As a professor of nematology, he devoted years of study to, among other things, the role roundworms played in diseases of fruit and nut trees.

"His research was very thorough . . . (and) brought out results which ultimately were important to fruit and nut crop growers," said Dewey Raski, a retired professor who worked with Dr. Lownsbery.

Dr. Lownsbery was the author or co-author of more than 141 scientific publications and was editor in chief of the Journal of Nematology from 1978 until 1980.

Dr. Lownsbery came to UC Davis in 1953 as a lecturer and retired from the faculty as a full professor in 1983.

He taught an introductory course in nematology to undergraduates, but most of his time was spent working with graduate students and conducting research, according to his wife, Joyce Lownsbery.

He became interested in nematodes while he was a graduate student at Cornell University after World War II, his wife said. The potato fields of Long Island had become infested with a worm called the golden nematode, she said. Crops were being destroyed and the federal government funded the research effort.

"That's how he got started," his wife said. "That gave him money to do his research, money for his Ph.D."

Benjamin Ferris Lownsbery Jr. was born in Wilmington, Del., the only child of a mechanical engineer and a schoolteacher. After graduating from high school in Wilmington, he attended the University of Delaware. During World War II, he worked for DuPont making black powder for munitions. Shortly after the war ended, he enrolled at Cornell.

Immediately after earning his doctorate, he was hired as a nematologist by the U.S. Department of Agriculture in Beltville, Md. He then worked three years in New Haven, Conn., at the Connecticut agricultural experiment station.

At the Davis campus, he was known as a tenacious researcher who "was also a very pleasant person to work with," Raski said. "He took his share of extra work, committee work from the dean's office, whatever was needed. He was always willing to help."

In 1971, the American Society for Horticultural Science honored him for his work in developing worm-resistant peach trees. He belonged to the Audubon Society, the Sierra Club and the American Phytopathological Society.

Survivors include his wife of 47 years, the former Joyce Hagemeyer, who resides in Davis, and a daughter, Jill Lownsbery of Flagstaff, Ariz.