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Tri-national citrus disease plan being finalized

(Media-Newswire.com) - McALLEN, Tex. -- A cooperative agreement among the U.S., Mexico and Belize to protect their commercial citrus industries from an incurable plant disease is expected to be signed within days, according to experts who met recently at a conference in McAllen.

The conference, hosted in part by Texas AgriLife Research and the Texas AgriLife Extension Service, drew stakeholders from various countries concerned about the disease that is harmless to humans but devastating to citrus production regions of the world, including Florida.

“I suspect that other countries will join the effort as they become infected with citrus greening,” said Ray Prewett, president of Texas Citrus Mutual in Mission.

Citrus greening, also called Huanglongbing, is a bacterial disease that keeps fruit from maturing ( thus the name greening ) and eventually kills the tree.

The plan calls for the detection, delimination, treatment and quarantine of citrus greening and the insect that spreads it -- the Asian citrus psyllid -- to protect the citrus production areas of each country, Prewett said.

“All three countries have the disease in one place or another,” Prewett said. “But they also have the commitment and support of their respective citrus industries and governments to implement this plan as soon as possible.”

The tri-national agreement is in its final stages of editing, Prewett said.

“Funding sources have been identified and all three countries are ready to proceed with the plan,” he said.

Dr. John da Graca, director of the Texas A&M-Kingsville Citrus Center at Weslaco, said the consequences of citrus greening are disastrous.

“Many immature fruit fall off infected trees, while remaining fruit are lopsided, remain partially green and taste bitter,” he said. “Symptoms spread throughout the tree which slowly declines and can eventually die.”

The disease was first reported in a scientific paper in India in 1927 but may have been present since the 18th century, he said.

“It spread by movement of infected plants throughout south and southeast Asia during the 20th century, was confirmed in Brazil in 2004 and in Florida in 2005.”

The disease has been devastating for the Florida citrus industry, where more than one million trees have been removed as part of the effort to control it, da Graca said. It has since been found in dooryard trees in Louisiana, Georgia and South Carolina. Prevalent also in Cuba, it has recently been found in Belize and the Yucatan state in Mexico.

“The Texas citrus industry in South Texas is now seriously threatened by this disease,” Prewett said. “In fact, we’re encircled by it. Florida has had it for some time, it’s been detected in Louisiana and it’s widespread in the Yucatan Peninsula of Mexico.”

While the disease has not yet been detected in Texas, there are plenty of psyllids around to spread the disease.

“Needless to say, we are very supportive of these international efforts and there’s a lot of work to be done here,” he said, “but experts agree that in a place like South Texas where the psyllid is endemic, the populations can’t be eradicated. It’s never been done anywhere in the world.”

Buying time, Prewett said, is an important ingredient in the plan’s efforts.

“The idea is to suppress the populations of psyllids in order to buy time for researchers to come up with scientific solutions to this very debilitating citrus disease,” Prewett said. “The lower the psyllid populations in a recently infected area, the slower the spread of the disease.”

“Once a tree is infected, there is no cure. There is no treatment,” Prewett said. “Once a tree is infected, it must be destroyed to prevent it from being an inoculate for the further spread of the disease.”

Representatives of Mexico and Belize expressed optimism in the plan’s objectives.

Dr. Javier Trujillo, director general of plant health in Mexico, said citrus greening would be an issue for at least another 20 years and that his country was ready to sign the agreement.

“I’m happy we have a plan,” he said. “The three countries can now move forward at the same pace to combat this problem. I’m satisfied that we’re now at a point that once we proceed with this plan, we’ll be as successful as we have been in our 30-year effort against the Mediterranean fruit fly.”

Mexico, with over one million acres of commercial citrus production, has been successful in pushing medfly populations south of their border.

Immediate needs against greening include a better disease detection system and a better public outreach effort to discourage the movement of plant material, Trujillo said.

Francisco Gutierrez, director of plant health with the Belizean Agricultural Health Authority, said Belize had recently hired a coordinator for their national citrus greening program, as well as six technicians and several scouts who were surveying orchards and dooryard, or patio, trees.

"The citrus industry is facing devastation if we don’t do anything,” he said. “The challenge will be to maintain the human, financial and material resources. We have the commitment to the plan from our Minister of Agriculture and our industry has established a box tax on itself to fund some of the efforts.”

Dr. Stephen Williams, director of the Citrus Research and Education Institute and the representative of the Belizean Citrus Growers Association, said Belize has a citrus industry of 45,000 acres, most of which are Valencia oranges.

“Citrus is an important agricultural commodity in Belize,” he said. “The majority of our fruit is used for processing for concentrate to blend because our citrus has a reputation for strong color. It is sent to the U.S., the Caribbean and Europe.”

After surveying trees for several years, citrus greening was detected in Belize in May, Williams said. Since then nine more samples have tested positive.

The tri-national group of about 40 representatives who met at the conference in McAllen last week broke after agreeing their next step should be to identify working group leaders. Those leaders, they decided, will report to the group at their next meeting in Merida, Mexico, next summer.

The tri-national group discussion was moderated by Dr. Osama E-Lissy, director of emergency programs with the U.S. Department of Agriculture’s Animal Plant Health Inspection Service and the Plant Protection and Quarantine.

Other conference hosts included Frito-Lay Inc., Texas A&M-Kingsville Citrus Center and Texas Citrus Mutual.