As the US government and research institutes bank on antibiotic sprays and future GMOs to save dying citrus groves, Frank Dean says a simple solution is available – but few are listening. Report by Claire Robinson

Citrus greening disease has devastated millions of acres of citrus crops throughout the United States and elsewhere. In an effort to combat the disease, the Environmental Protection Agency (EPA) proposes to expand the mass spraying of the antibiotic streptomycin as a pesticide on citrus groves. The EPA has already approved the use of another antibiotic, oxytetracycline, for this purpose.

Both streptomycin and oxytetracycline are used to treat human and animal diseases. The obvious concern is that mass spraying of these antibiotics on citrus groves will add to the already serious problem of antibiotic resistance in people and farm animals, as well as affecting wildlife.

Meanwhile some US universities, including the University of Florida (UF), are attempting to develop genetically modified (GMO) disease-resistant trees. They are backed by a chorus of pro-GMO lobbyists, who have been claiming for years that GM will provide a solution to citrus greening. The University of Illinois at Urbana-Champaign put out a press release headed, “Future of US citrus may hinge on consumer acceptance of genetically modified food”. Yet no GM citrus greening-resistant tree looks set to appear on the market any time soon.

In addition, a GM virus designed to protect the trees by delivering bacteria-killing spinach proteins is in the US regulatory pipeline. Whether it will work in the field is unproven.

Simpler solution available?

Frank Dean, product development manager at Performance Nutrition®, a division of the company LidoChem, Inc., says that in his opinion, these approaches miss the point. He has developed what he sees as a simpler, safer, and more publicly acceptable cure for the disease. He also says it has been proven to work. It doesn’t involve antibiotic sprays, GMOs, or any significant cost to the grower. Yet it seems that the solution is being ignored by the US government and the universities alike.

Why? In Dean's opinion, the reason could be that his solution appears to raise suspicion that Bayer/Monsanto’s widely used yet controversial glyphosate herbicide is a culprit in the disease.

What is citrus greening disease?

The definition of citrus greening disease is contentious in itself. The disease is generally assumed to be caused by a bacterium called Candidatus Liberibacter asiaticus, which is thought to be spread by an insect called the Asian citrus psyllid. Trees that succumb to the disease produce fruits that are green, misshapen, and bitter. They’re unsuitable for sale as fresh fruit or for juice. Most affected trees die within a few years.

But Frank Dean is not convinced that the bacterium is the cause of citrus greening. He believes that the disease is actually a metabolic and nutritional problem in plants caused in part by the overuse of pesticides, especially glyphosate herbicides, which are used in non-organic citrus orchards to kill weeds and grass around trees.

Citrus Greening Recovery Program

Performance Nutrition’s® approach to citrus greening is called the Citrus Greening Recovery Program. The program focuses on restoring soils, alongside building the trees’ innate resistance systems and providing them with the nutrition and organic substances they need to regain their health. An important element is cleaning the soil of residual glyphosate and helping growers to reduce or eliminate glyphosate applications.

One Florida grower who successfully implemented the program but wishes to remain anonymous had lost his groves to citrus greening. When the disease decimated his last 50 acres, the grower told his sons they were “done with being in the citrus business”. However, a chance meeting with a Performance Nutrition® manager led to his gaining renewed inspiration. He bought a new grove and used it to trial the Citrus Greening Recovery Program.

The move was a success. “I couldn’t be doing what I’m doing without the products from Performance Nutrition®,” said the grower. He added that the company “understands the biology side of it. Looking at the whole soil aspect of it – soil and tree fertility, dual-chelated minerals, and diverse populations of microbes. The living part of the soil is feeding the tree so the plant is healthy and bears fruit. Healthy soil makes healthy trees.”

The program has also gained the support of Dr Roger Webb, a former University of Florida plant pathologist and the CEO of Tree Tech Microinjection Systems. Dr Webb has accompanied Dean on visits to the citrus groves where the program has been implemented and is convinced that it works.

Interview with Frank Dean and Dr Webb

Frank Dean and Dr Roger Webb answered GMWatch’s questions in the following interview.

