TRANSCRIPT Chocpocalypse Now! Quarantine and the Future of Food

This is a transcript of the Gastropod episode, Chocpocalypse Now! Quarantine and the Future of Food, first released on June 22, 2021. It is provided as a courtesy and may contain errors.

CYNTHIA GRABER: Well, so I am going to ask the easiest question first, which is if you could both say your name, how you’d like to be identified and the name of your book.

NICOLA TWILLEY: Well, Cynthia, just to remind you.

GRABER: LAUGH I’m not sure what your name is. So, please, let me know.

TWILLEY: In case you’ve forgotten, I’m Nicola Twilley. You call me Nicky. In your more polite moments. And I am co-host of Gastropod. It’s an award winning and popular podcast about the history and science of food.

GRABER: Thank you for putting that right up front. I appreciate it.

TWILLEY: And I am coauthor of a brand new book called Until Proven Safe The History ofThe History and Future of Quarantine. And I do know the subtitle of my own book.

GRABER: Wow, even you didn’t get the subtitle of your own book.

TWILLEY: I know it! I just slipped up halfway through.


GRABER: Geoff?

MANAUGH: And I am Geoff Manaugh. I am Nicky’s husband and I am the coauthor of Until Proven Safe: The History and Future of Quarantine.

GRABER: This, as you might have been able to tell—this is kind of an unusual show for us, because we have a bit of a role reversal issue going on. I was the one and only interviewer—

TWILLEY: And I was getting interviewed! Along with Geoff, who, as he says, is my husband as well as my co-author. He normally has more of a backstage support role here at Gastropod.

GRABER: And you are not normally in the interviewee hot seat.

TWILLEY: Being grilled! Grilled alive!

GRABER: Gastropod-style. Yes, of course, we both are Gastropod, the podcast that looks at food through the lens of science and history, I’m Cynthia Graber—

TWILLEY: And I am Nicola Twilley, and this episode is all about quarantine!

GRABER: Not the one we just went through, although that’s obviously in the book, too—this episode is all about the quarantine we put our food through. Why in the world would food ever get stuck in quarantine? What are we protecting it from?

TWILLEY: One word, many syllables: chocpocalypse. And, you know, economic disaster, famine, ecological collapse, all the good stuff.

GRABER: We’ve got it all coming up on Gastropod, but we promise it is not all depressing!

TWILLEY: No indeed. We get naked, we—

GRABER: At least you and Geoff, luckily—

TWILLEY: Right, we hang out with billions of bees, and we take a trip to a robot-protected island off Australia. It’s all in chapter 6 of Until Proven Safe, which you can pre-order now! And here’s the sales pitch for doing just that: You might think, hey, I like the sound of this book, but I’ll wait ‘til it’s out on July 20th to pick up my copy. But—and this is something I’m only now learning because this is my first book—pre-orders are like gold dust! They make a huge, huge difference to whether a book succeeds or not. So if you think you might buy it, order now! Or, you know, at the end of this episode!

GRABER: We even unsurprisingly have a link on our website,


GRABER: So, Nicky, I have been hearing about this quarantine book for many years—

TWILLEY: Many, many years, because our publisher has been waiting for it for many, many years!

GRABER: And certainly I never thought I’d have any personal experience with the topic. But I did always wonder, and I saved up the question just for this episode: Where did you both get the idea for a book about quarantine?

TWILLEY: Let’s go back a long, long long time ago.

MANAUGH: You know, we are married and we were on a trip together in Australia, our first time there together, staying in Sydney. And at one point a local friend invited us out to a picnic and it was out on a peninsula on the other side of the bay from Sydney proper. And it was right by what is now a hotel. It’s called Q Station, and it was a quarantine station.

TWILLEY: But, as Geoff said, now it’s a hotel! That remote oceanfront location that made it great for quarantining passengers traveling to Australia by boat in the 1800s—turns out to be delightful for people looking to get away from it all today.

GRABER: And that’s not uncommon for sites that were used for quarantines in the past.

MANAUGH: You know, when you hear about a quarantine station, they tend to be ruins. They tend to have been turned into something else. Maybe they’ve been eliminated entirely, you know, torn down or razed. As if quarantine was this obsolete strange thing that we don’t do anymore. And so, somewhat ironically, given how the book turned out, you know, our initial question was really kind of asking, what was quarantine? You know, why did we do it? Where did it go and why has it gone away?

TWILLEY: You have to remember this was many years pre-COVID. But once we began looking, we realized that actually, quarantine hadn’t gone anywhere.

MANAUGH: And so, in fact, you know, as we really kind of started pulling on the strings of quarantine, we started seeing it everywhere. You know, it’s all over the world. It was happening at various scales. It was happening in agriculture. It was happening with human diseases like Ebola and COVID-19. But it was also even happening in things like on an interplanetary scale with talking to people who worked at NASA and the European Space Agency in terms of how they quarantine, how they help prevent the contamination of Earth from off-world microorganisms, or how they prevent, you know, how they help protect places like the moon and Mars from bringing earthly microbes to them. And so, yeah, it was a huge topic. And it really just seemed like the kind of thing that a book would be a lot of fun to do. And so we sort of dived into this thing. I mean, that trip to Australia was in 2009!

