Joseph Sieczka, professor emeritus of horticulture, an expert on potatoes, died July 29 at his home in Mattituck, New York. He was 79.

He also worked as a Cooperative Extension agent in western New York and served as coordinator of Cornell’s Long Island Horticultural Research and Extension Center in Riverhead, New York, for more than two decades.

Though he conducted research on vegetable crops, he focused on potatoes. Over the course of his career, he managed widely acclaimed potato extension programs, and his work on potato cultivation led to reduced grower costs and lower nitrate impacts on groundwater. Sieczka’s applied potato research included strategies for weed control and determining optimal applications of fertilizer. And he helped develop new potato varieties, including some that are resistant to golden nematodes, a major potato pest.

“Joe was extremely knowledgeable in all things ‘potato’ and had an encyclopedic memory,” said Donald Halseth, professor emeritus of horticulture. “He knew things about more potato varieties than anyone I have known.”

“From a personal point of view, I always valued the uncommon amount of ‘common sense’ that Joe showed when I would ask for his advice, which I did very often,” said Elmer Ewing, professor emeritus of horticulture. “He had sound judgment on important issues and was able to see the broad picture.”

Hailing from Blaisdell, New York, outside Buffalo, Sieczka received an associate degree in agronomy and soil conservation from the State University of New York at Alfred in 1960, a bachelor’s degree in agronomy from the University of Georgia in 1963 and a master’s in vegetable crops from Cornell in 1973.

In 1964, he began work as an extension agent in Steuben County, New York. He joined Cornell’s faculty as an extension specialist in 1968 and became an associate professor in 1981. At Cornell, he ran a research program on horticultural aspects of potato production. In 1980, he became coordinator of the Long Island Horticultural Research and Extension Center, where he stayed until he retired in 2001.

“Joe Sieczka was such a noted expert on potatoes and other vegetable crops that it earned him tremendous respect from the entire agriculture community,” said Mark Bridgen, professor in the School of Integrative Plant Science and director of the Long Island Horticultural Research and Extension Center.

Sieczka was elected an honorary life member of the Potato Association of America, where he served in many capacities, including president. He was co-author of two editions of the association’s handbook, Commercial Potato Production in North America.

Sieczka was also a co-author of “The Complete Book of Potatoes: What Every Grower and Gardener Needs to know.”

He is survived by three children.