WSU plant pathology graduates lead crop-defending clean plant programs across North America

Viral diseases cause multi-billion-dollar damages to global food crops annually. Scientists at Washington State University are training the next generation of virologists to fight these diseases with a simple but crucial tool: clean plants.

Growing crops from virus-tested seeds, tubers, or cuttings is one of the most effective ways to reduce the damage caused by plant viruses. Currently, six alumni of WSU's Department of Plant Pathology lead or manage clean-plant certification programs in five U.S. states and Canada, holding the first line of disease defense for apples, berries, sweet potatoes, ornamentals, and other important crops.

"There is no cure and no option to 'get rid of a virus' once a plant is infected," said Hanu Pappu, WSU professor and plant pathologist. "The best option is to avoid them in the first place. The often-repeated mantra is "start clean, stay clean."

The four doctoral graduates and two master's recipients - Christie Almeyda, Dan Villamor, Cristian Olaya, Dipak Poudyal, Segun Akinbade, and Noma Chingandu - are at the forefront of international efforts to protect the food supply.

Clean plants for Northwest crops

Now leading a statewide program providing clean planting stock to Washington's $2.4 billion apple, pear, and cherry industries, master's graduate Segun Akinbade came to the U.S. from Nigeria, where he developed a deep curiosity about viruses that damage staples like cassava, maize, rice, and plantains.

"The next step in my educational journey was to attend graduate school and engage in an original research project to try to find answers," Akinbade said.

Cristian Olaya, a 2019 doctoral graduate, began his career at the International Center for Tropical Agriculture in his home country of Colombia. Like Akinbade, work on a challenging cassava virus motivated him to continue his training.

"Dr. Pappu's lab was the right place to pursue my dream," said Olaya, who now coordinates Oregon State University's berry-focused Oregon Clean Plant Center. "My journey at WSU was a life-changing event."

Prepared to meet growers' needs

For the past 11 years, Dipak Poudyal, a 2012 doctoral graduate from adjunct Professor Xianming Chen's lab, has led Oregon's Plant Health Virus Certification Program, overseeing production of certified stocks of fruit trees, blueberries, and grapevines. Oregon is a major supplier of nursery stocks for specialty fruit crops, and in 2020 launched the nation's first blueberry nursery stock certification.

Poudyal's work with stakeholders at the state, regional, and national level has been crucial to meeting new challenges and providing reliable sources for growers in the U.S. and many other countries.

"Growing up in Nepal, I witnessed the devastating loss of farm income due to rice blast epidemics," he said. "This taught me a life lesson that cost-effective prevention is fundamental for food security and grower success."

Poudyal benefited from real-world case studies discussed in Pappu's graduate plant virology course, which help students understand how virus certification can be highly effective in managing economically significant viruses.

"The curriculum at WSU is comprehensive and prepared us to adapt to meet grower needs and ever-changing demands of our jobs," Poudyal said.

Dan Villamor, another 2012 PhD graduate, manages operations at the University of Arkansas System Division of Agriculture's Arkansas Clean Plant Center, a recently established, berry-focused member of the National Clean Plant Network. Originally from the Philippines, where he began his plant pathology career in the banana industry, Villamor joined WSU scientist Ken Eastwell's lab to study viral and virus-like diseases of stone and pome fruit crops.

After graduation, he helped integrate new rapid, computer-based DNA analysis at WSU Prosser's Clean Plant Center Northwest and worked on the emerging challenge of Little Cherry disease. When offered the job at Arkansas, Villamor knew it was a perfect fit thanks to years of experience at WSU.

Growing as scientists

A native of Zimbabwe, Noma Chingandu joined Pappu's lab in 2010 as a proud Fulbright Scholar.

"I had first-hand experience with the impact of diseases on food production and food security," she said.

Thanks to training and mentorship at WSU, Chingandu quickly gained a strong grasp on plant diseases, host-pathogen interactions, and diagnostics. Today, she is head of the grapevine program at the Canadian Food Inspection Agency's Centre for Plant Health, where she coordinates plant certification, contributes to research, and plays a key role in annual nationwide surveys at Canada's only post-entry quarantine and plant virology lab.

Christie Almeyda, a fellow 2012 doctoral graduate, sought out Pappu's lab after earning degrees in her home country of Peru as well as at the University of Minnesota. She now directs the North Carolina Clean Plant Center for sweet potatoes, berry crops, and muscadine grapes at North Carolina State University. The state is the largest producer of sweet potatoes in the U.S., supplying over half of the national crop.

More than 50% of North Carolina's annual sweet potato acreage is planted with stock derived from the Clean Plant Center, where Almeyda provides certified pathogen-tested material and manages production, research, funding, and diagnostics.

"I was given great flexibility and freedom to explore different research questions during my PhD," she said. "The ability to formulate new hypotheses and questions on your own is central to developing as an independent and productive scientist."