- Author: Kathy Keatley Garvey
Nematodes, also known as “round worms,” can kill Easter lilies. And they do.
“Easter lilies have no natural resistance to nematodes and all attempts to breed in resistance have failed,” said Lee Riddle, director of the Easter Lily Research Foundation in Brookings, southern Oregon. “Without both soil treatment and in furrow root treatment at planting, Easter lilies will die from nematode infestation, I mean dead foliage, dead stem, dead roots, dead bulb, end of story, dead plant.”
Westerdahl's research involves the interactive management of plant parasitic nematodes that feed within the plant's roots. Sometimes the “glop” she uses on the agricultural crop resembles the contents of a kitchen sink drain or something composting in an unkempt refrigerator, say her grateful colleagues.
Westerdahl, a Cooperative Extension nematologist and professor based in the UC Davis Department of Entomology and Nematology, works closely with UC Cooperative Extension Farm Advisors, growers and the industry to protect agricultural crops, including Easter lilies.
“Our unique little microclimate on the north coast of California, and south coast of Oregon is the only place in North America where Easter lilies can be grown,” Riddle said. “It gets too hot or too cold everywhere else. There is only a thin strip of land between the ocean and the coast range of mountains of perhaps 2,000 acres where this crop can be grown.”
The two-county area straddling Brookings, located in southwest Curry County, Oregon, and the Smith River area of northwest Del Norte County, California, is known as the “Easter Lily Capital of the World.” Misted by the Pacific Ocean, the coastal strip is where growers cultivate 95 percent of the world's Easter lily bulbs. That amounts to some 11 million bulbs annually.
“Every field on this bench of land has been used repeatedly since the 1940s to produce this crop,” Riddle said, “so every square inch of this land has been infested with nematodes from at least the early 1950s. Easter lilies are in the soil up to 13 months between planting and digging, so control measures must last at least a year or the lilies will die.”
Westerdahl has worked closely with the Easter lily industry for some two decades. “Each year Becky puts out 120 plots of bulbs,” Riddle said. “Our crop is pretty unique in that it takes three full years to grow a mature-sized marketable bulb. We field-plant and harvest bulbs in the fall of each year, a process that takes August, September, and October to complete. We redig every bulb every year to move them to a newly treated field because the nematode pressure is so high. We also treat as we replant due to the nematode pressure.”
Riddle said that “some of Becky's earlier work looked at alternative cover crops that might reduce nematode populations in the soil. We routinely ‘rest' each field for three years between lily crops with a grass-plus-clover cover crop. This regenerates the high organic matter that lily crops require but it also grows nematodes. At one point, Becky kept some soil plots absolutely bare of vegetation for four years hoping to starve them out, but they were still there after four years.”
Westerdahl travels to the research foundation station at least four times a year: in early September to harvest the previous year's trial; in mid-October to plant the next year's trial; around Easter to present trial results to the growers; and in late June for the foundation's annual field tour where she showcases the test plots.
October's heavy rains can prove problematic. “We watch the forecasts but often we end up in the shed watching 3-inch rains drenching our planting area,” Riddle said. “Over the years Becky has tried everything but the kitchen sink, although that is not exactly true because some of the things probably came out of the kitchen sink. I remember her coming up one year with bags full of petri dishes full of some glop which she spooned into a blender. Then she mashed that through a kitchen strainer and glopped that on top of the planted bulbs.”
“We have had ozone generators pumping ozone under the lilies, various combinations of plant-oils-that-smell-good-enough-to-eat as bulb soaks, we've cooked bulbs in hot water, smothered them in crab shells, watered them with electronically altered water, and dosed them with an alphabet soup of numbered compounds.”
Recently Westerdahl “tested quite a number of beneficial organisms,” which Riddle described as resembling “something you might find in the hidden corners of an unkempt refrigerator.”
“I guess you could honestly say that Becky has thrown the kitchen sink at Easter lily bulb nematodes,” Riddle said, “and we hope she continues to give our nematodes some grief.”
Prior to 1941, Japan produced and marketed most of the world's Easter lilies (Lilium longifloru), which are native to Japan's southern islands. When World War II eliminated America's dependence on Japanese-produced bulbs, commercial bulb production shifted to the United States, in the small stretch of southern Oregon/northern California area where the mild climate, ocean mist, protective bay, rich soil and abundant rainfall proved perfect for growing superior bulb crops. Japan has never regained the market.
Nematodes, however, keep the growers, industry and Westerdahl scrambling.
Westerdahl says the lesion nematode (Pratylenchus penetrans) can “devastate the Oriental and Easter lilies.” The multiple-year growing cycle for these crops requires a high degree of control for both the planting stock and the soil, she noted.
In collaboration with Humboldt County Farm Advisor Deborah Giraud, “our research has resulted in a greater understanding of the biology of the nematode, plus innovations in crop rotation, pre-plant treatments of bulbs, and biological methods for pre and post-plant treatment of soil,” Westerdahl said. The California Department of Food and Agriculture awarded them with a Specialty Crop Block Grant for Sustainable Easter Lily Production.
