MR. TOM GJELTENThanks for joining us. I'm Tom Gjelten of NPR. I'm sitting in for Diane Rehm. Americans eat more bananas than apples and oranges combined. Globally, banana exports total nearly $9 billion a year. More than 400 million people rely on the fruit as a primary source of calories. But now, a deadly fungus is spreading through banana plantations around the world leaving growers and scientists scrambling to find a solution.

MR. TOM GJELTENJoining me here in the studio is Robert Bertram of USAID's Bureau For Food Security, from KPCC in Pasadena, California, we have Dan Koeppel. He's the author of "Banana: The Fate Of The Fruit That Changed The World." And from WLRN in Miami, Randy Ploetz, a plant pathologist at the University of Florida's Tropical Research and Education Center. Hello to each of you. Thanks for joining us.

MR. ROBERT BERTRAMGood morning.

MR. DAN KOEPPELGood to be here.

MR. RANDY PLOETZGood morning.

GJELTENSo do you care about bananas? I bet you do. Join our conversation by calling 1-800-433-8850. You can email us, drshow@wamu.org. You can send us your questions, your comments through Twitter, our Facebook page or our website. Randy, let's start with you. Tell us little bit about this deadly fungus. I think you've been credited with discovering this. It's been spreading around the world. What is it? What does it do to banana plant?

PLOETZYeah, it is a fungus. It's a soil-borne fungus and in 1989, I received samples from Taiwan that genetically was different from anything that we had collected before. So at the time, it was, you know, a novel genetic group, but we didn't think much of it. Shortly after, in 1992, I received samples from Sumatra and the same genetic group of the pathogen and we started scratching our heads. Very quickly, by the middle of 1992, then this new fungus, new race of this pathogen started popping up around Southeast Asia and started killing Cavendish, which was very unusual.

PLOETZCavendish, in other areas of the world, is very resistant to this disease, but not to this new race and we call a Tropical Race 4 now. It spread to consolidated in Southeast Asia very rapidly. Within a decade, it had spread to several different countries there. And then, more recently, as you eluded to in your introduction, it's popped up in Mozambique and several countries in the Middle East. So we're very concerned about this movement and what it might potentially do in the future to export production of Cavendish in the Americas.

GJELTENWell, we're concerned, as Americans, about what's in our own supermarkets. Dan Koeppel, where we have seen this fungus spreading, what has it done to local production supply of bananas?

KOEPPELWell, it's been devastating wherever it spreads. For example, in Australia, plantations have had to be destroyed and that's meant hardship for farmers. It's meant increases in banana prices and so it's a real crisis. There's no cure for this and the only real solution to stopping it is to actually, you know, sunset these plantations and that's a huge problem.

GJELTENAnd is that happening in, for example, Southeast Asia?

KOEPPELIt is. It's happening wherever this fungus is found. Ultimately, these plantations end up ceasing to grow bananas where the fungus is.

GJELTENSo if you're living in Southeast Asia, Dan, you know, as a consumer, do you see the price of bananas going up? Are you only able to get bananas imported from somewhere else? How has it affected consumers in those areas?

KOEPPELWell, I wouldn't say in Southeast Asia because there's a wide variety of bananas grown there, you know, village bananas. But in Australia, banana prices have gone up and banana prices, if this hits Latin America, and it likely will, we don't know when, will go up in the United States. Banana prices are very sensitive to all kinds of fluctuations. For example, flooding in Ecuador raised banana prices to about a dollar a pound in 2008.

KOEPPELSo we know that this commodity product is very sensitive to prices and consumers are looking for bananas to be cheap. There's a big question as to whether consumers will buy expensive bananas.

GJELTENYeah. Randy, what do -- how many, let's say, tons of bananas and plantains are produced each year and to what extent has that global production already come down or been affected by this disease?

PLOETZWell, the total production every year is approaching 150 million metric tons. That's a lot of fruit. And the importance of Cavendish is that about half of that 150 million tons is Cavendish and it's -- about half of that total is exported bananas, but the rest is locally consumed, locally grown Cavendish bananas and they are very important for local consumers where it's an important cash crop.

PLOETZThe bigger question is how has it affected production in other areas? And the two major areas that have been affected, Mindanao Island in the Philippines and in China. China, it's mainly for local production, but about 100,000 hectors have been destroyed there. It's hard getting exact loss figures from there. And in the Philippines, the Philippines is actually one of the major exporters of bananas in the world and I was in Mindanao about a year and a half ago and production there has been severely affected.

