Born in Minneapolis, Minnesota in 1917, Oswald did his undergraduate work in botany at DePauw University, Greencastle, Indiana and received his Ph.D. from the University of California in 1942.
During World War II, Oswald served as a PT boat captain in the Mediterranean.
In 1946, Oswald taught plant pathology as an assistant professor at the Davis Campus of the University of California.
He was chairman plant pathology department at the Berkeley Campus in 1954.
In 1962 he became vice president for administration in the statewide system for the University of California.