The ornate spade cleared a hole for a new tree as any other would, but the laborer just happened to be Prince Philip, husband of Queen Elizabeth II. And the tree that would take root in British soil just happened to be a hybrid elm from America. This simple act was part of a broader campaign to save the species from widespread annihilation.

Accompanying Prince Philip that day was Eugene Smalley, a professor of plant pathology at UW–Madison who had been tasked with fighting the spread of Dutch elm disease (DED) more than two decades earlier. First identified in the Netherlands in 1919, DED quickly spread through Europe via elm bark beetles before arriving in the United States in 1930. Since then, more than 50 million American elm trees have been felled. The towering Ulmus americana once stood as an elegant staple in communities across much of the United States.

“The American elm tree has had a unique niche in American life,” Smalley told The New York Times in 1989. “Before the disease, you could find streets lined with elms in almost every American town.”

Ray Guries, a professor emeritus in the Department of Forest and Wildlife Ecology and a former associate of Smalley’s, called the rapid decline of the American elm a “traumatic experience” for residents of urban areas. “When they disappeared, it was as though an icon had been lost.”

Early efforts to halt the spread of Dutch elm disease were ineffective. Smalley was hired in 1957 as part of a state initiative, and he immediately went to work planting elm seedlings at the Arlington Agricultural Research Station north of Madison. This stand became known as “Smalley’s Elms,” and many can still be seen today as one drives north- bound on State Highway 51.

Smalley theorized that hybrid species with natural pest resistance — not pesticides — offered the best defense against the beetles. Through 20 years of research, he and his colleagues produced several hybrids — Regal, American Liberty, New Horizon, and Cathedral — that proved to be hardy against the cold and generally resistant to DED.

Another promising hybrid was Sapporo Autumn Gold. When Prince Philip set one in the ground at Windsor Castle, he also planted the seeds of hope. That elm still stands today and has since propagated more than 100 others on the property.

Smalley died in 2002, but his legacy lives on. His disease-resistant elms have served as replacements all over the world. Even the embattled American elm may be bouncing back. Guries has spotted them being planted once again in Madison. Although it’s unlikely ever to reclaim its former status, the tree and its hybrid cousins serve as reminders that Smalley’s work will continue for decades.

“In developing the right tree, we don’t deal in years,” Smalley once told the Wisconsin State Journal. “We deal in generations.”