GRABER: LAUGHS That was a little while ago

MANAUGH: And not only are we still married, but the book is finally coming out.

TWILLEY: Did I mention? July 20! Available for pre-order right now!

GRABER: You did. And we’ll probably end up saying it again before the end of the show. So we throw around the word quarantine a lot, especially these days. We’ve been talking a lot about it in the past year. But how about, like a real definition? What exactly is quarantine?

TWILLEY: A true quarantine is when you don’t know if something or someone is carrying a disease or not. You don’t know if they’re a danger. You don’t know if they’re dangerous, but you do know that they might be. They pose a risk somehow. And so what you do is you wait. You wait to see if that disease shows itself and you wait to see if that person or that thing is safe or not.

GRABER: The idea of quarantine is to create a buffer, a window of time to see if there’s a problem. Is something safe, or healthy? No way to know until we wait. In the past, that wait time might have been forty days, this year it’s been two weeks for COVID.

TWILLEY: When quarantine was first invented, in the 1300s, in the Adriatic, because the Black Death had arrived in Europe, it got its name because people chose forty days as the length of time to wait. It was a quarantena. And they picked forty because of the religious connotations. Forty was a symbolic number.

GRABER: The ancient Israelites wandered in the desert for forty years, there were forty days and forty nights that the skies opened up and caused the flood that sent Noah floating with all those animals on his ark. What I learned in Hebrew School as a kid was that forty kind of represented a long time, even a new generation.

TWILLEY: But nowadays, we set our quarantine time based on science—on how long whatever disease we’re worried about takes to emerge.

GRABER: The key is that quarantine doesn’t last forever. Quarantine is always finite, isolation can be forever.

TWILLEY: When we were writing the book, people would always say to us, oh, like Typhoid Mary, that’s a famous quarantine. And we would have to say: No. We knew that Typhoid Mary had typhoid. The way she was treated was terrible, but she was being isolated, not quarantined. But, that said, you know, even within the field, people refer to quarantine and isolation interchangeably. And even in our own book, we’re not as rigorous as all that. We have an entire chapter on how nuclear waste is isolated. That’s isolation. We know nuclear waste is dangerous. It’s not being quarantined. So we’re not pedants. We’re flexible.

GRABER: So I have to say, Nicky, usually when we interview somebody about a book on Gastropod, we often have to figure out how to cover the entire book or like which parts of the book. And you made this really easy because you only have one chapter on agriculture. So thank you both very much.

TWILLEY: I had you in mind the whole time, Cynthia.

GRABER: Awesome. It also gives listeners a lot more to read.

TWILLEY: Yes indeed. Buy the book and you’ll get all the rest—the stories of how quarantine shaped borders, led to the invention of the passport, and was used to lock up loose women, what went wrong during COVID—even how we quarantine planets.

GRABER: In the part of your book that focuses on food and crop quarantine, you visit a quarantine station on the California border with Arizona, it’s called the Needles Inspection Station.


MITCH VEGA: How you doing, bud? Good. This is his bills and all this is on here. They usually just have basic stuff. Auto parts. Yeah, nothing that concerns us. Have a good day, bud.

TWILLEY: This is Mitch Vega—he’s getting the documents that say what the 18-wheeler in front of us is carrying. Needles is on the I-40, which is one of the big cross-country freeways coming into California. Every truck that comes into California on I-40, Mitch or one of his colleagues stops it.

VEGA: How you doing sir? Hazardous materials. Loads. Scotch tissue. Supply solutions. He’s good. Mars Chocolate.

TWILLEY: We should hijack that one.

VEGA: We got a lot of chocolate that comes through here.

GRABER: The site is is out in the desert, there isn’t much around, and it’s called Needles because that’s the name of a nearby city.

MANAUGH: It’s basically a kind of a checkpoint that you would drive through on your way from Arizona into California. It’s four lanes. There’s generally about six people working there.

TWILLEY: Basically, it’s a border control station run by the California Department of Agriculture. And they have one mission and one mission only, which is to intercept any plant diseases or pests that might be kind of hitchhiking their way into California from anywhere else and that might pose a threat to the California agricultural industry.

GRABER: Michele Jacobsen is in charge of the Needles Inspection Station.

MICHELE JACOBSEN: We have a lot of produce comes through. Anything. Citrus, your winter greens, kiwis coming in right now out of Italy. Sometimes South African oranges. Chile, a lot of stuff comes in through here from Chile, too. What they’re doing is the inspectors are checking the bills of lading. So when the drivers pull up, they know that they have to give us our paperwork and we see what’s going on.

TWILLEY: Depending on what’s in the truck, Mitch and his colleagues might just wave the driver onward—like the Mars chocolate, or the auto parts. But if they’re carrying produce, then it may well be subject to a quarantine order.

