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Elizabeth Grafton-Cardwell

Director, Lindcove Research & Extension Center
Elizabeth Grafton-Cardwell
Citrus Pest Management
Every year California’s diverse ecosystem is invaded by new, often-destructive species of exotic pests, resulting in annual economic losses of more than $3 billion. And, the central San Joaquin Valley is home to 75 percent of California’s commercial citrus. That’s where Professor Grafton-Cardwell is working to develop effective methods of keeping pest populations under control in order to minimize fruit damage so that growers can provide affordable, healthy fruit to consumers.

Areas of Expertise

Select Honors and Distinctions

  • California Citrus Industry, A.G. Salter Award (2008)
  • Entomological Society of America, Excellence in Pest Management (2006)
  • Citrus Research Board, Award of Excellence for Exceptional Service to the California Citrus Industry (2004)
  • Friends of Agricultural Extension Award for Outstanding Achievement (2003)
  • Entomological Society of America Pacific Branch Distinguished Achievement in Extension (2003)


Q: Why is your work important?
I study insect pests of citrus in the central San Joaquin Valley of California where 75 percent of the commercial citrus is grown. I develop integrated methods of pest control: I study the life cycles of pests and how to sample for them, I figure out how to preserve and boost their natural enemies, and I learn how to utilize pesticides in ways that minimizes their use. My work is important because it provides citrus growers with the most effective methods to keep pest populations under control and minimizes fruit damage so that growers can provide affordable, healthy fruit to consumers.

Q: What is the ultimate goal of your research? What challenges are left to achieve?
The ultimate goal of my research is to keep the citrus pests under control with as few pesticides as possible and to rapidly develop methods of identifying, monitoring and controlling new pests as they are introduced into California. The greatest challenge for me is that citrus integrated pest management is a dynamic system that I have to respond to with continually changing research and educational outreach programs. Factors that can dramatically change citrus pest management include new varieties of citrus, climate change, new pesticides and introduction of new pests from exotic places.

Q: What is the Asian Citrus Psyllid? Where has the insect been found?
The Asian citrus psyllid is a tiny, aphid-sized insect that arrived in Florida in 1998 and made its way into Southern California from Mexico during 2008. By itself, it is an irritating pest because the toxin it injects while feeding causes newly forming citrus leaves to curl and twist and break off. But of greater concern, is the fact that it is an efficient carrier of a bacterial disease called huanglongbing (HLB – sometimes known as citrus greening disease), and it is a death sentence for citrus trees. California citrus does not have the disease, it just has the psyllid, but the disease is found in Mexico and could easily come to California.

Q: Why should California growers be concerned about the Asian citrus psyllid? Who else should be concerned?
California citrus growers are very concerned, because the disease causes the leaves of the trees to yellow, the fruit to be oddly shaped and colored, and the juice to become bitter. Trees can die in as little as five years because the bacteria block nutrient flow to the leaves and fruit. HLB disease is causing widespread devastation of citrus trees in Florida and other areas of the world. There are more citrus trees in dooryards of consumers than in commercial citrus orchards, so California homeowners should also be very concerned about this disease killing their citrus trees.

Q: What is being done to stop the insect and disease?
A massive collaborative effort is underway involving the University of California, California Department of Food and Agriculture and the citrus industry that is designed to stop the insect from spreading northward and the disease from arriving in California. This effort includes surveys for the pest and disease, pesticide treatments where the psyllid is found, new regulations controlling fruit and plant movement, research to find a cure for the disease, and press releases and educational programs.

Q: If you had unlimited resources and no constraints, what would you do to further your research and extension program?
If I had unlimited resources and no constraints, I would mount a campaign to reach every homeowner and visitor in California with information about how dangerous it is to bring plants and fruits into California from outside the state because of the pests and diseases they might be carrying.

Q: What is it about UCR that makes this a great place to do your research?
UCR has stationed me at the Kearney Agricultural Center and the Lindcove Research and Extension Center where I am in the heart of the citrus producing area of California. These center locations help my research program to rapidly respond to grower needs and allow me to extend the information to the citrus growers in their own orchards.
Elizabeth Grafton-Cardwell“Citrus integrated pest management is a dynamic system. I have to respond by continually changing research and educational outreach programs.”

—Elizabeth Grafton-Cardwell
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