PLOETZBut again, it's hard getting figures from that country so the eye test says yes, major impacts so far, at least in those two areas, but not so much in other areas because, as Dan indicated, those other areas grow different types of bananas, not Cavendish. Again, the concern is when this spreads to Latin America, where Cavendish is grown for export primarily. Most of those major producers are in the Western Hemisphere. And, again, we don’t have this problem there yet.

GJELTENAnd Rob Bertram, do you have -- it's important, I think, to keep this in layman's terms and the bananas that we see in supermarkets here in the United States, what percentage of them are of this variety, the Cavendish variety that is especially vulnerable to this fungus?

BERTRAMI suspect that my colleagues on the phone might even be better at this answer than I am, but I can tell you that it's very, very high. I would say something of around 95 percent with the sort of niche market bananas of certain types being sold, red bananas, small finger-type bananas to a specialty market.

GJELTENBut the big Chiquita, yellow bananas that we are so accustomed to see hanging on the hook there in the supermarket...

BERTRAMCavendish.

GJELTENThey're all Cavendish. And Dan, tell us a little bit about the Cavendish banana. I mean, I'm not banana expert. I did say in my intro that some people, when it was introduced, considered it an inferior banana. What's the deal with Cavendish bananas? I mean, they certainly look pretty, don't they?

KOEPPELThey look good and that's one of the reasons they were selected. They are relatively tough. Banana has to go a long way from where it's grown to the market so it has to survive shipping. It has to ripen at the right amount of time. The Cavendish is not what you'd call the world's most delicious banana. There are over 1,000 varieties. India is the world's most banana rich country with over 600 varieties and in India, they call the Cavendish the hotel banana because it's only served to tourists whose palettes aren't interested in anything else, apparently.

KOEPPELBut it's not a great banana and it's actually not even the first commercial banana. An earlier version, the Gros Michel, that you mentioned went commercially extinct, was a much better tasting banana and a much easier banana to grow, expect that it was susceptible to the first version of this disease.

GJELTENSo Dan, you've written a book about bananas. But just bring us down to earth here. What's, in terms of the history of the banana, obviously it's not produced in the United States or at least it's not produced in Northern United States. I don't know if there are parts of the United States where it's grown. But, you know, this is largely a fruit that is imported. When did Americans begin eating bananas and when did the banana become so important to Americans?

KOEPPELYeah, the banana is really, you know, both an agricultural miracle and a business tragedy. It is the most popular fruit in the United States. It is the cheapest fruit, yet it's exported from far away, has to shipped under refrigeration. The banana was introduced, you know, as we know it, in 1876 at the Philadelphia Centennial Exhibition. From there, a couple of entrepreneurs said, hey, maybe we can find a way to bring bananas to the United States and sell them for less than apples. It seemed impossible, but by 1900, the banana was on its way to passing both apples and oranges and it became Americas favorite fruit through the marketing genius of a couple of entrepreneurs whose company is now called Chiquita.

GJELTENAnd where were those bananas produced?

KOEPPELThe original ones came from Jamaica, but they quickly ran out -- banana demand got so big that an island like Jamaica couldn't support so they went on to Costa Rica. They built a national railroad. They spread throughout Latin America and South America as well. And pretty soon, you know, over 20 countries were growing bananas and were being controlled by these banana companies.

GJELTENWell, Rob Bertram, you are the chief scientist at the Bureau For Food Security at USAID and food security means, like water security or energy security, it means the security of this very important source for people. To what extent do people around the world depend on bananas as a food source, as a necessary food source?

BERTRAMWell, it's an interesting story because there is both the food dimension of banana production and the livelihood dimension. And in Africa...

GJELTENA lot of them are grown by small...

BERTRAMExactly. In Africa, 95 percent of bananas are grown by small holders and so we think about the threat to banana production not only in terms of food, which is significant, but also in terms of incomes. And, of course, many people who produce bananas rely on a productive crop to sell and then purchase the food and of diverse types that they need in the marketplace.

GJELTENRob Bertram is chief scientist at USAID's Bureau For Food Security. The topic this morning is the uncertain future of the banana. And it's a topic, I'm sure, that a lot of you care about. Remember, our phone number's 1-800-433-8850. We already have some people trying to reach us. My other two guests are Dan Koeppel. He is the author of "Banana: The Fate Of The Fruit That Changed The World."

GJELTENAnd from Miami, Florida, Randy Ploetz. He's a professor of plant pathology at the Tropical Research and Education Center at the University of Florida. He is an expert on this disease that is jeopardizing., threatening the future of the bananas that we eat here in the United States. I'm Tom Gjelten. We're going to take a short break. We'll be right back.

