In the summer of 2016, a farmer working in a banana plantation near Shfeya, a small community adjacent to the northern town of Zichron Yaakov, noticed signs of dehydration on the banana leaves. Fearing the worst, he immediately alerted experts from the Banana Industry Division at the Plants Production and Marketing Board, the agency overseeing the various aspect of produce farming in Israel.
Dr. Navot Galpaz, a subtropical crop researcher specializing in bananas, arrived at the plantation and soon made a grave diagnosis: the area was infected with Tropical Race 4 (TR4), a strain of Fusarium oxysporum, which is a particularly aggressive fungus that spreads the voracious Panama disease among banana plants.
Panama disease is a plant wilting disease that infects banana plants specifically. The pathogen is resistant to fungicides and, despite intensive worldwide research efforts spanning over 30 years, there is still no known way to defeat it. In agricultural circles, the destructive nature of Panama disease has earned it the name “Banana Killer.”
Galpaz immediately alerted the Plant Protection Unit at the Agriculture Ministry as well as Dr. Stanley Freeman of the Department of Plant Pathology at the Volcani Center, Israel’s top agricultural research institute, of his startling findings, and according to Freeman, the call did not come as a surprise.
“In 2015 we toured Jordan as part of a research program we were working on and we could see the fungus was already spreading there. We knew it had already been discovered in Lebanon as well, and we realized we were surrounded,” he told Zman Yisrael, the Hebrew sister site of The Times of Israel.
“It was clear to everyone that it was only a matter of time before it got to Israel,” Galpaz echoed.
Banana farming is one of the most stable and profitable agricultural sectors in Israel and the largest among the country’s plantation-based crops. Between 150,000 and 170,000 tons of bananas are picked annually across plantations spanning some 6,700 acres (27,000 dunams). The majority of Israel’s banana plantations are located in the north, in the Carmel region and the Jordan Valley, and there are smaller plantations in the south. About 4,000 people depend on the industry for their livelihood.
The only known way to prevent Panama disease from spreading is by using phytosanitary measures, which were immediately applied to the infected plot in Shfeya: Trenches were dug around the plot to isolate it from the rest of the plantation, the infected bananas were destroyed, and the plot was covered with polyethylene sheets. Freeman also tasked one of his students with monitoring the infected plantation and reporting on any changes.
Two months later, the killer fungus attacked two plots in the Jordan Valley, infecting over 15 acres (60 dunams). Israel’s banana industry went on alert.
A massive team of 30 experts from the Volcani Center, the Weizmann Institute of Science, and the Northern Research and Development Center — a regional agency that deals with, among other things, subtropical plant species — was recruited to tackle the complex challenge. In late 2018, it presented the Agriculture Ministry’s chief scientist with a comprehensive report that came down to one dark prediction: Panama disease is spreading and poses an existential threat to the local the banana industry.
An image problem
According to Freeman, farmers whose crops were affected by the killer fungus did their best to keep a low profile and downplay the issue, “but rumors started flying. People talk.”
These rumors are exactly what have banana growers worried.
“It’s a very complex issue for us,” said Ofer Ariel, who represents local banana growers at the Plants Production Board. “The consumer hears the word ‘disease’ and it naturally has a very negative connotation. To consumers, it sounds like there’s a problem with the bananas, that they’re not healthy.”
“This thing… you could say it’s a disease, but it’s a fungus. It attacks the roots of the banana plant and the plant dies. It has nothing to do with the quality of the fruit. But from a PR standpoint, this is of no help because all the consumers hear is that there’s a disease, so for them, that’s a problem.”
Panama disease, he stressed, is not dangerous to people who consume bananas — only to those whose livelihood depends on the crops.
Galpaz concurs: “It’s very important to emphasize this. The fungus doesn’t affect the fruit and even if it did — this fungus only infects bananas. It doesn’t infect any other crop and it certainly cannot harm humans.”
Image problems aside, Panama disease poses a serious dilemma for Israeli banana growers. Those who discover an infected plantation must report it immediately to the Agriculture Ministry, and any infected plot must be isolated and cordoned off, sometimes for decades.
“There is a real conflict here,” Galpaz said, “but obviously the right thing to do is to report it and I hope that’s what everyone does. Israeli growers work very closely with researchers, for this exact reason — to find solutions to such issues, release [bureaucratic] bottlenecks and increase the industry’s profitability. They know we’re on their side, and everyone knows that early detection is critical.”
