Whether it be in the U.S., Brazil or China, citrus greening disease has caused billions of dollars in damages to growers and continues to threaten farms in new regions, most notably California.  As one of the largest growers in Florida, Southern Gardens Citrus hit the ground running in search of solutions when the bacterium was found on one of its properties in 2005. The most effective potential tool so far has been genetic modification, with a spinach gene implanted in oranges, grapefruit and lemons to make them citrus greening-resistant. But will biotech be a silver bullet for this suffering industry?

"If we could find a solution other than biotechnology that would solve this problem tomorrow, we would be at the forefront of working on it," says Southern Gardens Citrus president Ricke Kress, adding the group was indeed studying disease control and mitigation on many levels.

"But if biotechnology is the answer, then the industry should have that alternative to consider."

Weighing up the sensitive consumer issue of GM acceptance and the urgent need for agricultural solutions to the disease - also known as Huanglongbing (HLB) - Kress says it is important for the public to better understand the industry situation and the authorities' scientific conclusions on safety.

"Even though we've had trials in the ground since 2009, we're now just getting to the point where we're seeing fruit being grown by these trees. From a quality and scientific perspective it compares very well," he says.

"From a taste perspective, there are no major issues, but in a citrus tree when it's young the fruit taste isn't as mature as it will be in three or five years."

The flavor of an HLB-infected citrus fruit however is extremely different.

"An infected orange is an immature orange. It just doesn't ripen to the same level and therefore is less sweet and more acidic," Kress says.

"It can have an impact on the flavor, and then depending on the individual who will taste this product they may have different flavor descriptors that it's bitter, but overall it's just not as sweet as an uninfected orange."

As part of an Environmental Protection Agency (EPA) experimental use permit granted in April which will allow Southern Gardens Citrus to go past a 10-acre field trial, the agency granted the company what is called a 'temporary tolerance exemption'.

"What that means is the EPA has evaluated all of our research and data related to the spinach defensin in technology, and has indicated that the oranges that will be produced from this technology will be safe to consume," Kress says.

"Probably the most important factor in all this is a spinach defensin gene is already in the food supply - it's already approved. When you start looking at other genes - which we've done and continue to evaluate - you want something that is going to work through the approval process, both regulatory-wise and consumer-wise.

"If you have a gene that is an allergen, that won't be accepted from a consumer perspective. If you have a gene that won’t be accepted by religious groups, that doesn't work, so as we talked with Texas A&M [University], the spinach gene had a lot of favorable characteristics for our interests."

Building citrus trees

The April approval for larger trials marked 10 months since the grower's application to the EPA, and meant the company could finally start planning beyond its current research of small plots, sometimes with just 20-25 trees and in some cases as much as 300.

"It's an extensive process because we're dealing with a tree – we're not dealing with an annual plant. You have to build the tree and then grow it to be able to evaluate it, so it has taken a lot of time," Kress says.

"When I say we’re building a tree, an orange tree or any citrus tree is two parts; it's a rootstock and a scion. Our technology basically involves resistant scions that we are generating budwood off that we will ultimately graft onto a rootstock.

He says the research team is also investigating whether there is a need for genetically modified rootstocks, but for now the focus is on having trees ready to put in the ground in the spring of 2016.

"We might have trees ready to go before the end of the year but we don't want to put them in the ground in the winter time. There are a lot of different factors we have to consider when we're doing this work," Kress says.

A GM tree (left) compared to a non-GM tree (right). Photo: Southern Gardens Citrus

If approval processes for other GM fruits - such as Okanagan Specialty Fruits' non-browning Arctic apples - can be taken as an example, it could be a while yet before Southern Gardens Citrus' crops are approved by the United States Department of Agriculture (USDA) for commercial production.

"Timing-wise, I'd like to say we're dealing still in years because a couple of factors – it takes time to grow trees. It's going to take time to grow enough trees to make a commercial impact, and we're optimistic that within about three years we think we can have enough data and information to get full approval.

"We also have other technology and other things we’re looking at, other developments and techniques in the groves to keep our trees productive and alive until we can get to this new technology."

Down the biotech path

Kress admits he didn't know a lot about the disease when it was first confirmed in Florida in late 2005.

"It was found in one of two commercial groves in Florida, and one of those groves was ours. We knew it was a disease that had been in the world for several years, and it had been detected and confirmed in Brazil about 18 months before that.

"It was coming on the heels of canker, which had been detected as a problem here in Florida, so agriculturally it was presenting a lot of questions about what was going to happen to our groves, tree health and everything that went with it.

"So we became very active in trying to learn as much as we could about this disease – what could we do? We headed down to Brazil right away, met with growers, and the best practice at the time was really a three or four-pronged approach."

This meant inspecting groves frequently, removing infected trees, controlling the insect vector Asian citrus psyllid (ACP), and only replanting disease-free trees.

"We and others in the state adopted the practice to some level; it all depended on the individual growers, and that's how it started" Kress says.

"We are one of the largest growers and processors in the state of Florida, and we have a significant juice processing operation that can process 20 million boxes of fruit a year into well over 100 million gallons of not-from-concentrate orange juice - that's all it does.

"So we have an asset that is very dependent upon a sufficient and consistent fruit supply. We knew we needed to start looking at research capabilities and what solutions to this disease could be down the road."

It was in that analysis that questions were raised about whether biotechnology could be a solution to the disease.

"We started down that path in 2006," Kress says.

Beyond the fruit: International regulations and labeling

If Southern Gardens Citrus starts planting commercial groves of GM oranges, the implications will be much broader than its domestic juice business.

It will also have to contend with juice and citrus byproduct regulations at home and abroad.

"We aren’t only worried about the orange juice we produce, because we use every part and piece of the orange we receive, either as juice or as a byproduct, all the way through to the remaining peel, which is converted to cattle feed," the executive says.

"So we have to adjust this in all areas – we are now working on understanding what the global requirements in various markets for biotechnology are as well."

Photo: Southern Gardens Citrus

On the positive side, there is also potential for the group to export its patented technology to other countries where HLB exists.

"We have the exclusive rights to this technology in citrus for the world," he says.

"There have been lots of other discussions but there is nothing definitive. Quite honestly, we've got to take care of proving we have what we think we have."

Another controversial issue in the U.S. is GM labeling, with consumer rights groups calling for transparency and a right to know when they are eating biotech foods.

"What's interesting is in the food supply presently, the estimates are somewhere between 80-85% of the food in the market today in the United States is done with biotechnology," Kress says.

"When you look at corn, soy and sugarbeets, those three products are contained in a lot of different products that are already out there, so if a mandatory labeling program came into play, then the bulk of the food supply could potentially be labeled with biotechnology."

This however is not the case in the produce arena bar a few crops, and consequently any juice that is completely natural.

"In the 100% juice arena where we compete, you are right, but when you go into the full juice category where there are diluted beverages with sweeteners, if high fructose corn syrup is added to it, then it is impacted," Kress says.

California greening

On the issue of a recent citrus greening detection in California, the Southern Gardens Citrus head laments the challenges ahead for his colleagues on the other side of the country, and does not believe it will be smooth sailing.

"Florida is very severely affected by the disease, Texas is very much affected by the disease, and California has the opportunity to deal with this disease from Florida's and Texas' experience," he says.

"Now they're starting to find infected trees as well. It's a problem that's going to the impact the United States citrus business, as well as the rest of the world.

"The insect is there, and if you've got infection it's going to show up, unless somebody can come up with a solution soon."

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