GJELTENTom Gjelten is here. I'm hosting Diane Rehm this hour. Welcome back. And we are talking about the uncertain future of the banana with my guests Robert Bertram from USAID and, from Pasadena, Calif., Dan Koeppel, author of "Banana: The Fate of the Fruit That Changed the World," and, from Miami, Fla., Randy Ploetz, professor of plant pathology at the University of Florida.

GJELTENWe actually have a couple of tweets from Florida. Eduardo wonders whether Cavendish is the only variety of banana affected. And why is it, he wonders, that Cavendish is the most commercially prevalent? Another tweet from Florida, I live here in Florida and many delicious bananas are grown here that are not Cavendish. And this listener is wondering whether struggling citrus groves could be converted to bananas. Randy, is Cavendish the only variety affected? And what options are there for banana growers, whether in Florida or somewhere else?

PLOETZWell, in fact, Cavendish is one of several different types of banana that are affected. Tropical Race 4 has a very wide host range. So they're -- some of dessert finger bananas that Rob talked about are susceptible. Some of the other dessert bananas that are very popular in Southeast Asia, Pisang Barangan, is also susceptible. So it's got a fairly wide host range. And then those bananas that were affected by earlier races of the pathogen are also affected. So Cavendish, again, is not the only banana affected.

PLOETZThere are a lot of other bananas out there that are not susceptible and that they do taste good, on the stand on the points that have been made so far about, you know, Cavendish being relatively poor tasting banana. But the thing that Cavendish has going for it is it's very, very productive. It's the most productive, naturally-occurring banana that's out there. And the exporters have got the production and trade in this banana down to a high science. Replacing it with something else that would yield as well as Cavendish is a monumental task and no one has been able to do it yet. There are other red bananas that are out there. This is a long topic for discussion.

GJELTENMm-hmm.

PLOETZBut they don't have some of the attributes that Cavendish has. So, long story short, yeah, there are other bananas out there. They could be produced but not as profitably. And then, for the citrus areas in Florida, those get cold winters and banana does not like cold weather.

GJELTENYeah.

PLOETZSo that would be a problem as well.

GJELTENOkay. Rob Bertram, we were talking before the break about how many people produce bananas, depend on bananas, whether for economic livelihood reasons or for nutritional reasons. And, you know, we, in the United States, think of slicing up our bananas and putting them in cereal or maybe having a banana after our run for a little bit of energy pickup or something. Maybe, you know, a banana, you know, sundae or something like that. We associate it sort of as a -- not a luxury fruit, but something that is not central to our diets. You were saying that's not necessarily true for other people.

BERTRAMNo that isn't the case at all. There are parts of tropical Africa, the equatorial regions of high rainfall, where the whole food system is centered around banana production -- different types of bananas, not a dessert banana like Cavendish. And in addition to that -- so to think of the banana as being the main course, instead of something you eat around the edges of the meal or on top of your cereal -- in addition to that, we know that 400 million people depend on banana production for their livelihood.

BERTRAMSo this is a double-whammy, in a sense, to have a threat to one of the world's major food crops, on the one hand, combined with a threat to one of the major sources of incomes for hundreds of millions of small-holder -- often small-holder farmers in the developing world.

GJELTENDan, I'm interested in the symbolic importance of the banana. You know, I lived in Germany and worked a lot in Eastern Europe around the time of the collapse of Communism. And you probably know this story. But consumers in the old Soviet Bloc did not -- were not able to get bananas in their stores. And when they -- when Communism collapsed and things changed over there, one of the things that got them so excited was that for the first time in their lives they were able to eat bananas. And I remember there used to be -- the banana became the symbol of political change in Eastern Europe. There were even bumper stickers where people celebrated the change in Eastern Europe with the banana.

GJELTENIt's clearly a fruit that sort of resonates with people around the world for one reason or another.

KOEPPELYeah. And it's a really interesting idea. Because, you know, on the one hand, the banana, as we see it, is sort of the most mundane, ordinary, boring fruit you could think of. On the other hand, it is this strange thing that was unheard of. And it's tropical. It's exotic. So it's both boring and exotic at the same time. I think, to many people who get imported bananas and those folks in Eastern Europe it represented sort of a sense of availability. If bananas could come to Eastern Europe from so far away, then, in a way, almost anything was possible. You know, people could get cars and washing machines and refrigerators too, if the impossible task of importing a banana from so far was able to be accomplished.

GJELTENWe're getting so many interesting questions about this and a really variety of questions. Katie wonders, she sent us a tweet, is it true that banana flavoring in things like candy is actually based on an older variety of banana? Is that true, Dan?

KOEPPELIt is true that the official banana flavoring was based on Gros Michel. But, you know, as the father of a five-year-old and someone who's tasted a Gros Michel banana actually, I can tell you that Laffy Taffy and the Gros Michel banana taste nothing alike.