What is it that makes Fusarium oxysporum such a formidable enemy, one that cannot be vanquished and can only be contained using extreme measures?
The pathogen attacks the roots of the banana plant, multiplies and releases toxins into it. The infected plant responds by producing a thick gel-like substance, clogging the root’s inner veins. This prompts it to dry up, wilt and eventually die. Once a plant is infected there is no known way to save it.
Worse still, as it turns out, Fusarium spores don’t die once they have consumed their host. The spores are exceptionally durable thanks to the double membrane that encapsulates them, allowing them to survive for decades even under extreme environmental conditions.
“A spore’s sole purpose is to survive the most extreme scenarios — high aridity, extreme heat, even radiation,” Dr. Dror Minz, head of the Soil, Water and Environmental Sciences Institute at the Volcani Center, explained. “Biology has developed these mechanisms and with a good enough capsule, they [the spores] can just sit around, at almost zero viability, and wait. Fusarium breeds extraordinarily tough spores.”
“These spores are designed to survive, so that’s exactly what they do. Even if you uproot the infected plants and wait a decade, you’ll still have spores in the ground,” Minz said.
Once a plantation has been infected little can be done, he said. “The banana plants must be uprooted and sprayed with herbicide, then petrol is injected into the plant, to kill it, and the plantation has to be closed until further notice. Sometimes 10-20 years,” said Minz.
Fusarium spores are so aggressive, so indestructible, that if they hit a banana plantation the entire area effectively becomes a dead zone for decades.
So far, the fungus has claimed six banana plantations in Israel.
“Theoretically, these plots can be used for other crops, because this pathogen only attacks banana plants, but the problem is that you can’t set foot in the area — you’ll be spreading the spores as you leave,” said Minz.
Minz warned that the killer fungus problem in Israel may be graver than anyone thinks: “We know about the infected plantations, but I can only assume there are areas where the disease is in its incubation period. We won’t know about those for another year or two.”
The risk is augmented by the fact that some farmers may opt not to disclose such contamination to avoid having their crops destroyed.
“There is a lot of money and many interests involved,” he said. “It’s not easy to tell a farmer who works hard and has spent a fortune on his plantation that it’s all gone.”
And growers and researchers may be fighting a losing battle.
“We’re looking at a very real chance that eventually, this will spread nationwide,” Minz warned. “All it would take is a strong windstorm to blow the spores or animals treading through the area. There’s no stopping it.”
So far, Israeli banana growers have spent upwards of NIS 2.5 million (roughly $700,000) to fight the killer fungus, including by installing electric gates and chemical decontamination pits around plantations to minimize potential contamination by vehicles driving in and out of them.
According to Ariel, only the bigger, affluent kibbutzim can afford to take such measures. Growers tending to smaller plots need the state’s help if they are to have any chance against this fungus, and if the state does nothing, the situation will go unchecked — potentially even unreported.
Galpaz, who heads the special task force trying to fight the fungus, says the next step is to deploy drones to detects Fusarium hot zones.
The usual suspects
So far, the Israeli banana industry has lost only 200 of its 27,000 dunams to the fungus, Galpaz noted. “Worldwide, it has already affected millions of acres, causing billions of dollars in damages.”
The last global Panama disease outbreak was recorded in 1989, when TR4, the latest incarnation of the killer fungus, annihilated vast banana plantations in Malaysia and Indonesia. The evil genius of spores has so far been able to outsmart any attempt to counter its devastating effects, consuming huge plantations in the Philippines — the world’s second-largest banana exporter after Ecuador — Indonesia and southern China.
No one knows exactly how TR4 arrived in the Middle East or how it made its way into Israel.
Minz ventured that one option is farmers who may have unwittingly brought the spore back with them from a visit overseas, sometimes by bringing back plants they didn’t know were infected. Ariel, for his part, points the finger at Jordanian boars.
“In the Jordan Valley, they found the fungus in places where wild boars crossed from the Jordanian side. They [the Jordanians] don’t monitor the fungus at all. A boar could have easily carried the spores in the mud stuck to it. I believe that’s how the fungus got here,” Ariel said.
Genetic analysis conducted at Freeman’s laboratory has been able to trace the origin of the TR4 attacking Israeli bananas to Jordan.
