During his career at the University of California, Davis, he primarily researched diseases that affected crops like lettuce, tomatoes, and beans.
[1] Grogan served in the Navy during World War II and was enlisted for three years.
[1] After his military service, he enrolled at the University of Wisconsin–Madison and completed a PhD under advisor John Charles Walker, researching diseases of cultivated beans.
He also discovered the transmission route of the bacteria Pseudomonas tomato, how to prevent halo blight of beans, and the cause of corky root rot in lettuce.
[5] Grogan was elected as a fellow of the American Phytopathological Society in 1969; in 1987 he received its Award of Distinction.