Plagues,
Pestilences and Diseases
Deadly Citrus disease discovered in California fruit
Threat to state's $2B citrus market
The Associated Press
Posted: Mar 30, 2012 7:29 PM ET
Last Updated: Mar 30, 2012 10:40 PM ET
Citrus affected by 'greening,' an insect-borne bacterial disease,
is shown in a laboratory at the U.S. Department of Agriculture's
U.S. Horticultural Research Laboratory in Fort Pierce, Fla., in
September 2010. Citrus affected by 'greening,' an insect-borne
bacterial disease, is shown in a laboratory at the U.S. Department
of Agriculture's U.S. Horticultural Research Laboratory in Fort
Pierce, Fla., in September 2010.
A deadly citrus disease that has killed millions of citrus trees
and cost growers billions of dollars across Florida and Brazil has
been detected in California, despite the industry's best efforts
to keep it at bay.
After a week of testing the U.S. Department of Agriculture
confirmed at noon Friday that citrus greening was detected in a
lemon-grapefruit hybrid tree in a residential neighbourhood of Los
Angeles County.
The disease stands to threaten not only California's nearly $2
billion US citrus industry, but treasured backyard trees scattered
throughout the state.
"Huanlongbing is called the world's worst disease of citrus," said
Dr. Robert Leavitt of the California Department of Food and
Agriculture. "It had been present until now in all of the world's
major citrus producing areas — except California."
The bacterial disease, also known as huanglongbing, is carried by
the Asian citrus psyllid and attacks a tree's vascular system,
producing bitter fruit and eventually killing the tree.
Sap-sucking psyllids that feed on an infected tree become carriers
of the disease.
It is not a threat to humans.
"It's disappointing," said Joel Nelson of California Citrus
Mutual. "Now we'll see if this great program that we believe we
have in place is going to work."
Detection of the disease has been state citrus growers' fear since
the bug first crossed into San Diego County from Mexico in 2008,
potentially threatening California's fresh citrus market. Despite
25 years of worldwide research, there still are no biological or
genetic controls for the disease that keeps fruit from ripening.
The disease is present in Mexico and across the southern U.S., but
nowhere is the problem more severe than in Florida, where the
disease first appeared in 2005. The University of Florida
estimates it has cost 6,600 jobs, $1.3 billion in lost revenue to
growers and $3.6 billion in lost economic activity.
The pest and the disease also are present in Texas, Louisiana,
Georgia and South Carolina. The states of Arizona, Mississippi and
Alabama have detected the pest but not the disease.
California growers and state agricultural officials have been
aggressively trapping and testing bugs for the disease since the
first sighting four years ago.
"This is the other shoe dropping," said Ted Batkin of the
California Citrus Research Board. "We're prepared, and now we'll
put our game face on."
The industry group will ramp up trapping efforts and increase
testing samples in an effort to keep the disease from crossing
into the San Joaquin Valley, where 80 percent of the state's
citrus grows. California growers have been contributing $15
million a year to fund efforts to fight both the psyllids and the
disease on top of state and federal programs to fight its spread.
"We've been fortunate that we have been able to learn from the
experiences of other citrus-growing areas of the world," Leavitt
said. "They didn't know they had the psyllid or the disease until
it was too late. We have learned from their scientists and have
taken a proactive approach."
State officials are making arrangements to remove and dispose of
the Los Angeles County tree, which so far is the only one found to
be infected. They also will spray all citrus trees for psyllids
within a half-mile of the infected tree. Testing on tissue samples
from other trees within the half-mile radius is ongoing.
As of Saturday all sales and shipments of citrus trees within a
5-mile radius of the infected site will be suspended. State
officials also are working on a larger quarantine that will extend
into northern Orange County. The closest commercial grove is 14
miles away.
State officials are unsure why Los Angeles County has a higher
rate of psyllid infestations than areas closer to the Mexican
border. But officials are investigating whether the bugs are
hitchhiking through airports and seaports.