JACOBSEN: What’s not under quarantine is easier to tell you than what’s under quarantine. What’s not under quarantine is a lot of your lettuces, your tomatoes are not under quarantine, your melons are not really under quarantine. Bananas, there’s no quarantine on bananas. Onions and stuff don’t have quarantines. But there’s a lot of quarantines. It’s easier to tell you what’s not under quarantine.

TWILLEY: We were at the Needles checkpoint on one of the busiest days of their entire year—it was the peak of bee season, when trucks full of bees from all over the U.S. are flowing into California to pollinate all the almond trees. 75 billion bees to be precise. Every single truckload gets inspected. The ones that are pest-free get waved on. Geoff and I suited up in bee suits and Michele took us out to see some of the rejected bee trucks.

JACOBSEN: What we’re doing over here is all these loads have been rejected for having pests on them. And it could be anything from a small hive beetle to any kind of an ant, it could be a fire ant. It could be a carpenter ant. And or anything that would be considered as a Q rating, which is something that is not determined to be established in California.

GRABER: Michele and her team are scouring the trucks they stop. They’re searching for all kinds of tiny pests that haven’t yet gotten into California, these Q-rated ones—and those are different kinds of beetles, ants, moths, flies. Because California is really concerned about what these creatures might do if they penetrate its borders.

TWILLEY: Well California is, as my garden is evidence, the fruit and vegetable capital of America. I mean, the agricultural industry here is massive. I think the latest estimate was that it’s worth fifty billion dollars a year. Two thirds of America’s fruits and nuts are produced in California was the stat that blew me away. And of that, it’s 100 percent of all the almonds—all the almonds! All the almonds that are eaten in America and 80 percent of all the almonds that are eaten in all the world.

MANAUGH: You know, California is sort of two things at once. It’s very, very geographically isolated in the sense that it is surrounded by mountains, deserts and the Pacific Ocean. And so it’s kind of its own little unusual ecosystem. You know, species that have been here have been here for a very long time and species that have not been here have been, you know, separated by these natural barriers that exist. And so when newly introduced species do come here, they often find they have no natural predators.

GRABER: Michele and her team become the predators—they look to see if there are any bugs—and then they have to figure out if the bug is anything to be worried about.

TWILLEY: What’s going on here?

JACOBSEN: He’s checking under the microscope for a pest. He probably—did you find those on the bees, Matthew?


JACOBSEN: So he found something on the bees and he’s checking it. That’s our digital imaging microscope. So he is taking a digital image and he’s sending it down to our pest diagnostics lab. And they will send us back an email telling us what the insect is rated. And then we go from there.

TWILLEY: The pest diagnostics lab folks were actually on their lunch break, but as soon Michele and her team were able to confirm the bug’s ID, then they would know whether they could let the truck full of bees through, or whether it had to be turned back to be disinfested—usually by pressure washing—and then reinspected. Sometimes the entire load has to be destroyed—not bees, they would just get turned away, but if it’s a load of infested oranges, that’s likely going straight in the incinerator.

GRABER: Infested oranges—that’s a huge problem. In our citrus episode, we talked about how the Asian citrus psyllid is a massive issue because the little bug carries a bacterial disease that can completely destroy citrus crops. And California’s citrus industry is valued at billions of dollars.

MANAUGH: Oh, yeah. I mean, that’s part of the stress. And, you know, kind of the existential stakes actually, of the problem here is that you’re dealing with unbelievably tiny little offenders, you know, things that are the size of a grain of rice or just an egg that might be the size of like a mustard seed.

TWILLEY: Michele told us that one of her proudest moments was stopping this tiny citrus psyllid at the border.

MANAUGH: Someone was moving across the country. They looked into their moving van and they had an entire tree back there. The tree itself did not look very healthy. You know, that was obviously a warning flag for them. They inspected that tree and that’s when they found the citrus psyllid. And that, of course, is not something they want to let into California. It’s found very fertile ground in Florida already. And it’s actually wiped out an estimated five out of every seven Florida growers. It’s a huge threat. And it’s people like Michele Jacobson that are keeping it out of California.

GRABER: But like we said, the psyllid is the size of a grain of rice. How did they even think to look to find it in a moving van—I mean, that’s not a truck carrying one of the crops of particular concern!

TWILLEY: I know! In a way it was just lucky—they also do random inspections, especially of cars and RVs with out-of-state plates and they happened to find it. But they do also have a logic to what they decide to inspect beyond just those trucks carrying crops that are on the quarantine list.

MANAUGH: The way Michele, who runs the station, described it to us, was basically “thinking like a pest.” Trying to imagine where, if you’re a pest, if you’re a bug, if you’re a little insect, where you would be in a container, in a truck bed, or maybe even just like a set of somebody’s backyard patio furniture that they’re bringing across the country to their new home in California. And so then that’s where they’ll look. So they’ll think to themselves, OK, here’s a nice little crack that this bug might lay some eggs here or here’s a dark little corner where we might find something. And so that’s where they look. And that’s actually, it turns out, how they have found a lot of things.

