, sugar beets, papaya and plum.