GJELTEN(laugh) Randy, we have an email from Christopher in Brooklyn. I'm going to give this one to you. Why was the growing of the Cavendish banana allowed to expand to so much of the world? After Gros Michel bananas were wiped out by disease, plant growers should have diversified their banana production. Will producers make the correct choice to diversity this time?

PLOETZWell, the diversification thing brings up again this profitability issue. And Cavendish, again, can be grown very profitably. There are other bananas, if you want to diversify, that could be put in, in the place of Cavendish now. But, again, you would not be able to get the profit margins that you would with Cavendish. So that's the crux of the matter, the cost efficiency. It's plain and simple.

GJELTENOne more question for you, Dan. This is -- well, she doesn't say where she's from -- have we -- we haven't seen a shortage of bananas in the Southeast United States yet. But there is a definite shortage of organic bananas. Is there connection between this shortage of organic bananas and what's going on?

KOEPPELI would say probably not, since those organic bananas are coming from Latin America. But organic bananas can only be grown in a limited range of areas because you can't use the conventional pesticides that are used to prevent other banana diseases. You have to have special growing areas where those diseases aren't likely to come up. So I think occasionally people will see fewer organic bananas than conventional.

GJELTENSo, Rob, this is clearly a concern for our listeners and for consumers all over America. And the big question is, what has been done, what can be done, what is being done to stop the spread of this disease and protect our bananas?

BERTRAMSo what we've seen that can happen, Tom, is that in places like Australia or parts of Asia, a rapid response can be mobilized. It's far more challenging in a poor, developing country like Mozambique. Mozambique is, however, one of our focus countries, under the U.S. government's global food security initiative called Feed the Future. And in Feed the Future, we are investing in ways to, A, assess the challenge of containment in Mozambique, or eradication. Look at alternative practices around, say, rotation with another tropical crop, like pineapple, which would have the effect of eliminating or helping to eliminate the spores from the fungus.

BERTRAMAnd finally, also thinking about research approaches. We invest in -- we have science and technology in this country that could actually help solve banana problems facing small-holders in the developing world. So that's also on the horizon. And there are some promising approaches that we could look at.

GJELTENSame question to you, Randy, as a plant pathologist. What is being done and what would you recommend be done to stop the spread of this fungus?

PLOETZWell, I guess I'm not as optimistic as Rob. This disease has been beat to death as far as looking at different ways of managing this problem.

GJELTENHmm.

BERTRAMAlternative crops, biological control, chemical measures, there are not fungicides -- there's a long list of things that have been tried exhaustively. And with the exception of resistant bananas, none of these have really worked for a long time. There are a series of bananas out of Taiwan now, we'll probably talk about those soon, they're called the somaclonal Giant Cavendish varieties. They tolerate the disease, but they still are affected by it. And you have to grow them -- replant them every other cycle. And then the fruit that are produced by them are not marketable in traditional marketplaces. So it -- there is no good replacement for Cavendish.

BERTRAMAnd if you go to a field that has this pathogen in it, is infested with it, it stays there for a very, very, very long time, up to 40 years in some...

GJELTENHmm.

BERTRAM...some of the reports I've seen. So you can't -- once the pathogen is there, you can't get rid of the pathogen. And what you can be -- can be grown there is severely limited by the presence of that pathogen.

GJELTENHow virulent is that pathogen? How easily does it spread?

BERTRAMOh, very easily. I've got a colleague in Holland, one of the things he did recently, you know, the question is how did it go from Southeast Asia to the Middle East and Africa? He went to China and wore some sneakers, went into a field that was affected by this pathogen, came back, did not clean off his shoes and from the mud on his shoes was able to recover the pathogen. We think that that and perhaps other means of moving this pathogen around, it's so easily moved, that it -- that's how it got from Southeast Asia to the Middle East.

BERTRAMAnd then, if the alternative thing, this is possible, how's it going to jump the Atlantic? All you have to have is someone go to some area in the Middle East or Southeast Asia and go to Latin America with muddy shoes or soiled machinery and the same thing can happen. So a great concern. This thing is very, very easily moved.

GJELTENDan, Rob was talking earlier about how many small land-holding farmers depend on banana production. But of course there are really big banana company producers, Dole and Chiquita. How concerned, how alarmed are they by this?

KOEPPELWell, you know, if absolute wall of silence is a sign that they're hiding their concern, then they're hiding their concern. Chiquita actually did talk about this and mentioned it as a great concern. But Chiquita was recently taken over by a Brazilian company and has sort of reinstituted the wall of silence. But they have to be worried. And I know for a fact that Chiquita is doing some private research on alternative varieties in Latin America, trying desperately to find something. Look, this is their main product.

