By Ross Korves 

Ten years after citrus greening was discovered in Florida in 2005, the citrus industry is ready to field test a potential solution.  The Environmental Protection Agency (EPA) has approved an Environmental Use Permit (EUP) application under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) for Southern Gardens Citrus (SGC) to conduct large scale tests of citrus plants with a protein derived from spinach that appears to help control the disease.  SGC President Rick Kress noted in a news release that a final solution to eliminating this disease may still take years.

The EPA website has the following general explanation about EUPs.  “EPA requires that a pesticide product undergo extensive chemical, toxicological, and field-testing before being registered as a pesticide.  Some testing is done under field conditions using commercial application equipment to fully understand the pesticide’s chemical properties, safety, and efficacy.  Because testing undertaken as part of the registration process necessarily involves an unregistered product or is for a use not previously approved in the registration of the pesticide, EPA sometimes must first authorize the distribution and sale under FIFRA section 5.  The EUP establishes limited conditions for the transportation, application, and disposal of the pesticide material used in the tests.  Pesticides registered under an EUP may not be sold or distributed other than through approved participants in the test program, and use is limited to the conditions specified in the EUP.  Biopesticides also require EUPs when used in experimental settings.”

Citrus greening was first detected in the early 1900s when it destroyed citrus trees in China, where it is known as huanglongbing (HLB), translated as yellow shoot disease, by choking off the flow of nutrients.  The disease is transmitted by the Asian citrus psyllid, first detected in Florida in 1998, an insect that sucks the bacteria out of one tree and injects them into another as it feeds on the sap of leaves.  The citrus industry in Florida tripled pesticide applications in an attempt to kill the insects to stop or slow the spread of the disease and feeds citrus trees additional micro- and macro-nutrients and resistance-enhancing products, but eradication is not now considered a feasible option.

According to a task force report from the National Research Council (NRC) released in 2010, a worldwide review of existing cultivated citrus found little or no evidence of immunity for any variety.  The lack of immunity in any cultivated variety eliminated traditional breeding to transfer immunity into commercial varieties.  With no hope of eradicating the disease or transferring immunity by traditional breeding, the future of commercial orange juice production in Florida was at risk.

That led SGC, one of the largest citrus producers in Florida, with three groves all infected with citrus greening, to seek solutions to the disease.  They participated in a wide variety of research projects with several universities and state and federal agencies focused on developing environmentally sound and scientifically proven methods to manage and control the disease.  Included was the research on the protein derived from spinach that attacks the invading bacteria, which was developed through a program with Texas A&M University Agri-Life Research and Erik Mirkov, a Professor of Plant Virology at Texas A&M University, Weslaco.  

SGC may now move forward with field tests, consistent with conditions set by EPA in the EUP, to evaluate the efficacy of the spinach protein against citrus greening in citrus plant tissues and continue to generate environmental, health and safety data that are required under federal law to support a fully registered product for commercial use.  On the basis of SGC’s related petition, EPA also has concluded that residues of the spinach protein in citrus are safe for the public.

Company President Kress said in the news release, “The company directed a research focus towards spinach because it is already safely consumed daily and should be more favorably received by consumers.”   Kress went on to say, “It is important to state that as all US regulatory controlled field trials and evaluations are on-going, there is no citrus fruit or juice product from the tests in the commercial product market today.”  As EPA said in its general explanation about EUPs, “Some testing is done under field conditions…”  Research theories and experiments will now be put to the test under real field conditions as allowed by the EUP from EPA.

While there is plenty of evidence from other crops about the safety of the technology, each crop is judged on the research information provided to EPA from field trials.  The oranges from these trees are expected to be the same as conventional oranges, but that will have to be shown by the results of the data collected for EPA.  Over 4.5 billion acres of biotech crops have been grown worldwide since the technology was commercialized in 1996.

If this research develops as expected, oranges will not be the first fruit that has benefited from biotechnology.   During the 1990s, papaya farmers in Hawaii almost lost the industry to the deadly ringspot virus that spread through the islands.  It became almost impossible to grow the fruit.  Papayas were made resistant to the virus by inserting a piece of the virus’s own genes into papayas, effectively inoculating plants.  The industry has recovered and 2,500 acres of biotech papayas are grown in Hawaii.  China has about 20,000 acres.   Other countries are developing resistant papayas for local markets.

Bananas may be next on the list of fruits threatened.  The popular Cavendish variety is threatened by the Fusarium wilt fungus that has been spreading around the world for the last 20 years.

As the field trials continue, the industry is looking ahead to consumer reactions.  Oranges and orange juice are widely traded globally.  Citrus greening also exists wherever oranges are grown.  What consumers decide will influence production and trade around the world.

Ross Korves is a Trade and Economic Policy Analyst with Truth About Trade & Technology ( Follow us: @TruthAboutTrade and @World_Farmers on Twitter | Truth About Trade & Technology on Facebook.


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