GRABER: Do people try to sneak through things that they would want to inspect, like trees from their house or their moving pods or anything, are they trying to get things through the border?

TWILLEY: Yeah, all the time. And a lot of times people don’t necessarily know. So one of the things Michele said was that people who live in their RVs and just kind of tool around, oftentimes they’ll have a little like potted plant that they like to put out when they’re actually kind of stationary somewhere and those can carry pests. She said, actually, one of the things she’s seen is there’s a huge rise in chainsaw art.


TWILLEY: Yeah, not a thing that I’ve dabbled in myself.

GRABER: I’m not sure what that is.

TWILLEY: I guess people take chainsaws and carve tree trunks and oftentimes, you know, they’ll be like a little hole in the tree trunk. She’s like, Oh, it’s so beautiful. And then I look and there’s a hole and there’ll be a bug inside that hole.

GRABER: Oh my god.

TWILLEY: So she has a huge problem there. Some people lie. She pulled over a guy who had a bag of pecans, which are a Q-rated nut, and she said she was going to have to confiscate them and he said no and turned around and went back into Arizona, came back an hour later. The pecans were in his suitcase. Apparently he forgot.

GRABER: LAUGHS. Forgot in quotes.

TWILLEY: Exactly. And then the other thing that’s really funny is like so many people are afraid of being caught with something that the entire freeway just before the checkpoint is just littered with people’s fruit and vegetables. So people throw out their baby carrots, which they could totally bring through. Baby carrots aren’t Q-rated. You know, people throw out their bananas. Not a problem. Again, there are, you know, no bananas to kill in California. So some people are so worried about being caught with something, which, of course, nothing happens. They either just take it away or clean it, but people see a checkpoint and panic. So.

GRABER: Of course Michele and her team can’t check everything that comes through. They just can’t. They do check all the trucks that are carrying crops that are known to harbor pests, but even there, they can’t go over every inch. Traffic would be backed up for miles. So sometimes things do get through.

TWILLEY: An amazing example is the bee example. There’s this incredibly disastrous bee mite that has been responsible for a lot of the colony collapse stuff you see. We talked about it in our honey episode. And this mite used to be a Q-rated pest. They used to inspect for it. Back in the 80s and 90s, they were inspecting for it. Eventually it got through. Now it’s established. But that bought the time for them to start working on which chemicals can you spray your hive with to kill this mite. Those chemicals also have problems. So at the same time, they’ve been working on breeding something called a hygienic bee, which is resistant to the mite. So quarantine like: yes, kind of it failed in the sense of like now this mite is established in California, but it didn’t fail in the sense that it bought more than a decade for people to figure out how to mitigate the consequences of the mite arriving, as it were.

MANAUGH: And I think that that’s one of the things that happens, that even though things get through, you know, even though the quarantine is not total and it’s not universally successful, what it does do is it gives us time to get ready for this thing to show up. And so what I mean by that is developing things like responses, treatments, even new pesticides. You know, getting people ready, maybe they have to plant new crops. Maybe they actually do need to physically design something into their existing farms or greenhouse operations to help filter out this thing that’s coming. But quarantine is really vital then in the sense that even though it’s not perfect, it allows us to get ready.

TWILLEY: Quarantine for plants does this, and so does quarantine for humans. You heard the expression flatten the curve everywhere in spring 2020—that was coined by the head of quarantine at the CDC, which is a story we tell in the book. He analyzed the 1918 flu and he realized the cities that did best used quarantine to buy themselves time—quarantine flattened that curve so doctors and hospitals could prepare to handle the disease. Same with the social distancing and so on of COVID. The point was to give us time to get ready and to come up with treatments and even vaccines.

GRABER: But one thing that did occur to me as I was reading about Needles Station is that it’s not actually a real quarantine.

TWILLEY: Yeah, you’re totally right. You called it, Cynthia. LAUGHS. The Needles border inspection station is not true quarantine, even by our own definition. But there is—you know, honestly, mostly for plants, there isn’t such a thing as true quarantine because, you know, unlike people, plants are sort of not that valuable individually. And if you put it in the incinerator, you know, it’s okay.

GRABER: Imagine an orange—whether it’s the fruit or the tree, it’s just not worth putting in quarantine to see if it gets sick. If you notice a problem, a bug of concern in the truck, or a sick plant, you might dump the whole truckload of crops or plants in the incinerator, frankly. It’s cheaper to replace oranges than have a special quarantine facility to hold them. But some individual plants are indeed worth saving.

TWILLEY: And cacao is one of those plants. So we actually went and visited the International Cocoa Quarantine Center. It is in a small commuter town outside of London, bizarrely enough. Just a greenhouse. I mean, it’s a big greenhouse, it’s the size of an Olympic swimming pool, like a 20 minute-train ride from London.

GRABER: This one greenhouse is tasked with saving the world’s chocolate. Coming up after this break.


GRABER: So cacao trees, or you know the trees that grow the precious beans we turn into chocolate, their facility? That’s a real plant quarantine. Because each of the cacao plants that’s being moved around the world is super valuable.

