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USDA offers $30 million to fight citrus diseaseUSDA offers $30 million to fight citrus disease

Citrus growers say the biggest challenge remains the threat caused by Asian citrus psyllids (ACP) and the spread of dreaded Huanglongbing (HLB) disease.

Logan Hawkes

March 3, 2015

6 Min Read

For Deep South Texas, the citrus season will soon slowly grind to an end, and while some Rio Grande Valley citrus growers are reporting slightly lower production numbers compared to 2013, most say they welcomed recent rains that may have slowed harvest a little but also helped some produce larger fruit this season.

While the jury is still out on whether the year goes down as good or bad for citrus production in South Texas, most growers say the biggest challenge remains the threat caused by Asian citrus psyllids (ACP) and the spread of dreaded Huanglongbing (HLB) disease.

HLB, better known as citrus greening disease, was first confirmed in the Rio Grande Valley in 2012, the first confirmed incident of the disease in Texas. Citrus greening, first identified in 2005 in Florida orchards, destroyed hundreds of thousands of acres of citrus there before spreading to other states including Georgia, South Carolina and Louisiana, Texas and other states, most recently to California and Arizona.

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Citrus plants affected by citrus greening may not show symptoms for some time. On average, latency persists for approximately 2 years. As the pathogen moves within the tree, whole branches and eventually the entire tree may progressively turn yellow and will die. While the fruit is not infected with the disease and the disease has never been a threat for human consumption, every tree that becomes infected must be replaced as there is no known cure for the deadly pathogen.

Virtually all of the Texas Valley is currently under quarantine by USDA. Fruit produced in the Valley can ship out of the area, but it must be free of stems and leaves. The quarantine, however, does limit the movement of citrus nursery stock outside of the quarantined area.

Ongoing research

To avoid heavy crop losses like those experienced in Florida, USDA has been researching the disease and the psyllid that carries it for several years. Additional funds for that research were made available in the latest farm bill. While millions were dedicated to the project late last year, a new round of funding has just become available.

Agriculture Secretary Tom Vilsack announced earlier this month that $30 million in funding is available for 22 new projects that will help citrus producers combat HLB.

Vilsack says the money will fund "promising projects that could offer near-term solutions" as well as research funding that may develop long-term solutions. The promising near-term tools and solutions are funded through the HLB Multiagency Coordination Group; the research projects are funded through the Specialty Crop Research Initiative Citrus Disease Research and Education (CDRE) program, available through the Agricultural Act of 2014.

"Our HLB Multi-Agency Coordination Group has worked closely with the citrus industry to select and fund projects that we think will make a real difference for growers against HLB," said Vilsack. "Funding these projects through cooperative agreements puts us one step closer to putting real tools to fight this disease into the hands of citrus growers. Through the CDRE research, we are also investing in long-term solutions to diseases that threaten the long-term survival of the citrus industry."

Fifteen projects

USDA's HLB Multi-Agency Coordination Group funded fifteen projects that support thermotherapy, best management practices, early detection, and pest control efforts for a total of more than $7 million. All of them are designed to provide near-term tools and solutions to help the citrus industry fight HLB. The projects include:

  • Two projects to provide improved delivery of thermotherapy to HLB infected trees, a promising treatment that has been shown to help infected trees regain productivity after treatment. One of these projects will test thermotherapy on a grove-wide scale.

  • Six projects to provide citrus producers with best management practices in Florida citrus groves.

  • One project will focus on lowering the pH of the irrigation water and soil to strengthen the root systems of citrus trees to help them better tolerate HLB infection.

  • Three projects will support different combinations of integrated management approaches for sustaining production in trees in different stages of infection.

  • Two projects will test strategies for preventing tree death due to HLB infection. One of those will field test rootstocks that have shown ability to tolerate HLB infection. The other will use technologies to rapidly propagate the tolerant material for field use by the industry.

Three projects to increase early detection of HLB:

  • One project will train dogs to detect HLB infected trees. Detector dogs have proven to be highly adept at detecting citrus canker and early results suggest they will be an effective early detection tool for HLB.

  • One project will develop a root sampling and testing strategy.

  • One project will compare several promising early detection tests.

Four projects to provide tools to kill the Asian citrus psyllid (ACP), the vector of HLB:

  • One will produce and release the insect Diaphorencyrtus aligarhensis as a second biological control agent in California.

  • One project will use a bio-control fungus to kill ACP adults.

  • One project will use a trap to attract and kill ACP adults.

  • One project will increase the use of field cages for the production of the insect Tamarixia radiata in residential areas, especially those that are adjacent to commercial groves in Texas. Tamarixia has already proven to be an effective biological control agent for ACP. Using field cages will enable the wider use of this effective ACP control.

More funding for research

In addition to these projects, USDA's National Institute of Food and Agriculture funded more than $23 million dollars for research and education projects to find lasting solutions to citrus greening disease. Examples of funded projects include developing HLB-resistant citrus cultivars, the development of field detection system for HLB, using heat as a treatment for prolonging productivity in infected citrus trees, creating a new antimicrobial treatment, among others. A fact sheet with a complete list of awardees and project descriptions (PDF, 316KB) is available on the USDA website. Fiscal year 2014 grants have been awarded to:

  • University of California, Davis, Calif., $4,579,067

  • University of California, Riverside, Calif., $1,683,429

  • University of Florida, Gainesville, Fla., $4,613,838

  • University of Florida, Gainesville, Fla., $3,495,832

  • University of Florida, Gainesville, Fla., $3,338,248

  • University of Florida, Gainesville, Fla., $2,096,540

  • Kansas State University, Manhattan, Kan., $3,734,480

CDRE is a supplement to the Specialty Crop Research Initiative (SCRI). The focus of this year's funding was specifically on citrus greening disease. USDA reports that because there are wide differences in the occurrence and progression of HLB among the states, there were regional as well as national priorities for CDRE.

These priorities, recommended by the Citrus Disease Subcommittee, fall within four categories: 1) priorities that deal with the pathogen; 2) those that deal with the insect vector; 3) those that deal with citrus orchard production systems; and 4) those that deal with non-agricultural citrus tree owners.

About the Author(s)

Logan Hawkes

Contributing Writer, Lost Planet

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