Briefing Report: Huanglongbing and the Asian Citrus Psyllid Threaten California’s Citrus Industry
The Huanglongbing (HLB) disease and its vector, the Asian citrus psyllid (ACP), are a direct threat to California’s $1.88 billion citrus industry.
The HLB and its vector have had a significant impact on citrus trees and subsequently citrus production around the world including Asia, India, China, South and Central America, Mexico and Florida. In Florida, where HLB was first detected in 2005, the disease has infected approximately 20 percent of all its citrus trees and costs approximately $300 million annually.
Otherwise known as the “citrus greening” disease or “yellow shoot” disease, HLB is one of the most destructive diseases of citrus trees worldwide. Once infected, the fruit becomes inedible and the tree must be destroyed to prevent the further spread of this disease. Currently, there is no cure.
The ACP, Diaphorina citri, is a small aphid-like bug that eats the leaves and stems of citrus and citrus-related trees and is destructive to citrus trees on its own. The psyllids are most likely found on new shoots, and the insect population increases during periods of active plant growth. Adult psyllids usually feed on the underside of leaves and can feed on either young or mature leaves. This allows adults to survive year-round. Once the psyllid picks up HLB, it carries it for the rest of its life. HLB is then spread by moving infected plant material such as potted plants, bud wood and leaves.
Thus far, the ACP, after first being detected in 2008, has been confined to urban areas in Southern California. Only one commercial citrus location has been affected. The United States Department of Agriculture’s Animal and Plant Health Inspection Service (USDA) and the California Department of Food and Agriculture’s Pest Exclusion Branch (CDFA) have confirmed populations of ACP in Los Angeles, Orange, Imperial, Riverside, San Diego and San Bernardino counties. These counties are currently under federal and state quarantines. The HLB has not yet been detected in California. However, there have been four detections of HLB in several different regions of Mexico between August and December 2009.
Invasive species are generally non-native plants, animals, microbes, diseases or plants that are capable of establishing populations in new areas, and the resulting uncontrolled propagation will likely cause economic or environmental harm.
Nationally, the economic impact of invasive species is estimated at $138 billion, which includes the costs of controlling and preventing the spread of invasive species, inspection of agricultural products entering and crossing borders, and the damage to crops and crop production.
In California, six new invasive species are introduced annually or approximately one every 60 days. Currently, invasive species cost the state’s agricultural industry approximately $3 billion annually.
Since 2008, the California Department of Food and Agriculture (CDFA), the lead agency in detecting, managing and eradicating harmful invasive species, has enacted emergency pest abatement and control measures for several infestations of invasive species including Asian citrus psyllid, European gypsy moth, Mediterranean fruit fly, Mexican fruit fly, Oriental fruit fly, Diaprepes root weevil and Sudden Oak Death.
Generally, there are two ways a non-native invasive species can be introduced into a foreign ecosystem, either through self-introduction or through human actions. Self-introduction of invasive species can occur as a result of high densities of species at a particular location that then get transported to another location via wind currents.
Human introductions of non-native species can be accidental or deliberate. Goods shipped from other states or countries via airplane, cargo ship, train and automobile or through the mail can contain insects or microorganisms that are unintentionally transported along with the goods to a new locale.
In the United States, the ACP was first detected in 1998 in Palm Beach County, Florida in backyard plantings of orange jasmine. By 2001, it had spread to 31 counties in Florida, with much of the spread due to movement of infested nursery plants. In the spring of 2001, ACP was accidentally introduced into the Rio Grande Valley on potted nursery stock from Florida. It was subsequently found in Hawaii in 2006 and in Alabama, Georgia, Louisiana, Mississippi and South Carolina in 2008.
In California, the ACP was first discovered on August 27, 2008, in San Diego County. In October 2008, it was found in Imperial County. Later, in August 2009, the ACP was found in Orange County. And then in August 2009, it was found in Los Angeles County. In late August 2009, over 100 psyllids were discovered in a FedEx package shipped to Sacramento.
California is one of the last citrus-producing regions in the world that has yet to be impacted, but HLB could invade California at any time. The risk is high. The most likely sources of a potential infestation would be from goods shipped to California from Florida, Mexico, Hawaii or Asia. The HLB may also find its way to California through self-introduction from Mexico.
Huanglongbing has the potential to have a significant economic impact on California’s citrus industry. The citrus industry generates nearly $1.88 billion annually and supports on average $3 billion in overall economic activity. The industry supports approximately 26,000 people in California and the industry’s productivity ranks second behind Florida.
According to the USDA’s Economic Research Service, California’s total citrus production has averaged 3.2 million tons per season over the past three seasons, about 24 percent of the nation’s total. California supplies approximately 80 percent of the nation’s fresh-market oranges, while Florida grows oranges mainly for juice. California also supplies 87 percent of the nation’s lemons.
Florida’s $9 billion citrus industry, which supports approximately 76,000 jobs, reports losses resulting from ACP and HLB at $300 million annually. To date, almost 60,000 acres of trees have been removed, which reflects approximately 10% of Florida’s commercial citrus production. Florida growers are spending on average $500 per acre annually on their ACP and HLB control and eradication efforts. One projection provides that almost all of Florida’s citrus trees will be infected in 7-12 years.
Moreover, a CDFA analysis projects that if the ACP begins to transmit the disease HLB, California’s entire citrus industry could be at risk. In one recent study in Florida, the presence of HLB increased citrus production costs by 40 percent. A CDFA analysis based on Florida’s experience suggests that it could cost $224 million or approximately 20 percent of California production.
What is Being Done?
To date, California’s citrus industry has been working with federal, state and local officials to detect, quarantine and eradicate ACP and to prevent the introduction of the citrus greening disease.
In particular, since the ACP and HLB are a national problem, the departments of agricultures of other citrus-producing states have been working with the USDA to develop a comprehensive plan to detect quarantine and eradicate ACP.
The plan requires, in relevant part, increased inspections at points of entry such as international ports, state lines, airports and mail-sorting facilities; education programs; quarantining affected states; the development of new traps and controls; and the development of resistant varieties of citrus.
Recognizing the effects of HLB on Florida’s citrus production, and the devastating impact it has had on other citrus-producing regions, the USDA is expending federal funds to fight the spread of HLB in Mexico to California.
In California, CDFA’s Pest Eradication Branch leads the state’s efforts to detect and eradicate the ACP. CDFA’s funding for its detection and trapping activities is, in part, being underwritten by the USDA. Under federal law, these federal funds cannot be used for the state’s eradication efforts. CDFA’s eradication efforts are currently being funded by its own agency appropriations. CDFA’s pest eradication funds, however, are not unlimited.
The citrus industry is taking a proactive stance in its fight against the ACP. Last year, AB 281 (De Leon) Chapter 426, Statutes of 2009, established the Citrus Pest and Disease Prevention Committee and an industry-funded program to assist in combating citrus specific diseases, vectors, and pests when found in California. CDFA estimates the industry-supported fee assessments will total $1.7 million to combat the introduction of ACP.
The devastating impact on Florida’s citrus industry, coupled with the long-term nature of the problem, illustrate the importance of being proactive and aggressive in preventing both the spread of ACP and the introduction of HLB in California’s thriving citrus industry. Legislative efforts should focus on ensuring that CDFA and other relevant agencies have the resources and funding necessary to protect this vital industry.
For more information on this report or other Food and Agriculture issues, contact Scott Chavez, Senate Republican Office of Policy at 916/651-1501.