MANAUGH: You know, it’s a massively loved global commodity. The size of the industry is truly huge and intercontinental. And so you have a lot to protect. And so quarantine, in this case, is actually worth the cost and it’s worth the kind of logistical complexity of making sure that it happens. And then on top of that, because of the way that the cacao economy, I guess you could say, kind of works, is that researchers and agronomists and people who are, you know, working in chocolate basically are always moving these bits of budwood around for agricultural reasons.

TWILLEY: Basically, chocolate is a much more lucrative crop than oranges or even avocados. And, in order to work on cacao breeding and pest resistance, researchers have to move plants around between the world’s major chocolate growing regions. And every single cacao plant that needs to travel—it has to make a stop in Reading, England.

MANAUGH: And then on top of it, you know, it’s also the diseases that strike the plants are very quarantinable in the sense that they fit perfectly into this little model that we’ve been talking about, which is that you can have an infected plant, but it doesn’t show symptoms until a certain amount of time has passed. And so you have to wait, by definition, to see if sickness emerges and to see if this disease reveals itself. And so, you know, that’s part of like the title of our book. We have to wait until it is has been proven safe.

TWILLEY: Like a lot of diseases you can see immediately. And then why would you quarantine, you know? But with some of the diseases—and this is the other problem with cacao is that it is vulnerable to a lot of diseases. And they all have amazing names like frosty pod, witches’ broom, swollen shoot virus, vascular streak dieback. The researcher there just read out this long list of terrible sounding ways for a cacao plant to die. But the problem is you won’t know if it has one of those diseases for several months. And that’s the whole purpose of quarantine, is to kind of—that waiting buffer, to see.

GRABER: So one thing that does seem really bizarre, probably not just to me, but to everybody else, too, is that England is not known for being a cacao growing country. How do you grow cacao there? Why would you grow cacao there?

TWILLEY: Right. It’s yeah. You know, cacao does like it wet, which we do have in England. That is definitely part of the famous British weather. But it also likes it quite hot. And so there’s a logic there. Basically cacao pests are not going to pose any threat to anything in England because they won’t survive. They are only suited to, you know, a tropical environment. And so you can put these cacao plants in England almost without any fear.

GRABER: Even if by some accident the cacao disease gets out of the quarantine facility, there are no cacao trees in the UK that those diseases could make sick. And frosty pod and witch’s broom only infect trees in tropical regions in general, so they really can’t do any harm in England. On the flip side, there’s nothing in the UK that could make a cacao tree sick, cacao diseases just don’t grow there. Because cacao trees and their diseases like it hot.

TWILLEY: If the temperature in the greenhouse drops to 53 degrees or lower for more than a single minute or two, the cacao plants will all die.


TWILLEY: So they have this high tech kind of automated system. It’s all computer controlled. There are screens creating the right amount of shade to mimic the tropical understory. And, you know, obviously heaters. It’s all super high tech. But, yeah, if it goes out, Paul Hadley has like an alert on his phone and he can monitor it. And he did say, more than anything, that’s the thing that keeps him up at night.

GRABER: Paul is the guy in charge of the International Cocoa Quarantine Center in Reading, he is the man in charge of defending the world’s chocolate against disease—and I hope he is well protected against disease because I don’t think I could live in a world without chocolate! But so walk me through the quarantine process there.

TWILLEY: Cacao plants travel as budwood is what I learned. So that’s just basically a piece of branch with a bud on it. And they show up. And Paul Hadley, will graft that bud onto what they call a mother plant and an indicator plant. So the mother plant just sits there and worries for the next three years, in true motherly fashion. And the indicator plant is a species of cacao that is chosen specifically because it shows diseases really well, like it just gets visibly sick when it’s infected. And so the mothers sit around the edge of the greenhouse kind of watching and the indicator plants sit in the middle waiting to see if they develop a disease or not. But it takes two years to be sure. Then if the indicator plant has no disease, then they can harvest some more budwood from the mother and send it on. And if the indicator plant shows disease, then, you know, it’s toast. The whole thing goes in the incinerator.

GRABER: There are a handful of facilities like this in cold countries—they’re called climatic quarantine, because scientists use the climate as a layer of protection—and they’re used to quarantine and test and ensure the safety of tropical crops like rubber and bananas and coffee.

TWILLEY: Thankfully. Half our book—the half I wrote—that was brought to you by chocolate. But the other half was entirely dependent on caffeine.

MANAUGH: Coffee is embarrassingly important to me. It’s, I think, like half of my brain is probably fueled by caffeine. So a coffee free world would be quite catastrophic in my opinion. Far, far scarier than a world without chocolate.

GRABER: We will have to agree to disagree on this one. But while chocolate and coffee are super valuable, they’re kind of a luxury, we won’t starve without them. Even citrus— which I do love, and I don’t want to imagine a world without it—the harm would be more of an economic one than a world hunger one.