GMW: How did the citrus greening problem start and how widespread is it?

FD: Citrus greening has been a problem in Florida for more than ten years, with some researchers claiming they noticed symptoms as far back as 1995. The majority of citrus groves are afflicted with it, with all tree varieties experiencing problems to varying degrees. Our work on citrus greening has been done in Florida.

GMW: How did you come to work out your approach to citrus greening?

FD: As I studied citrus greening, I noted that the pathology was similar to diseases that had afflicted crops in the Midwest. Corn, soybeans, and tomatoes suddenly developed unexpected problems (for instance, tomatoes would not turn red), resulting in crop losses.

As a company, we address all aspects of growing healthy and productive crops: soil composition and characteristics, microbial activity, nutritional needs, and supplying the organic compounds needed for a properly functioning defence system. Our approach was successful in the Midwest so I went about customizing a program to grow healthy citrus.

I found that the over-use of glyphosate was a contributing factor in the case of the crops listed above, so I suspected it was also a contributing factor in citrus greening.

The problem has been made worse by the replacement of overhead irrigation systems by micro irrigation, where water is fed directly into the root zone from lines laid along the ground. The idea is to save water by reducing evaporation, but micro irrigation means that growers cannot mow the weeds and grass, as mowing would damage the irrigation lines. Herbicide then becomes essential to control the weeds and grass. Glyphosate is applied and this causes the leaves on the trees to turn yellow. It is well known that the Asian citrus psyllid is attracted to yellow leaves.

However, I don’t see insects, bacteria, fungi, and plant diseases as causes of the disease. Viewed holistically, they are “nature’s garbage collectors”. They are an indication that something is wrong with the system – either it’s nutrient-deficient, or there’s a metabolic disorder. In my opinion, this also explains why insecticide applications haven't worked in combatting citrus greening – the psyllid insect is a symptom and not the cause.

This knowledge led me to the hypothesis that disease symptoms are caused primarily by increasing frequency and rate of pesticide applications, and the accumulation of pesticide residues in soil. In my opinion, pesticides suppress the plant’s production of compounds that are critical to its health and defence systems. The metabolism of the plant’s cells is suppressed, causing a build-up of toxic substances in the organism, or a deficiency of substances needed for normal function, either of which can lead to serious symptoms.

Further, in my opinion, pesticides cause changes in the soil microbial ecosystem. I think years of unrestricted pesticide applications have led to a tipping point for some crops, such as tomatoes and citrus.

GMW: Describe the elements of your Citrus Greening Recovery Program.

FD: Our program comprises:

* Remediation and biodegradation of residual glyphosate in the soil through the use of a patented organic soil inoculant

* Restoration of soil microbial diversity and populations

* Replenishment of micronutrients and organic compounds known to be blocked by glyphosate

* A change in cultural practices, enabling growers to manage their weeds with lower concentrations of glyphosate and fewer applications.

GMW: Please describe the results.

FD: Thus far we have had success. We only work on abandoned acres with years of no production or harvest. Our work has focused on a 20-acre plot of Valencia orange trees, which has been highly successful. Trees identified by UF extension agents as “dead or dying”, that were almost barren of leaves and new shoots and had not had a harvest for three years prior to our treatment, now have full canopies of leaves, an abundance of fruit, and have generated their third harvest. These approximately 3,000 trees no longer show significant symptoms of citrus greening.

In rDNA tests, they scored 34.4, above the threshold of 32, meaning the DNA for the pathogen was no longer present.  

On a more recent trial in Vero Beach, the restoration to health is beginning to show. New leaves and shoots are appearing on branches that appeared dead, the leaves are properly shaped and sized, and the trees are now producing buds. As with our Valencia orange trial, these grapefruit trees had not produced fruit for three years.

GMW: Why do you think it works?

FD: We have enabled the trees’ defence systems to perform properly. Without a compromised defence system, they are able to fight off the infection on their own and be productive again.