KOEPPELAnd these are company -- the banana is a commodity. These are companies where, you know, a slight shift in supply or a slight rise in price or cost of production is going to make huge differences to their profits. They're very worried about what's going to happen.

GJELTENHave you seen it in their stock prices yet?

KOEPPELYou haven't seen it in their stock prices yet. But -- and I think that's one of the reasons they're sort of parsing this very carefully.

GJELTENSure.

KOEPPELThey can't say it's going to be a disaster but they can't say it's going to be all good either. Either way, it's going to hurt their stock.

GJELTENWell, I'm sure they're not too happy with you saying that here, this morning, on "The Diane Rehm Show." I'm Tom Gjelten and this is "The Diane Rehm Show." Okay. Here we have an email from Alan in Durham, N.C., who says that he doesn't buy organic bananas because the Environmental Working Group has them on their top-10 safe list. I'm not sure what exactly that means. But he's concerned that, as banana growers become more aware of this problem, that they're going to use -- be more tempted to use fungicide on their plants and it'll be harder to find organic bananas. Do you have any thoughts on that, Rob?

BERTRAMWell, there are some fungal diseases of bananas, like Black Sigatoka, which are routinely controlled with fungicides. And while there are some fungicides that can be used with Fusarium, I don't believe that this is considered a practical approach. More importantly, many of the farmers that we would be concerned about -- small-holder families across Africa and other parts of the world -- may not be able to access the kinds of fungicides that would be needed even if they could control it.

BERTRAMAnd the other thing that we haven't talked about to a great degree yet is the fact that this strain of Tropical Race 4 Fusarium attacks a wide variety of bananas. And we need to understand more about how susceptible the various kinds of bananas that are grown in small-holder systems in particular but also, I mean, in potentially in large, but mostly those are Cavendish -- we need to understand just how impactful this is going to be. And then I ultimately agree with Randy that the real response lies in somehow finding a durable source of resistance. And we've managed to do that in some other instances, other crops. The banana has special challenges and that's another interesting area of discussion.

GJELTENLet's go now to Gary, who's on the line from Sterling, Va. Hello, Gary. Thanks for calling "The Diane Rehm Show."

GARYThank you. I'm thinking that with the higher level of CO2 content in the atmosphere that we're going to have more thallophytes or funguses, problems with them. And we should be using the CO2 for fracking because we could, you know extract from the atmosphere and it's a great fracking medium.

GJELTENWow.

GARYAnd (word?) are at 9,000 feet down. Nothing beats a grilled-banana sandwich, I'll tell you that, with cinnamon. Oh.

GJELTEN(laugh) Okay. We've got -- you've got a lot of different strains going there, fracking, sandwiches, Randy, climate change. How about that, Randy? Is the higher levels of CO2 in the atmosphere conducive to the growth of fungi?

PLOETZWell, it -- I was advising a student recently and they asked about climate change. And climate change definitely has had an impact on other plant diseases, coffee rust is a good example. But for this crop, in particular, the projections for the tropical areas of the world are that those areas that grow bananas actually are going to expand and it's going to be more easy -- easier to produce bananas as global temperatures rise and rainfall patterns change. So it doesn't necessarily address the disease issue but the crop itself is going to be grown in more areas.

GJELTENSo, Rob, climate change could conceivably be a factor here. What about globalization? And how does globalization affect how quickly something like this can spread around the world.

BERTRAMWell, it's a case in point and why Mozambique is such a worry. Mozambique speaks Portuguese, as does Brazil. Many people go back and forth between the two countries...

GJELTENYeah.

BERTRAM...by air travel. This is -- and we already heard about how somebody's shoes can carry this from one country to another. So globalization contributes in that respect. It also contributes in a sense by virtue of the fact that there becomes a global standard, as Cavendish has become. It's not necessarily a bad thing. It's for good reasons. It's productive. It's durable. It ships well. But if everyone is growing the same thing, as you've suggested earlier or as one of the callers did, there is a genetic risk there.

GJELTENMm-hmm.

BERTRAMBut unfortunately, banana is a very challenging crop plant to devise alternative strategies on because of the way it breeds or almost doesn't breed. It's a very complicated to try to improve genetically.

GJELTENAnd as Randy was explaining earlier, this is a very virulent fungus that is hard to eradicate. Rob Bertram is chief scientist at USAID's Bureau for Food Security. Our other two guests are Dan Koeppel, he wrote "Banana: The Fate of the Fruit That Changed the World," and Randy Ploetz, he's a plant pathologist at the University of Florida. We're going to take a short break here. We have a lot more calls, people worried about the future of their bananas, for good reasons, it turns out. I'm Tom Gjelten. Stay tuned.