TWILLEY: But, actually, our staple crops are vulnerable too. 15 crops provide 90 percent of the world’s food. And they get attacked by pests and diseases too. In fact, we’ve made them really vulnerable by growing them in such huge monocultures. If a disease came along and wiped out wheat—then there really would be hunger.

MANAUGH: The example that’s given a lot is wheat rust. There was a particularly virulent example of it in Uganda in 1999, which resulted in the name UG99 or perhaps U-G-99, depending on how you want to say it. I say UG99, it’s an uglier word, so it maybe communicates some of the problem. But so UG99 can actually take these plants and blacken them on the stalk and take a otherwise beautiful, picturesque field of golden plants and turn them into these kinds of blackened, horrible looking, broken stems.

TWILLEY: UG99 actually was so virulent—normal wheat rust is, you know, a well-known pathogen that often reduces yields by half. UG99 reduced them by 80 percent or more.

GRABER: Luckily we do still have wheat, so UG99—or really any variant of wheat rust—it hasn’t yet totally wiped out wheat yields. But wheat rust has had a really serious impact for millennia.

TWILLEY: Yeah. So it has been an enemy of ours since we’ve had wheat, which is obviously many thousands of years at this point. One of the things that I thought was amazing is that the ancient Romans had a specific kind of god of rust and would—on his annual festival day on April 25th, would sacrifice rust colored animals. So like foxes, I guess, you know, reddish brown animals, squirrels maybe, who knows, to Robigo and sort of beg him to not strike down their harvest. Apparently, it also didn’t work because rust is thought to have been one of the contributions to the fall of the Roman Empire. There were a few really terrible wheat harvests in a row that people, archeologists, think were due to rust.

GRABER: The disease has continued to be a problem since the ancient Romans. But then in the mid-1900s, scientists bred a bunch of different traits into wheat to help protect it from rust, so that’s helped. But then people kind of ignored the problem, and rust started to evolve and become a threat again. That’s why scientists at the USDA’s cereal disease lab in St. Paul, Minnesota, are now working hard to protect wheat from rust.

TWILLEY: They do all kinds of rust surveillance. They have this super facility for researching the biology of rust and for developing treatments for rust and, you know, for genotyping different rust strains and breeding rust resistant strains and all sorts of things like that. So that’s where we visited.

GRABER: But when scientists are worried about a microscopic airborne fungus that can just blow around in the breeze, they are pretty strict about making sure that nothing gets in or out.

MANAUGH: We had to take all of our clothes off and shower and then put on Tyvek suits and specifically Crocs. It turns out that Crocs are, I guess, are sort of an unexpected boon to the quarantine industry because they’re very, very easy to disinfect. And so, you know, Crocs are the kind of footwear du jour of biosecurity researchers. But in any case.


MANAUGH: So, yes,

TWILLEY: Stylish *and* practical.

GRABER: I know. Huh.

MANAUGH: But so naked beneath Tyvek…

GRABER: Naked, Tyveks, and Crocs.

MANAUGH: We were able to—anything that we brought in would have to stay in. And so we were told, you know, don’t bring your top secret research journal or don’t bring anything that you don’t want to see come out through an autoclave.

GRABER: If you haven’t spent a lot of time in a science lab, an autoclave is a machine that’s basically a super-duper sterilizer using high temperatures and steam and pressure. Inside it would be kind of like an instant pot on steroids—it cooks and kills the microbes.

TWILLEY: Right. Like, I was like, I have to take off my bra, too? And she was like, I mean, unless you want it destroyed on the way out., yes. Take off your bra.


MANAUGH: But that also meant that the paper that we took notes on—and paper, ironically, being very heavily textured and full of little nooks and crannies, you know, is actually quite a threat in these kinds of scenarios because they can hook, you know, germs or seeds or whatever it might be, you know, so paper is considered susceptible matter in quarantine terms. But so we could take notes. But then what was interesting is that they then scanned our notes, emailed the JPEG to us or the PDF and then burned the documents. So it was an interesting experience of just going into a place that basically nothing comes out of. It’s a kind of a quarantine black hole.

TWILLEY: And they only do research on UG99, this super rust, actually during the winter. So even though this facility is like ultra high tech, you know, triple glazed, the air handling is completely designed so that not a molecule of air, you know, ever comes in or goes out without going through trillions of filters. Even despite all of that, they like to have the extra security blanket of a layer of snow outside so that if any of this UG99 rust gets out, it’s just going to die because it’s so fricking cold in Minnesota.

MANAUGH: There was one detail that I thought was really interesting, which was that one of the risks of breaking quarantine would actually come from the proximity of this building to the athletic fields. And the woman mentioned the threat of the building getting hit by a javelin from the track and field team, which I just thought was an interesting way to imagine the beginning of the wheat rust apocalypse in North America.

GRABER: This is all fascinating, but of course it’s also all a little scary. Wheat rust, the chocpocalypse—but there are solutions, coming up after the break.


GRABER: If you had to rate how well all these measures are doing when it comes to protecting our food supply, what grade would you give them? Or is this all just kind of tilting at windmills, given the scale and scope of the problem? Is it helping? Is it buying us time to develop solutions? What’s going on?