RW: One of the products used in the program is NutriSmart®,* which consists of specially chosen yeast. It was developed to supply nitrogen, phosphorus and potassium through microbial action and to degrade organophosphate compounds, of which glyphosate is one. Glyphosate blocks shikimate, the end product of the shikimic acid cycle, which is responsible for the production of the three aromatic amino acids that are essential for plant growth and health: tryptophan, tyrosine and phenylalanine. Tryptophan is converted to a plant hormone that helps the tree make strong roots, and phenylalanine and tyrosine are natural plant antibiotics that protect the tree from diseases and parasites.

The problem with glyphosate is that it blocks these essential amino acids from being produced in the plant. It also selects for and reduces beneficial soil bacteria – and reduces the availability of nutrient minerals to the plant. The result is a perfect storm of conditions that predispose the plant to falling sick.

The NutriSmart® product works by breaking the carbon-phosphorus bond in glyphosate, ending its herbicidal effect and allowing the affected plants to recover to productivity. The Citrus Greening Recovery Program also involves several applications of the three vital aromatic amino acids to replace those lost from glyphosate applications, along with selected nutrients that may be lacking, such as molybdenum and nickel.

GMW: What about the antibiotic spraying program that is being rolled out? Will it work?

FD: Our tests with antibiotics have not been successful. About five years ago I formulated an oxytetracycline injection for Dr Webb at his Tree Tech company. There was no visible response to the injections on plants that had symptoms of citrus greening. Later, I worked with Dr Webb on formulating a combination of antibiotics for injecting citrus trees. Again, this didn’t work.  

RW: In my opinion, antibiotic sprays do not address the root causes but only target the supposed cause, the “candidate” bacterium. The bacterium is the presumed cause of citrus greening. But in order to prove that any given bacterium causes any given disease, criteria known as Koch’s Postulates have to be met. In the case of this bacterium and citrus greening, they have never been met. The organism has even resisted attempts to grow it in culture – the second Postulate.

As a plant pathologist, I view it as a sin to call something that has never met the conditions of Koch's Postulates a genuine pathogen. But microbiologists can label something under investigation for pathogenicity as a “candidate”, which is why “Candidatus” is placed in front of its name. Note that the “candidate” part is frequently (although in my opinion not accurately) omitted.

Since this "disease" was “detected” in Florida in 2005, it has been found everywhere. From then on, the money flowed like water to programs targeting the supposed bacterium. In my opinion, some persons profiting from the flow of funds from the government have been motivated to avoid questioning whether the bacterium actually exists.

GMW: If the bacterium isn’t the cause of citrus greening, it seems clear that the antibiotic approach will not work. What about the other “solution” that is constantly promoted – GM trees?

FD: Is GMO really a solution that is in the best interest of the grower? It would be years before these trees would produce fruit, the growers would no longer own their trees, and there is no guarantee they won’t succumb to another pathogen if their cultural practices don’t change. And young consumers do not want GMO crops or foods.

RW: I find the trend of talking about GMO-only techniques to find a "cure" ominous. In my opinion, there is not enough time nor funds to find a "cure" for established groves, especially in Florida. Therefore Florida citrus will continue to decline if current cultural practices are maintained. You only have to take a drive through what remains of citrus production in Central Florida to see this slow but progressive devastation in progress.

There is a push for GMO-based programs that focus on blaming insects and non-pathogenic bacteria for the disaster, while not disclosing what in my opinion is the real goal of such programs: imparting glyphosate tolerance to the GMO trees. How else will citrus saplings be able to thrive if they are planted back into soil heavily contaminated with glyphosate and AMPA [a degradation product of glyphosate] residues from the previous citrus crop?

Frank's work to rehabilitate citrus greening-affected Valencia oranges was successful and these results were presented at the 2018 American Society for Horticultural Science annual meeting. The trial showed a statistically significant difference between treated and therefore recovering trees, as opposed to untreated trees, which continued to decline. However, I haven't found a single federal or state reference to his work – which did not entail any government funding. Apparently, it is GMO for the future but no solutions for the present crisis. It’s pitiful.