GJELTENHello again. I'm Tom Gjelten. I'm sitting in for Diane Rehm this week, and we're talking about bananas, the future of bananas in this country. And we're concerned about that because of a fungus that is spreading around the world. I have three guests. Rob Bertram is here from the USAID's Bureau for Food Security. Dan Koeppel is on the line with us from California. He's the author of "Banana: The Fate of the Fruit That Changed the World." And from WLRN in Miami, Fla., we have Randy Ploetz, a plant pathologist at the University of Florida.

GJELTENAnd, Randy, I have an interesting email here from George who is a former banana farm manager for Chiquita on plantations in Guatemala and Panama. And he worked extensively there with Cavendish bananas. He's actually got three questions which I'm going to reel off really quickly. First of all, he says that he's used many different practices to control fungi from aerial spraying to what I assume are some fungicides, Sigatoka, methyl bromide, and then the third thing, leaving areas fallow, including underwater, in order to protect against Panama Disease.

GJELTENAlthough he points out that in the past the transnational banana companies held vast reserves of land, so leaving thousands of hectares, fallow was an option, but with growing populations, nationalization of land, competition from other industries, there doesn't seem to be such a viable means anymore to shift production away from the Cavendish to other crops without affecting the commercial supply. And then finally, he wonders about genetic modifications. So when he talks about spraying, Randy, he -- I'm wondering if he's talking about protecting against other fungi rather than this particular one that you're talking about, for example.

PLOETZVery definitely. Yeah. And Rob mentioned that there's a disease called Black Sigatoka or Black Leaf Streak or Sigatoka Negra. It's a serious foliar disease of Cavendish. And any area in the world where you grows Cavendish bananas and have significant rainfall, this is a really serious problem. So banana producers in those areas routinely fly by fixed wing aircraft or helicopters, fungicides that -- they've got a very precise routine for doing this, to manage that disease. So...

GJELTENBut that's not gonna work in this case.

PLOETZNo, it's not. No, no. And then going to a second point, he talked about methyl bromide and flood fallow. In both those situations provides temporary control. What you do in both those situations, those are biocidal type things. You kill everything in the soil. And for about one, two, maybe three years you can grow the crop. But this pathogen is also an excellent saprophyte, so it goes back into those soils. It recolonizes those soils to a greater extent than actually occurred beforehand. And then you've got a more serious problem afterwards than you had before. So those are only temporary solutions.

PLOETZGenetic modification, boy, that's a controversial thing. I've got some personal opinions on that. There has been a long history of traditional plant breeding, and Rob has alluded to this. Banana is a tough one to breed by conventional measures. And there are a lot of technical reasons for that. I won't go into them, but for about a hundred years, the first banana breeding program was down in the West Indies in 1922.

PLOETZAnd that program and every program since, one of its major focuses has been to breed a banana that is resistant to Panama Disease. And to a program, they have a failed. They have produced bananas that have resisted other diseases, and bananas that have resisted Panama Disease, but those bananas cannot be shipped. They can't be grown profitably. They don't taste the way Cavendish does. They've got problems, serious problems.

PLOETZSo long story short, breeding a resistant banana is going to be extremely difficult. Genetic modification by other means, I don't know if we want to go into that, but that's a possibility. I've got colleagues around the world, one in particular in Australia that has some very promising results there. But the question there is whether consumers are going to accept a GMO banana. And I hope that changes in the future. These technologies offer a lot to -- not only for producers of export bananas, but also hungry people in Africa, in Asia, in the Americas. But, again, consumer perceptions have got to change.

GJELTENWell, Randy, I wish you weren't so downbeat about this. I'd feel better if you were more optimistic about that.

PLOETZI'm realistic.

GJELTENAll right. Dan, I have a couple of interesting questions for you. This has to do with sort of the banana industry. Kim -- Kit, sorry, is wondering how long in advance of sales are bananas picked. And, you know, does that affect what kind of bananas are grown? Kathy, who sent us a comment via Facebook sort of has a similar question. She says, "We've been decimating the gene pool with our passion for creating the perfect shipping banana. To what extent -- you know, now that bananas are exported so much, to what extent is coming up with the perfect shipping banana actually sort of changed the way that bananas are grown or sort of the variety of bananas that are favored by banana producers?