“Wild boar, vehicles, people, produce — every guess is as good as the next,” Galpaz said.
The ‘holy grail’ of bananas
Until the early 20th century, people consumed mostly Gros Michel bananas but the cultivar was all but wiped out by Panama disease in the 1950s. Since then, people have been eating Cavendish bananas, considered relatively resistant to Panama disease.
Then came TR4.
“Growing a single cultivar, or monoculture, as it’s called, is the source of all evil in today’s global agriculture,” Minz said. “It’s not just bananas. It’s all crops. Farmers want unity because it’s both labor- and cost-effective. It may sound bad, but without monoculture, the costs of cultivating and harvesting crops would be so high we wouldn’t be able to feed everyone. Free-range chickens and organic crops are great of you can afford it, but you can’t feed humanity as a whole like that.”
Monoculture, however, makes produce extremely vulnerable to the pathogen. TR4, for example, poses nothing short of an existential threat to bananas. Still, Minz does not believe it will wipe banana plants off the face of the earth in the next few years.
“I think honest efforts are being made all over the world to look for a solution to this problem, but it won’t be black and white. If we can sustain the banana industry in Israel with minimal damage, at least for the next few years, until we figure out a genetic solution, it will buy us a few decades,” he said.
Until the pathogen mutates again, that is.
“We just need long enough to develop a resistant banana. But even the resistant cultivar will eventually encounter an even more durable fungus. It’s the same as with violent bacteria and antibiotics,” Minz said.
While Minz’s team is trying to find a biological countermeasure to the fungus, Galpaz’s team is trying to cultivate a Fusarium-resistant banana.
“That kind of banana — that’s the holy grail of the global industry,” Galpaz explained. “Bananas are the most popular fruit in the world and Panama disease is the industry’s biggest problem. Do the math — there’s a lot of money involved here. Researchers from all over the world have been trying to develop a fungus-resistant banana for years, to no avail.”
“Israel is at the forefront of the global effort, but if there is excellent collaboration and knowledge-sharing between the various research institutes when it comes to dealing with the disease, when it comes to developing a resistant cultivar — because there’s big money involved — there’s less cooperation,” he said. “People are more guarded when it comes to money.”
According to Galpaz, his research is focused on developing a fungus-resistant banana using genomic editing technologies, which facilitate targeted change in gene activity.
“Produce that is cultivated using this method can be mass-marketed in Israel and elsewhere in the world, unlike the products of genetic engineering, which are banned,” he said.
Genetically modified organisms (GMO) are currently grown in 26 countries worldwide. In 2015, the majority of European Union member-states decided to ban the cultivation of new GMO crops within their borders, and Russia issued a ban on both cultivation and imports. Other countries, such as China, Japan, and Canada, restrict GMO products, but only until they pass regulatory standards.
Israeli law permits the development and growth of GMOs for research purposes and while it bars GMO growth for commercial purposes, it states that GMO products may be imported, sold, and used in the production of food and pharmaceuticals in Israel. The Chief Rabbinate has also weighed in on the issue, ruling that the use of GMO ingredients in food does not affect its kosher status.
To date, however, Israel has not passed legislation specifically regulating the labeling of GMO components in food.
The effort to find a biological answer to the TR4 threat takes place in a secluded greenhouse at the Israeli government-linked Volcani Center in Beit Dagan, near Tel Aviv.
“It’s very difficult to work with this fungus because it has to be quarantined,” Minz explained. “All work has to be done in a designated laboratory with special disinfectant measures for those leaving it. Everything that comes out of here — water, waste — is destroyed. It’s not that we have banana plantations around us, but if someone transports so much as one microscopic spore on their shoe, it could end up in a banana plantation.”
Minz noted that the hunt for biological solutions is in its infancy. He stressed that every step of the research, especially anything involving bacteria or any substance derived from it, undergoes rigorous scrutiny to ensure they are completely safe for humans and the environment.
If the team is able to synthesize a bacterial variant that stymies Panama disease, it could apply for a patent, which would mean serious dividends for Israel, the Volcani Center and Minz himself, as it will brand him the “superman” of the banana industry.
Still, forgetting to dip one’s boots in the disinfectant solution leading out of the lab could see all of these efforts wither and die, literally, because all it would take to eliminate Israel’s banana industry is one errant yet highly determined spore.
This article first appeared in Hebrew on The Times of Israel’s sister site, Zman Yisrael.