MANAUGH: I mean, I definitely do think that it’s kind of tilting at windmills in the sense that you have an absolutely massive problem. It never goes away. It’s 24 hours a day. You know, it’s every boat that’s crossing an ocean right now, every plane that’s in the air, every truck driving across the border into California. You know, all of these things are risks. There are some really interesting solutions that have been tried or at the very least, you know, attempts to mitigate this. One thing that I really, you know, I was excited to read about are sentinel plots. So sentinel plots are plots of land, often down near the US-Mexico border, but also sort of scattered throughout the country’s agricultural regions. And sometimes those plots can just be a couple rows of plants. But those plants are used almost like photographic developing tools, so they’re there to see if they catch a disease or if they exhibit symptoms of an infection or of an infestation. And so they’re really quite useful, in that all you have to do is go out and check them and see if something’s happening. And then you’ll know right away like the entire field or maybe the entire region is at risk. But unfortunately, you know, they’re a successful and quite useful strategy, but they’re very underfunded. And so I would love to see that kind of thing pick up and find the proper funding.

TWILLEY: I mean, I think it’s, again, like we’ve seen with COVID, it just doesn’t seem like the most pressing priority often. You know, these sentinel plots, they seem cheap and easy, but you have to pay a farmer to sort of not grow crops, their own crops, on this particular two rows of the field. And you have to pay them to go out and check it. And it’s a minuscule amount compared to the damage that would happen if the pathogen did make it here. But investing in those kinds of preventative things is just not something that we in the U.S. or even globally in general are very good at.

GRABER: Until there’s a need, until the problem strikes.

TWILLEY: Until it’s too late.

GRABER: So far, so depressing. But as it turns out, some people are developing solutions that can protect our food supply—and some of the best ideas are, strangely enough, coming from an uninhabited nature reserve, it’s a small island off the coast of Australia.



NARRATOR: Since 1910, Barrow Island has been a Class A nature reserve, managed for the conservation of flora and fauna.

HARRY BUTLER: Barrow is not only an exciting place, it’s probably one of the few places in the world you can say is unique. So it’s quite a naturalist’s paradise in terms of what Australia used to be like before it was disrupted by the invasion of us modern Australians.

NARRATOR: That is why a major focus of operations on the island has been quarantine management.

MANAUGH: So Barrow Island off the coast of Australia is a really fascinating place to study from a quarantine point of view. It’s being funded and operated by Chevron, the energy giant. And it is basically an attempt to keep any invasive species off of Barrow Island.

GRABER: In fact, that promo movie you heard from was actually made by Chevron. And Chevron is there because of what is underneath the island—there’s one of the world’s largest reserves of natural gas. And it had been completely untapped.

MANAUGH: Chevron was not able to obtain any sort of right to drill or extract natural gas, which is what Barrow Island is very rich in, unless they instituted this unbelievably complex quarantine procedure, the idea being that they have to keep the island as pristine as it was when they got there.

TWILLEY: Of course, you could argue that by taking the natural gas out of the ground and hastening climate change, that they are, in fact, contributing to the ultimate downfall of the island. But let’s leave that aside for now.

GRABER: LAUGHS. Yes, for the moment at least. But so then how did they prove that they were actually going to keep it so pristine? And how did they kind of enact their program? What did they do?

MANAUGH: So it was a great example of when someone actually has the resources to make quarantine happen, you know, and quarantine in a really rigorous, really widely and really detail-oriented way, to be implemented in this kind of place. But they do it in an interesting way. It actually recalls Michele Jacobson at the Needles border inspection station, who was saying how she tries to think like a pest. And so that means thinking about things like, you know, the treads of people’s shoes. It means thinking about containers. So when you’re bringing machinery over, it means the machinery itself. It means the computer equipment. It means, you know, the lunches of the people that might be eating, you know, and working on the island. So all of those things get thought through. You know, what would take this path and how do we prevent it from doing that?

TWILLEY: So obviously, Chevron has barrels and barrels of cash to throw at this problem, and the natural gas underneath means they can spend a fortune on quarantine and still make unbelievable profits. And what that translates to is: Chevron has completely reinvented how to do plant quarantine. This was one of the most mind-blowing things we came across in our research—an oil company developing all these incredible new tools to protect the native plants and prevent pests, diseases, and invasives from coming in.

MANAUGH: The number one thing that they realized were containers, you know, these shipping containers that go all over the world. They bring soccer balls, you know, from China to the United States and plastic goods all over Europe. And they’re constantly crisscrossing the world. But the shipping containers are built with tons of little nooks and crannies where other things can find a home. And so those little bugs, those little insects, etcetera, can kind of piggyback on the global economy and show up in places they don’t belong. And so Chevron actually redesigned the shipping container in order to get rid of some of those things. You know, they changed the wood plank floor and then made that all steel. They got rid of some of the vents that would allow things to hitchhike. And so by creating a new kind of shipping container, they dramatically right away reduced the number of invasive species that might even be at risk of getting over to Barrow Island.