"Becky has always been willing to do research in my far away location," Giraud said. "She truly believes in supporting Advisors in the counties and helping solve grower's problems in their fields with the campus lab work to verify results. I have thoroughly enjoyed working with her and appreciate her dedication to Extension.
A native of Riverside, Westerdahl joined the UC Davis Department of Nematology (now Entomology and Nematology) in 1986. Her position as a statewide nematologist encompasses 85 percent Cooperative Extension (UC ANR) and 15 percent I & R.
How did she become interested in nematology? “I have to blame it on the Boy Scouts,” Westerdahl said. My father (former Riverside Mayor Ab Brown) was a troop leader and he knew two faculty members at UC Riverside, also involved in Boy Scouts. I had just graduated (1972) from Chapman College in southern California and was looking for a summer job. My father got me a job with Seymour D. Van Gundy counting nematodes. After counting nematodes under a microscope all day, I continued to see and count them in my dreams at night. After I did that, I knew I never wanted to do it again.”
She went on to receive her doctorate in biology and nematology from UC Riverside in 1978.
Westerdahl's position involves teaching, research and public service. She's taught an online course for 12 years; teaches a graduate course every other spring, and teaches general biology every spring. Her research deals with new developments in nematode biology and management. But mostly she's out in the field. “I'm pretty much a field person,” she said.
“I like to work with newer advisors to help them get started,” she said. When she receives calls from growers asking how to control nematodes, she first wants to make sure that they're nematodes. “If they say they see them crawling around in the soil, I know they're not nematodes because they're microscopic.”
“There are no statewide solutions. There are individual growers working with individual solutions. I find out what their needs are; what their problems are.”
Westerdahl, highly honored by the Society of Nematologists with its CIBA Recognition Award for Excellence, also works on other commodities, including tomatoes and turf grass. In addition, she provides expertise on plant parasites of sugar beets, carrots, cantaloupes, broccoli, peppers and strawberries.
Westerdahl came to UC Davis as a postdoctoral scholar of apiculturist/bee scientist Norm Gary and medical entomologist Robert Washino. Her interest in bees and beekeeping led to her being elected the first secretary-treasurer of the 500-member Western Apicultural Society, formed at UC Davis.
“When I had an opportunity to recruit her as a postdoc in my lab, I jumped at the chance at a time my lab was expanding our efforts on biological control agents on mosquitoes that showed promise,” said Washino, now an emeritus professor, former chair of the department, and a former special assistant to the dean of the College of Agricultural and Environmental Sciences.
“At that time, I knew she was a cum laude graduate of Chapman College in southern California and was working with Ed Platzer's nematology lab on the parasitic nematode, Romanomermis culicivorax, a worthy candidate against mosquitoes breeding in permanent-semi permanent aquatic habitats.”
Soon Westerdahl was elected president of the worldwide 600-member Society for Vector Ecology (SOVE) that “was rapidly becoming a popular national organization for medical entomologists,” Washino said. “ Becky finally agreed to join our lab primarily as a laboratory worker, but quickly adjusted her experimental activities to conduct both field and laboratory studies. She was the senior author of several papers from my lab. My deep respect for her professional as well as personal conduct continues to this day.”
Westerdahl developed and maintains a website on Nematode Knowledge Expectations for Pest Control Advisors (PCAs).
Her research spans chemical and cultural practices, as well as multidisciplinary approaches involving weeds, fungi, nematodes, fumigant dispersal and fumigants. She also manages nematodes with insecticides and fungicides and has helped to register new nematicide active ingredients.
In addition to short-term projects, Westerdahl engages in longer term high high-risk projects involving nematode biology and diagnosis. “This approach has historically received little attention because of its high risk for failure, and system pressures to rapidly generate publications,” she said. “Inclement weather preventing sampling or applications, early termination of perennial crops by growers, and destruction of buried data loggers by cultivation equipment are examples of setbacks we have experienced in this research.”
Today the young college graduate who vowed never to count nematodes again after working at a summer job, does that and more. “Becky has been involved in all of my research on methyl bromide alternatives,” said Cooperative Extension specialist Husein Ajwa, based in Salinas. “Becky has been my go-to nematologist since day one, evaluating nematodes in my research plots, answering questions or reviewing my proposals and papers. Without her help, my work would have lacked the crucial knowledge on the efficacy of soil fumigants. In short, Becky's desire to study nematodes has overshadowed even my desire to fumigate them.”
Westerdahl, known in the department for her savvy technology in our increasingly advanced digital world—she's never met a computer, scanner, printer or cell phone she can't master and she jokes that “I'm Amazon's biggest customer”--has seen rapid changes in other areas as well. “I used to tally 30,000 miles on my car every year for Extension work, but now I do more flying than driving.” In addition, the love of traveling extends to her personal life. She and her retired husband, Dane, enjoy traveling to foreign countries--but she probably has nematodes on her mind, at least part of the time.
“It's an honor to be a nematologist,” Westerdahl said, “and to work and solve problems.”
Related Links:
Easter Lily History: Easter Lily Research Foundation
The Life of an Easter Lily: Easter Lily Research Foundation
Gallery of Easter Lily Photos: Easter Lily Research Foundation