KOEPPELSure. It's a huge problem. The global expansion of Cavendish for both export and also for factory plantations in Asia that serves city, which is a form of export, it's just by truck, has led to the loss of native and wild bananas. There's a real, real question about preservation of banana diversity. And of course we need those diverse bananas, not just for cultural reasons, but because we need the genetic material in them to experiment with and grow better varieties. Some of those may hold the keys to resistance. So the spread of Cavendish is kind of like the spread of McDonald's. The local mom and pop restaurants are gone.

KOEPPELAs far as shipping, a banana needs to reach a supermarket green and go to those brown spots in about seven days. And the trip from plantation to the ports in the U.S. is usually another seven days. So we're looking at bananas that are about two weeks old, and their ripening is controlled through use of various chemicals and controlled atmosphere and refrigeration.

GJELTENMm-hmm. Rob, I want you to answer. I think I know the answer to this question from Teresa, but it's one that probably is on the mind of more than a few listeners right now. And she's worried about bananas that reach customers coming from infected banana trees. If consumers are getting bananas from infected trees, would there be any danger from eating those bananas?

BERTRAMNo, none whatsoever.

GJELTENI didn't think so.

BERTRAMThis is not something that would threaten any animal. It doesn't even threaten other kinds of plants. But if I could add something here, Tom, we talked about the genetic base of bananas and the elimination of some of the local types. But there are still many wild bananas.

GJELTENRight.

BERTRAMAnd they actually reproduce by seed. Now, you don't want to eat one because if you bite a banana seed, you'll likely chip a tooth. They are that hard. But they -- in that material is a treasure trove of potential genetic diversity with which we may eventually do what Randy was saying we need to do, you know, find some kind of lasting defense against a disease like Panama Disease. But unfortunately the world's cultivated bananas, even beyond Cavendish, are from a very limited number of clonal groups. And when I say clonal, I mean it's because those kinds of bananas are vegetatively propagated, so they tend to be almost identical.

BERTRAMAnd so it's like going through a bottleneck, so there's a lot of genetic diversity in the wild still that we have not exploited, but with new tools and new scientific approaches, it's not beyond the realm of possible. And I think the other thing that I would like to put on the table, Feed the Future is looking very hard at trying to find places where public and private partnership could come together to solve problems that affect small holder farmers and poor people, but also the interests of a company serving a huge consumer market in the United States or elsewhere.

GJELTENInteresting. Let's go now to Troy who's on the line. He's been waiting a long time. From Phoenix, Ariz. Sorry you had to wait so long. Troy, this is your chance.

TROYOkay. Thank you, gentlemen. My call and concern was on the waste. I've been delivering bread to grocery stores in the Phoenix area for over a decade. And by far I believe bananas are the most thrown out food because they -- as soon as they go from a slight little bit of green, they bring pounds and pounds and pounds of them to the back. They put them in the compactor. They don't even donate them, because they say they're past their freshness. But if we may be slowed down the import, that was another thing, the fact that they were -- at the beginning, you said they were the most (word?) fruit, is that they stop the import numbers or some kind of holding, because it is by far, again, the most wasted food in this area that I've seen over ten years.

GJELTENWell, Dan, you've been making a point that consumers are really picky about the bananas they buy, right, and once they get a couple of black spots on the banana, they may not want it.

KOEPPELYeah, and it's interesting, you know, some of your listeners might've seen these so-called baby bananas, which are mini bananas, in the supermarket. Chiquita and Dole have tried to introduce those, but they've largely failed. And the reason is that those bananas taste better when they've got more black spots. And we've been so conditioned to throwing that banana away that people eat them too soon and they say, oh, these don't taste very good, I don't want them.

KOEPPELSo part of the issue of introducing a new banana would actually be to teach people about different ripening characteristics. Some bananas taste better when they're still a little green. Some have to be very black. And the banana industry has done such an amazing job of teaching us what a perfect banana is that we throw ones away that seem imperfect, even if they're really good.

GJELTENI got a question here for you, Rob. This is from an email from Kerry. "To what extent are the epidemics in Cavendish caused by mono-cropping and lack of bio diversification?" And the reason Kerry raises this is that he's wondering about whether there is any similar risk for corn production in the United States as a result of the lack of bio diversification.

BERTRAMSo let's unpack that, Tom. It's really two questions. One is about mono-cropping and the other one is about narrow genetic diversity. Mono-cropping in and of itself is not necessarily going to lead to a disease -- a breakdown in resistance. And we have many examples of that, including the emailer mentioned corn. And corn is very efficiently grown as a mono-crop. The issue of a narrow genetic base is a different issue, because in many kinds of crops, what we try to do is deploy -- scientists work to deploy different kinds of resistance so that we don't get genetic vulnerability.