In my opinion, simple prudent cultural practices such as those developed by Frank are being not just discredited but deliberately overlooked in order to foster research aimed at gaining control of genetic resources for future manipulation.

In 2013 the UF announced it was closing its Southwest Florida Research and Education Center at Immokalee due to financial shortcomings. In my opinion, the real story was that a group of faculty members there were not giving up their contention that citrus greening was actually a reversible nutrient-related disorder instead of a disease caused by the purported bacterial pathogen – which has never been proven to be pathogenic.

Ten days later, after a grower uproar and an understanding that faculty were not to work on nutrient issues but rather devote their efforts to the still unproven “pathogen”, the closure was called off. A team from the UF came to Immokalee to announce renewed support for the Center. They told the growers that attended the meeting that Monsanto and UF were joining forces in an effort to develop GMO citrus lines that were resistant to the bacterial (as yet unproven) pathogen. Those GMO citrus lines would be expected to cost the growers annually 20% of each GMO tree's income, while UF would take 10%! The growers would later call this plan the "Rent-a-Tree Program".

GMW: Some might say Frank Dean is just spinning a line to sell his program. They will say, “Of course he claims it works.”

FD: I’m sure anyone who has not visited our grove might say that. And we don’t “claim” it works – we know it works, as evidenced by the 3,000 trees that were dying from citrus greening, which are now producing properly sized, juicy, and sweet Valencia oranges. To my knowledge, no one else has been able to accomplish that.

Thus far, in all our citrus trials, we have never had any money change hands for my work. We have not sold product, or charged for lab work, travel, or lodging. Everything was provided to the grower free of charge if they did the work and limited the herbicides applied.

For the future, we estimate the cost of our commercialized program to the grower at around $500 per acre. The cost of growing citrus is currently around $2,000–3,500 per acre, including what I consider to be counterproductive pesticides and fertilizers.

We ask the grower to stop spending that. We ask them to stop everything they have been doing, including applying pesticides, and to begin adding organic matter and microbials to the soil and allowing the trees time to heal. Pesticides block the uptake of certain beneficial compounds and minerals, so we supplement those. It really is that simple to get started.

GMW: Detractors aside, it seems fair to charge a fee for your products and services. Why have you not already done so?

FD: Ten years ago there were 1.5 million productive citrus acres in Florida. This year there are only about 600,000. The entire industry is in decline. The growers have less and less money. They sell land waiting for a cure.

GMW: Have you approached the UF, which is heavily involved in research to combat citrus greening, or the USDA, with your results? If so, how did they respond?

FD: Yes. Early on I demonstrated every visual sign of citrus greening could be induced with a glyphosate application. Symptoms included short internodes, tiny leaves, asymmetric chlorosis [loss of green colour in leaves], flowering out of season, and leaf and fruit shedding. I began to present my work to anyone who would listen – including the UF, USDA, and, the Florida Department of Agriculture.

For example, on a Thursday in early August 2014, I gave a presentation at the UF’s Fifield Hall, where the teaching, research and extension faculties for environmental horticulture were housed. Even though faculty members, administrators, graduate students, and field technicians were invited, only one faculty member attended. After a 90-minute PowerPoint presentation reviewing my successful work over several years in mitigating glyphosate-related problems in corn and soybean crops in the Midwest, the faculty member began her response by saying she was a believer in GMO technology. Not once during my presentation was the topic of GMO methods discussed, even though glyphosate is the herbicide most closely tied to GMO crop management practices.

On the following Saturday a UF faculty member told growers I had just spoken to that I was "batsh*t crazy".

On another occasion, in 2017, at the request of a concerned grower in Florida's Indian River citrus area, I travelled from Texas to the USDA's Horticultural Research Laboratory in Fort Pierce for a 9:00 a.m. meeting that the grower had arranged. When I arrived, I learned that the scientist I was to meet had instead chosen to travel across the State for a different meeting. I informed the grower, who contacted that scientist by phone, and the scientist agreed to meet later that day for a make-up meeting.

