Della A. Whittaker, 46, a retired technical editor and writer at the Army's Harry Diamond Laboratories who also had worked at the Department of Agriculture and taught at the University of Maryland, died of cancer Jan. 12 at her home in Adelphi.

Mrs. Whittaker was born in Philadelphia and reared in Washington. She earned bachelor's and master's degrees at the University of Maryland. In 1972, she received a doctorate in English teaching at Maryland.

During her years as a graduate student, she taught at Maryland. She also taught at Prince George's Community College.

In the early 1970s, Mrs. Whittaker was a technical editor in the Agricultural Research Service at the Agriculture Department. She joined the Harry Diamond Laboratories in 1977 and retired there in 1982.

Mrs. Whittaker was active in the International Technical Communication Conference of the Society for Technical Communication. She was a member of the National Council of Teachers of English, the Toastmaster's International chapter at the Harry Diamond Labs, and the Beltsville Garden Club.

She also was a member of the Unitarian Church of Rockville and the Paint Branch Unitarian Church in Adelphi. As a volunteer with the American Cancer Society, she had counseled other cancer patients.

Survivors include her husband, Denis Whittaker of Adelphi; two sons, Capt. Paul E., of Seaside, Calif., and Jeff, of Adelphi; and a granddaughter.