UC ANR Research at a Glance - Fighting to Protect California Citrus

UC Agriculture and Natural Resources is working with the citrus industry and the state to wage an all-out battle against the Asian citrus psyllid (the insect) and huanglongbing (the disease it spreads) that are threatening California’s citrus. This tiny insect and disease have already destroyed one-third of the citrus in Florida, at a cost of over $200 million a year, and both have recently been detected in California.

UC ANR is working to . . .

 

. . . educate communities about this serious threat to California’s citrus

UC Cooperative Extension is educating commercial growers and the general public throughout the state about Asian citrus psyllid (ACP). A free PowerPoint can be downloaded in English and Spanish, and an online educational webinar for growers, homeowners and landscapers is being developed. ANR  extension specialists are also training UC Master Gardeners to convey information about the pest and its management to the communities they serve.

. . . keep infected plants out of California

ANR scientists at UC Riverside are developing a legal source of popular, non-citrus plants that host ACP, such as bael tree and curry leaf, plants from India used in cuisine and traditional medicine. This program will provide clients with clean plants to reduce the incentive for smuggling plants and plant material into California that potentially harbor the insect and/or its disease.

. . . protect plants in nurseries

In Florida, ACP was not controlled, and it quickly spread on nursery shipments of citrus and orange jasmine that were planted in residential backyards. ANR scientists at UC Riverside are studying the efficacy of the systemic pesticide imidacloprid, which can protect young trees for up to three months.

. . . catch the insect and disease before it spreads

The geographical information systems team at the UC Kearney Agricultural Research and Extension Center in Parlier, in collaboration with the Citrus Research Board’s Citrus Pest and Disease Prevention Program, are developing a geographic database that will provide treatment coordinators with information to ensure quick action when the insect or disease is found.  

. . . build a better insect trap

ANR scientists at UC Riverside are testing olfactory neurons in the insect’s antennae to screen hundreds of chemicals as possible attractants and/or repellents. This could lead to better traps and/or repellents to protect citrus trees.

. . . introduce natural enemies to kill the insect

ANR researchers at UC Riverside are developing methods for mass rearing two insect natural enemies that theycollected from Pakistan. These two tiny wasps lay eggs inside bug nymphs; the hatching larvae eat the nymphs, killing them. Releases of one of the wasps are under way in urban areas of Southern California.

. . . detect the disease sooner

At UC Davis, ANR scientists are refining a mobile chemical sensor that can detect diseased citrus trees by sniffing their volatile organic compounds (VOCs). VOCs are emitted by all types of plants and contribute to their distinctive odors—such as the perfume of orange blossoms and pungent scent of garlic in the air.

Scientists at UC Riverside are working to identify the disease-induced molecules that will indicate whether a citrus tree is infected with the disease long before the plant expresses symptoms.

Meanwhile, other UC Riverside scientists believe that pathogen-specific proteins in a citrus plant’s phloem tissue could be a more reliable disease detection tool than the pathogen itself. The method was used successfully with citrus stubborn disease.

. . . develop methods to protect organic citrus

Scientists with UC Cooperative Extension are exploring treatment options for homeowners and farmers who do not use synthetic pesticides on their citrus. The current recommendation for organic growers is to spray a low rate of oil on trees at 14-day intervals. At Lindcove Research and Extension Center, the effects of this treatment on citrus health productivity and fruit quality are being evaluated.  A Cooperative Extension advisor is screening additional organic insecticides on a greenhouse colony of ACP to find products that may have greater persistence and efficacy against the insect.

. . . find cost-effective solutions for pest and disease management

UC scientists with the Agricultural Issues Center in Davis are developing economic models to estimate costs and the information necessary for a homeowner, grower or pest control adviser to determine the most effective and affordable ACP management for his or her situation.

. . . find long-term solutions to this deadly insect and disease

UC Ag Experiment Station scientists in Davis are using bioengineering to develop rootstocks that are resistant to HLB and other diseases, helping citrus evolve into a plant that is immune to the disease caused by ACP.

Meanwhile, researchers in Florida have found trifoliate orange rootstock to have some natural resistance to the disease. Now they are working with UC ANR scientists to transfer this resistance to edible citrus varieties.