However, instead of meeting in a larger conference room where my presentation was set up for projection, I was restricted to the scientist's office, where several other USDA scientists were waiting. All declined to see my presentation or discuss my progress with reducing citrus greening symptoms while restoring fruit productivity by degrading glyphosate residues in the soil. Instead I was told that it was unnecessary for them to hear my presentation as they could tell beforehand whether something had "merit" or "smelled like a rotting dead fish".

GMW: Why do you think they reacted in this way?

FD: In my opinion they have painted themselves into a corner. The public funding for research continues to flow to the universities to study the supposed pathogen and/or to research GMO pathogen-resistant trees. This, along with the academic assurance of glyphosate’s safety, has led to a cascade of events, including:
* research money being taken for theory-confirming experiments
* academic acceptance that the bacterium causes the disease, and
* a refusal to consider that a mistake may have been made.

To my knowledge, there have never been any grants or funding for research that aims to determine if any commonly used pesticide could be part of citrus greening. In my opinion, that is flawed scientific method for understanding the cause of the problem, and it is illogical.

RW: In August 2018, at the annual meeting of the American Society of Horticultural Sciences in Washington, DC, Frank Dean presented several years of yield data, as well as DNA evidence, that showed that declining citrus trees treated with Frank’s protocol returned to productivity, while control trees continued to decline. The differences were statistically significant.

Frank estimates that the citrus greening research program has consumed well over 540 million dollars of funding without one recovered orange or sick tree, while Frank's work was accomplished without a single dollar of federal or state funding.

US Sugar, a company with large holdings of citrus land in Florida and a huge user of glyphosate as an end-of-season desiccant [to “dry down” the crop for easy harvest], has now signed a multi-year agreement with Texas A&M AgriLife Center to pursue a broader approach to citrus greening. Florida once had 6,000 citrus growers but the numbers now have fallen to about 1,200. To me it looks as if the future of US citrus production will be in Texas, while in Florida, contaminated citrus grove land is being scooped up by the housing industry.

GMW: Can your products be used by certified organic growers?

FD: The product used to remediate the soil is OMRI- [Organic Materials Review Institute] listed and can be used by organic growers. We are working on an organic program, but as yet, we have not found all the pieces for it.

NAS admits current approaches have failed

Dr Webb is critical of the hundreds of millions of dollars of taxpayer money that have been poured into the failed approaches to citrus greening. The National Academies of Sciences (NAS) conducted a review of the program, concluding in a 2018 report that while research supported by Citrus Research and Development Foundation (CRDF) and other agencies has “expanded knowledge” of the disease, “there have been no breakthroughs” in its management and that “the disease remains an intractable threat to the Florida citrus industry and has progressed from an acute to a chronic disease present throughout the state”.

The NAS is low-key about the potential for GM disease-resistant trees, remarking on “the difficulty of transforming most citrus genotypes” and the “significant obstacle” of the lack of reliable and rapid screening of GM plants. In addition, it says that developing disease-resistant trees via genetic engineering or conventional breeding “will take time, which a suffering industry can ill afford”.

Meanwhile, glyphosate continues to be used in America’s orange and grapefruit groves, the citrus industry continues to decline and die, and few seem willing to look into whether there is any connection between the two.

Asked about his predictions for the future, Dr Webb is not optimistic: “The damage done to the Central Florida aquifer and Lake Okeechobee from glyphosate and AMPA residues may finally stir public opinion to stop this herbicidal nonsense, though I have my doubts. It may already be too late to save the lake from the toxic algal blooms.

“To paraphrase Winston Churchill, Americans may be counted on to do the right thing, but only after exhausting all other alternatives.”

Frank Dean has long given up any idea of the government or universities stepping up to address what, in his opinion, are the underlying causes of the citrus greening catastrophe. While those in authority continue to blank him, he says his rewards come from working directly with growers and seeing dying citrus groves restored to health: “The groves we worked with had no fruit to pick when we started. One had gone four years with no harvest when we began. We are taking abandoned fields and bringing them back into production.”

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