Joseph O. Culbertson, 74, an Agriculture Department scientist who did research on flax and sugar beets, died April 29 of heart disease at Holy Cross Hospital in Silver Spring.

Mr. Culbertson, who held a doctorate in agronomy from the University of Minnesota, worked for the Agriculture Department for 37 years. From 1952 until he retired in 1968, he was president of the Flax Institute, and in 1974, a new variety of rust-resistant flax seed was named Culbert flax in his honor.

Born on a farm in Dakota City, Neb., Mr. Culbertson earned bachelor's and master's degrees at the University of Nebraska. He started work for the Agriculture Department in 1931 as a sugar beet investigator in Salt Lake City.

In 1936, he was transferred to St. Paul, Minn., where he earned a doctorate in 1940, and then became a professor of agronomy at the University of Minnesota in 1948.

Mr. Culbertson came to the Agriculture Department's Research Center in Beltsville in 1957, and was assistant chief of its oil seed and industrial crops research branch.

He was a member of the American Society of Agronomy and the Crop Science Society of America.

Surviving are his wife, Belle, of the home in Silver Spring, to whom he had been married 50 years; a son, Ward also of home, and a sister, Alice Lewis, of St. Louis, Mo.