Kay Ryugo

Profile photo of Kay Ryugo

In Memoriam
Professor Emeritus of Pomology
1920-2016

KAY RYUGO

Birth: April 10, 1920, Sacramento, California
Death: June 13, 2016, Boise, Idaho

Education

  • B.S., Horticulture, University of California, Davis, 1949
  • M.S., Horticulture, University of California, Davis, 1950
  • Ph.D., Plant Physiology, University of California, Davis, 1954

Military Service

  • First Sergeant, 100th Infantry Battalion, 442nd Regimental Combat Team, U.S. Army, World War II
  • Service: 1942–1945
  • Decorations: Army Good Conduct Medal, American Campaign Medal, World War II Victory Medal

Employment

  • Agricultural Experiment Station Assistant Researcher, Department of Pomology, UC Davis, 1955–1978
  • Professor and Pomologist, Agricultural Experiment Station, UC Davis, 1978–1988
  • Professor Emeritus, Department of Pomology, UC Davis, 1988–2016

Honors, Awards, and Professional Societies

  • Travel Fellowships and Lectureships in Italy, Greece, Japan, and China
  • Honored by the Japanese Horticultural Society for research accomplishments and mentorship

Research Contributions and Impact

Kay Ryugo’s research spanned physiological, biochemical, and developmental changes in fruit and nut trees, including peach, nectarine, pear, Asian pear, persimmon, cherry, almond, prune, kiwifruit, walnut, pistachio, and chestnut. He contributed to solving pomological challenges such as pear decline, fire blight, and pistillate flower abortion.

He played a pivotal role in advancing high-density plantings in walnut orchards and collaborated on the development of mechanical hedging systems. These innovations improved orchard efficiency, reduced costs, and supported the adoption of new high-yield walnut cultivars. His field-oriented research and close ties with Cooperative Extension transformed California walnut production and sustained higher yields.

Publications and Scholarly Leadership

Ryugo authored Fruit Culture: Its Science and Art (1988), based on his long-standing pomology course at UC Davis. He also published widely on fruit tree physiology, flowering, and orchard management, providing both scientific insights and practical guidance.

Teaching and Mentorship

For two decades, Ryugo taught a core pomology course on fruiting of tree crops, where students valued his practical expertise in grafting, budding, and pruning. He supervised M.S. and Ph.D. students in Horticulture and Agronomy and Plant Physiology graduate groups. In later years, he continued to assist with teaching and annually maintained his kiwifruit collection for demonstration and research purposes.

Collaboration and Community

Ryugo collaborated extensively with international colleagues in Japan, Italy, Greece, Chile, and China. His strong connections with UC farm advisors and Cooperative Extension specialists made him a trusted mentor and resource for California growers.

Legacy

Kay Ryugo is remembered as a scientist, teacher, and mentor who advanced the understanding of fruit tree physiology and helped reshape walnut orchard management in California. His textbook, teaching, and field-based research left an enduring mark on pomology. Outside of academia, he was an accomplished woodworker and ceramicist, crafting furniture, art, and violins.

References

For additional tributes, interviews, and biographies, see the following resources: