All citrus trees within a five-mile radius of a Los Angeles neighborhood are under quarantine this week after a tree infected with a deadly citrus disease was found in a suburban backyard.
The citrus blight is referred to under multiple names — including citrus greening, Huanglongbing (HLB) or yellow dragon disease — and is one of the most serious diseases affecting citrus plants. It is a bacterial disease spread by two invasive Asian insects. While it is not dangerous to humans, it attacks trees' vascular systems, first causing the trees to produce bitter, misshapen, inedible fruit and eventually killing the infected trees.
According to the U.S. Department of Agriculture (USDA), the two insects that carry this citrus blight arrived in Florida in 1998 and 2005. The University of Florida estimates the disease has cost more than 6,600 jobs, $1.3 billion in revenue to growers and $3.6 billion in economic activity since 2005.
California officials have been warning about the possible arrival of HLB since the Asian citrus psyllid, one of the insects that spreads the HLB bacteria, was first found in the state in 2008. The disease, which has a two-year latency period, was finally detected March 30 on a lemon-grapefruit hybrid tree in a Hacienda Heights neighborhood. According to the California Department of Food and Agriculture (CFDA), "this area is part of a much larger quarantine already in place" following sightings of the Asian citrus psyllid. The quarantine prohibits the movement of all tree nursery stock out of the area. Only commercially cleaned and packed citrus may leave the area or the property on which it is picked.
"The success of any quarantine depends on cooperation from those affected," CDFA Secretary Karen Ross said in a prepared statement. "The stakes couldn’t be higher for California citrus. We urge residents in the Hacienda Heights-area to do all they can to comply."
The CFDA says the quarantine on the neighborhood will last for at least two years. At some point this week, the CDFA and the USDA will begin to treat all citrus trees for psyllids within 800 meters of the site of the infected tree. Trees within a half-mile of the infection site will be tested for the disease. The infected tree itself will be destroyed.
According to the website Californiacitrusthreat.org, HLB can infect all kinds of citrus trees, including oranges, lemons, tangerines, limes, grapefruit and kumquats, as well as plants closely related to citrus. The website offers information on what to look for when inspecting trees, both for signs of the Asian citrus psyllid and for infected trees.
The California citrus industry generates about $2 billion annually. The state citrus industry has been preparing for the worst, contributing $15 million a year to state and federal programs to stop the spread of the invasive insects and HLB disease. "This is the other shoe dropping," Ted Batkin of the California Citrus Research Board told the Associated Press. "We're prepared, and now we'll put our game face on."