What you don't now about Easter lilies
by Kathy Keatley Garvey
April 17, 2014
• The science behind them
• Without which they’d be dead, deader and deadest
Becky Westerdahl checks out Easter lilies with Lee Riddle, director of the Easter Lily Research Foundation
(Photo by Zeke Harms)
The Easter lilies that grace homes and churches this time of year probably wouldn't be there — or be as pretty -- without scientists like nematologist Becky Brown Westerdahl of the University of California, Davis, and the methods she uses to battle nematodes.
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,” says Lee Riddle, director of the Easter Lily Research Foundation in Brookings, Ore. “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.”
Ms. 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.
A Cooperative Extension nematologist and professor based in the UC Davis Department of Entomology and Nematology, Ms. Westerdahl 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,” Mr. Riddle says. “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, Ore., and the Smith River area of northwest Del Norte County, Calif., 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,” Mr. Riddle says, “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.
Ms. Westerdahl has worked closely with the Easter lily industry for some two decades. “Each year Becky puts out 120 plots of bulbs,” Mr. Riddle says. “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.”
Ms. Westerdahl has found as many as 7,500nematodes per gram of root in the past.
She 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,” says Mr. Riddle. “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.”
The growers use ozone generators pumping ozone under the lilies, various combinations of plant-oils-that-smell-good-enough-to-eat as bulb soaks, 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 Ms. Westerdahl “tested quite a number of beneficial organisms,” which Mr. Riddle describes 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,” Mr. Riddle says, “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 Ms. Westerdahl scrambling.
She says the lesion nematode 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 notes.
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,” Ms. Westerdahl says. The California Department of Food and Agriculture awarded them with a Specialty Crop Block Grant for Sustainable Easter Lily Production.
(About the writer: Kathy Keatley Garvey is a writer for the
UC Davis Department of Entomology and Nematology)