Key Takeaways:
- The California Department of Food and Agriculture (CDFA) is spotlighting biocontrol efforts during Invasive Plant Pest and Disease Awareness Month (IPPDAM) in April.
- CDFA’s Citrus Pest and Disease Prevention Division has released more than 34 million Tamarixia radiata wasps across California since 2012 to combat the Asian citrus psyllid (ACP).
- ACP spreads Huanglongbing (HLB), an incurable citrus disease detected in Los Angeles, Orange, San Bernardino, San Diego, Riverside, and Ventura Counties.
- Strict quarantine zones are in place across affected regions, prohibiting the movement of homegrown citrus plants, clippings, or fruit in or out of those areas.
- Residents are urged to inspect backyard citrus trees regularly, control ants near trees, and report suspicious symptoms to CDFA’s pest hotline at 1-800-491-1899.
CDFA Marks IPPDAM with Focus on Biological Pest Control
In recognition of Invasive Plant Pest and Disease Awareness Month this April, the California Department of Food and Agriculture (CDFA) is drawing attention to its ongoing efforts to protect California’s agricultural and residential landscapes from invasive pests and diseases — including its use of biological control methods.
Tiny Wasps Serve as a Natural Defense Against ACP
Central to CDFA’s biocontrol strategy is Tamarixia radiata, a small, stingless parasitic wasp used to suppress populations of the Asian citrus psyllid (ACP). ACP is the invasive pest responsible for spreading Huanglongbing (HLB), a deadly and incurable citrus plant disease.
Tamarixia wasps feed on ACP nymphs, preventing the pest from reaching maturity and reproducing. The wasps pose no threat to humans or pets.
CDFA’s Biocontrol Program: More Than a Decade of Releases
CDFA’s Citrus Pest and Disease Prevention Division (CPDPD) launched its biocontrol program in 2012 in collaboration with the University of California, Riverside. Originally concentrated on residential citrus trees in Southern California — where ACP first established — the program has since expanded statewide.
To date, CPDPD has released more than 34 million Tamarixia across California. The division now leads all aspects of Tamarixia rearing and release, working alongside partners that include UC Riverside, California Polytechnic State University Pomona, the United States Department of Agriculture, and Canine Detection Services.
CDFA Biocontrol Extends Beyond Citrus
Biological control is not limited to the fight against ACP. CDFA employs additional biocontrol strategies across other programs, including sterile insect releases to address fruit fly infestations and the use of natural enemies within the Pierce’s Disease Control Program.
Quarantine Zones in Place Across Six Counties
HLB-infected citrus trees have been detected in Los Angeles, Orange, San Bernardino, San Diego, Riverside, and Ventura Counties. Quarantine zones are currently active across these regions. Residents within quarantine areas are prohibited from moving homegrown citrus plants, clippings, or fruit into or out of those zones.
CDFA Calls on Residents to Take Protective Action
During IPPDAM, CDFA is encouraging residents statewide — particularly those in quarantine regions — to take proactive steps to protect their citrus trees. ACP, which measures only one-eighth of an inch in length, feeds on citrus leaves and stems and can transmit HLB as it moves between trees. Once a tree is infected, it will die.
Steps Residents Can Take
CDFA recommends the following precautions:
- Control ants near citrus trees. Ants disrupt Tamarixia‘s ability to parasitize ACP. Residents should apply safe ant control products around the base of citrus trees and throughout the yard. The University of California Agriculture and Natural Resources offers guidance on appropriate options.
- Inspect backyard citrus regularly. Residents should look for signs of ACP or HLB, including yellow shoots, mottled leaves, or misshapen fruit, and report unusual symptoms to CDFA’s pest hotline at 1-800-491-1899.
- Support agricultural crews. Cooperating with agricultural officials conducting monitoring or treatment activities helps accelerate early detection of ACP and HLB.
- Dispose of plant material safely. Citrus clippings should be dried or double-bagged before being removed from the property to prevent ACP from spreading via plant debris.
