• PD/GWSS Board News

Leading Pierce’s Disease Researcher Set to Retire

Sacramento, Calif, May 11, 2006 – One of the world leaders in Pierce’s disease (PD) research, Dr. Alexander (Sandy) Purcell, will be retiring this June from U.C. Berkeley after 35 years of research on the disease.

Over the years when not in the lab or classroom, Dr. Purcell could often be found in a vineyard somewhere in the world. His smile and youthful, almost contagious, enthusiasm for his research projects highlight that even after 35 years he is still just as interested and curious about his research as when he began.

“Since before our statewide program began, Sandy has been one of California’s leading experts on Pierce’s disease,” said PD Control Program Statewide Coordinator Bob Wynn. “His value to this program extends well beyond the walls of his lab; he has also been a tremendous resource for his fellow scientists as they pursue parallel paths toward a solution.”

Dr. Purcell’s introduction to PD began while studying at U.C. Davis when he received a fellowship provided by Napa growers to conduct research on a grape virus called Pierce’s disease. “In those days PD was believed to be a virus,” explains Purcell.

“I studied plant pathology under Dr. George Nyland at U.C. Davis,” adds Purcell. “He had been conducting some heat therapy studies on virus diseases. Heat treatments that should not have worked on viruses cured the cuttings, which could then be planted. He and a colleague thought that if PD was a virus, that shouldn’t have worked. So they started looking for a mycoplasma as the possible cause, but only found bacteria with an electron microscope . At first they thought it was a bacterium that fed on decaying tissue of the diseased vines, but we saw it so consistently that it was proposed as the possible cause of PD. By then I switched my studies from virology to bacteriology in my graduate work.”

Thus began Purcell’s first studies into Pierce’s disease. “In my research, I found that vines could recover from PD. When my advisor told me that vines couldn’t recover, I thought I had done something wrong. It turns out I was right, and I was able to prove it.” -more-

After graduating from U.C. Davis, Purcell became an assistant professor in U. C. Berkeley’s Department of Entomological Sciences. His research efforts have centered on insects as vectors of bacteria and phytoplasmas that cause plant diseases and symbiosis of bacteria with plant sap-feeding insects.

Over the years at U.C. Berkeley, Purcell has risen through the ranks, starting in 1972 as an assistant professor and rising to become the chair of the entire department from 1993 to 1994.

Ed Weber, U.C. Cooperative Extension Farm Advisor, Napa, Calif., has been involved with Purcell on countless projects since 1988. “I’ve worked with Sandy over the years to help him identify vineyards in the Napa region for his graduate students to use for research,” reports Weber. “I also worked directly with him over three or four years on the severe pruning project that we conducted. What has always struck me about Sandy is that from entomology to microbiology he uses a multitude of scientific disciplines that all relate to PD.”

“Sandy recognized very early just how critical an issue PD was for our industry,” said Dana Merrill, a San Luis Obispo winegrape grower and a member of the PD/GWSS Board. “He has been a real advocate to plead the growers’ case to other researchers and to help define what the threat was. And while no silver bullet has yet been discovered, Sandy has developed many practices that we growers can use to lower our risk of getting PD. The industry owes him a big debt of gratitude.”

“For 35 years, Sandy has been the standard-bearer for PD,” says Kim Waddell, Executive Director of the American Vineyard Foundation, who worked with Purcell during the National Science Foundation’s Pierce’s Disease Research Priorities study. “Over the years he tried to answer many questions about PD, and he did it with little or no resources for much of that time.”

Although Purcell will be leaving U.C. Berkeley, he hasn’t finished with PD research yet. “I plan to do some independent research,” says Purcell. “I’d like to look into some symbiotic bacteria relationships, and I have some long-shot ideas I’d like to explore.”

“He’ll be missed in the PD research community,” concludes Waddell. “His legacy to the grape industry and the PD research community is that today we are asking smarter questions and traveling down fewer dead-ends thanks, in large part, to his body of work.”


The PD/GWSS Board was established in July 2001 to support scientific research to find a cure for Pierce’s disease. An annual assessment paid by winegrape growers supports its research efforts. The PD/GWSS Board also advises the California Department of Food and Agriculture on a variety of other issues pertaining to Pierce’s disease and the glassy-winged sharpshooter.

The work of the Board is underlined by the fact that Pierce’s disease has no known cure and, left unchecked, could be devastating to the grape industry and several other California crops. A study recently released by the Wine Institute and the California Association of Winegrape Growers showed that the total annual economic impact of California’s winegrape industry is estimated at $45.4 billion.

California Department of Food and Agricu