BERTRAMThe United States corn belt was -- or the southern part of the United States was greatly affected about 35 years ago by a blight that raced through a huge number of corn varieties, because they all had the same type of susceptibility, even though they were different. So the caller's correct about needing strategies. The problem is that in banana, it's not easy to implement those kinds of strategies because they're not easy to breed.

GJELTENRight. Rob Bertram is chief scientist at USAID's Bureau for Food Security. I'm Tom Gjelten. This is "The Diane Rehm Show." And we have -- not surprisingly to me, because I know GMO issues are really big for our audience, we have a number of questions about genetic modification. And let's go to Ian, for example, from Houston, Texas. And, Ian, I believe you have a question about GMO modification.

IANYes. Hi. Can you hear me?

GJELTENYep. Go ahead. You're on the air.

IANHi. I had read an article in Nature about a team in Korea working on...

GJELTENA team in Korea.

IAN...a solution to this issue. Yes. They're working with CRISPR. It's a new emerging targeted genome editing technology. And they've actually developed a way to knock out a receptor in the plant that's allowing this toxin from the Panama Disease fungus to be taken up into the plant cells. And they've -- the novel thing about this CRISPR platform is that allows them to modify the genome of the organism and then remove all of the foreign DNA from the plant, so it actually skirts all GMO regulations. So...

GJELTENAre you familiar with that...

IAN...(unintelligible) actually market it...

GJELTENYeah, let's put that question to Randy. Are you familiar with that technology, Randy?

PLOETZYeah, it's a relatively new, powerful technique for editing genomes. And it's being used in a lot of different plants. Yeah, so I am aware of it. And it's -- again, this is all genetic modification, if you consider, oh, geez, you're inserting foreign genes from jellyfish or whatever. That's not the case. There are so many other technologies that allow precise modification that would not raise the concerns of anybody who -- even people who are concerned about GMO. So, yes, CRISPR is one of many different things.

PLOETZAnd as long as we're talking about GM plants, I should mention there was talk about loss of diversity in banana. My colleague in Australia actually has inserted a gene from a wild banana into Cavendish, and it's one of his best GM bananas. So diversity of bananas for sources of genetic resistance to pests and diseases, that something else that needs to be considered.

GJELTENWell, Rob, you're nodding your head. I know from even having hosted this show a few times that genetically modified foods are a big sensitive issue for a lot of consumers, and yet, you know, this example suggests that there may be a real helpful role here for them, for genetic modification.

BERTRAMThat's right, Tom. Especially in a crop like banana which is so difficult to breed. Some of these techniques that have just been mentioned hold the promise of being able to deal with problems that have been intractable through breeding, like fusarium disease resistance, or bring in new characteristics as an example from the wild genome. In Feed the Future, we're actually working on a solution to bacterial wilt in partnership with African scientists.

BERTRAMWhile these are emerging technologies, and they are to some degree controversial, our approach on this is we're demand-driven. There are some times when if you don't use these kinds of technologies, you can't solve the problem. And we not only collaborate together on a research project, we also help build the scientific regulatory capacity building of our partner countries, so they make the choices as to their farming communities, their consumer groups. They make the choices. But certainly there are -- banana, cassava, a number of these colony propagated crops, these kinds of technologies can be very attractive.

GJELTENDan, I'm going to give you the last word. You're Mr. Banana here this morning. How concerned are you for the future of the banana right now, at least for us here in the United States?

KOEPPELYou know, it'd be foolish for me to say that I don't agree with almost everything that's been said here, and the deep concern, but I am also optimistic. There are -- Cavendish is not a very good tasting banana. And I think that's the key. Americans have shown an interest in better tasting citrus, better tasting apples. And I believe that banana diversity is the answer, that the banana industry is going to need to work very hard to bring multiple kinds of bananas, including a replacement for Cavendish in the commodity sector.

KOEPPELBut ultimately consumers will respond to that. I believe they will pay more for great bananas. And I would like to see a world where we get as many bananas as we do apples, and they're all absolutely delicious, and there's more profits in the industry.

GJELTENWell, that's Dan Koeppel. He's the author of "Banana: The Fate of the Fruit That Changed the World." And it's nice to end this discussion on a relatively positive note because there have been some alarming facts raised for those of us who care about our bananas. My other two guests were Rob Bertram, he's chief scientist at USAID's Bureau for Food Security, and Randy Ploetz, who is a plant pathologist at the University of Florida. Thank you guys for joining our discussion. Good to see you.

PLOETZYou bet.

BERTRAMThank you, Tom.

KOEPPELThanks so much.

GJELTENAnd thanks to all our listeners who called in with questions. This is "The Diane Rehm Show." I'm Tom Gjelten.