Roy James Thornton

Dr. Roy James Thornton died on March 4, 2026 in Vallejo, California at the age of 84 from complications arising from esophageal cancer treatment.

Roy was born in Bangor, Wales, UK, in 1941, to James and Eileen Thornton. He was raised in Rothbury and Thropton, Northumberland and attended The King Edward VI Grammar School in Morpeth. He went to college at Strathclyde University in Glasgow, Scotland, and remained there to complete a Ph.D. in Applied Microbiology in 1970.

The next year, Roy joined the faculty of Massey University in Palmerston North, New Zealand, where he would work for 20 years. In 1984, he met fellow microbiologist Dr. Susan Rodriguez at a conference in San Diego. The two soon formed a romantic and scientific collaboration that lasted the rest of his life. They were married in Napa, California in 1986, and welcomed the birth of their son, Mark, in 1988.

The three of them moved from New Zealand to the United States in 1991 to be closer to family. After several years in the Bay Area and Indiana, the family settled in Modesto, California in 1996, where Roy and Susan worked in the research division of E&J Gallo Winery. In 2001, they moved to Fresno, California, where Roy became a Professor in the Department of Viticulture and Enology at Fresno State. He retired in 2016 to Santa Rosa, California, but after their house burned in the Tubbs Fire the following year, Roy and Susan moved to American Canyon. There they cultivated a beautiful garden and traveled over the following decade.

Roy made a profound impact across half a century as a scientist and educator. He authored over 50 scholarly publications which advanced our scientific and practical understanding of yeast genetics and wine fermentation. He taught generations of winemakers in New Zealand and California, many of whom now work at the world’s top wineries, and who shaped the rise of household name brands like Kim Crawford and Michael David.

Roy was a lifelong sportsman, who played rugby, cricket, football (soccer), tennis, and golf. As a student, he led the Strathclyde Sports Union; as faculty at Massey, he coached college rugby, cricket, and football teams; and as a father, he coached his son’s youth soccer team. He was a devoted, though often disappointed, supporter of Newcastle United.

An avid lifelong reader, Roy went to bed almost every night with a book – or more recently, kindle – and an apple for good health. He particularly loved mysteries, like the work of Dick Francis, historical fiction, like Bernard Cornwell’s, and a wide range of science fiction.

Roy’s greatest joy was his family. He was a thoughtful, loving, and dedicated husband, son, and father. He and Susan were practically inseparable, collaborating as partners in the lab, home, and garden. Roy was a deeply engaged parent, who played a huge role in his son’s life and took great pride in his accomplishments.

Roy is survived by his wife, Susan, and his son, Mark, who miss him dearly. A private service will be held. In lieu of flowers, they welcome donations to the Northumberland Wildlife Trust’s efforts to conserve the Rothbury Estate near where Roy grew up: https://www.nwt.org.uk/what-we-do/projects/saving-rothbury-estate