GRABER: Another weirdly successful tool they developed is a video game that trains their workers to get better at thinking like a pest and then finding the pests.


MANAUGH: It’s called, of all things, it’s called Quarantine Hero.


TWILLEY: Alternate title for our book, I think.

MANAUGH: Yeah, and so Quarantine Hero, which we got to see, you know, played a brief example of, is actually just a little animated scene where you are an inspector and a series of objects is coming through and you have to spot the, you know, maybe a little seed pod that is stuck on the hem of someone’s trousers or a little bug that is, you know, attached to the back of a piece of equipment. It’s actually like competitive quarantine, which is a slightly absurd thing to imagine.


TWILLEY: Quarantine Hero has been a huge success—the Barrow Island quarantine inspectors loved it, they played it all the time, and they got better and better at catching pests in real life. It was such a hit that the Chinese government is now adapting it to train their border inspection teams.

GRABER: Of course like every inspection and quarantine facility, some things can slip through the cracks. So far it’s been pretty minor things, maybe a dandelion, some cockroaches. So Chevron has developed cool new tools to deal with those, too.

TWILLEY: And so what Chevron then invested in is these automated kind of robot things that roll around the island looking for invasive weeds, invasive species, and send back geo-referenced alerts. And then they have another whole set-up where they have 70 acoustic sensors all over the island that are listening. There’s an A.I. system listening for the specific sounds of a specific gecko that they want to keep off the island. They have track pads that can tell by the weight and the movement on the track pads, what kind of animal is it? Is it an animal that we want to keep off the island, like a rat? So they have this entire kind of, even on the island, this whole network of automated systems that are tracking to make sure anything has slipped through.

GRABER: So this sounds like it’s mostly successful and fantastically expensive and complicated for anything that is not located on an island being run by an incredibly wealthy company that wants to extract the natural resources there. Is there anything to be learned from it, though, that can help us in the rest of the world?

TWILLEY: Well, yeah. I mean, the Chinese government thinks the Quarantine Hero is going to help make their biosecurity inspection better. So we’ll see. The thing I thought that really should be introduced tomorrow are the redesigned shipping containers, because they don’t cost any more to make. They don’t weigh anymore. They’re great. They reduce the invasive species hitchhiking along almost to nothing. And I had no idea about this, but containers are just this incredible kind of weak spot in the global quarantine system. There were these researchers looking at the Port of Brisbane in Australia, and they inspected 3,000 containers. They found 1,000 live insects, and many of those were quarantinable pests. So 3,000 containers is fewer than come into Australia in a single day. So you can imagine how many live insects are coming in on containers and this redesigned shipping container… Yeah, you can’t, you know, replace every container on Earth overnight, but we should not be making the old design anymore. We should be sort of gradually subbing in the new one.

GRABER: And as for those cool-sounding robots searching for invasive weeds and animals—well, farms are getting more and more automated. The government might not be able to pay a person to plant a sentinel field to look for wheat rust, but maybe farmers can tack on a sensor that Chevron’s developed to a machine that’s already out in the field. Sounds like it could be actually kind of practical.

TWILLEY: The thing that I’m most excited about though is that Chevron has the money to do a really scientific analysis of the cost-benefit ratio of all of these different quarantine tools, so that they can discover which ones give the most bang for the buck. And they’re publishing that research so everyone can learn from it. Which is huge, because there’s never enough money to spend on quarantine and preventing plant pandemics before they happen. Unless you’re Chevron.

GRABER: So an entire book on quarantine when we’re living through a global pandemic. LAUGHS

TWILLEY: I know. It’s a cheerful topic.

GRABER: I know. A little challenging in many ways, but, so, keeping it to food, though, has thinking about food through the lens of quarantine—has it changed at all how you look at food in the supermarket? Do you look at chocolate and go, Oh, no, I’m really nervous. Do you look at a loaf of bread and go like, OK, the folks there are protecting it from rust. Like, how do you feel when you’re in the supermarket these days?

MANAUGH: Well, yeah, I mean, I definitely feel more, I guess, aware of the risks behind certain foods. I think more often, though, I find myself, you know, as a relatively recent Californian, just kind of newly appreciating California itself as a very fragile place. It’s kind of an ecological bubble. And I think that realizing the stakes—and not just the stakes economically or financially for farming and agriculture, but in terms of hunger, in terms of people being able to put food on the dinner table, all of these things seem really more tangible to me now in a way that they hadn’t been before. And to the to the extent I’d say even that, you know, I feel embarrassed, I guess in retrospect, you know, in how I sort of reacted to—you know, because when you drive into California, you go through these quarantine inspection stations, they’re not just at Needles. I even have, you know, chilling memories of, you know, lying about whether or not I had an orange in the car, that kind of thing. But so that’s one thing I took away was just the realization that I play a role in quarantine. You know, as corny as that might sound, I think that, like, it’s up to individuals to actually go along with these systems. They’re not just there to be inconvenient. They’re there to protect us, but also to protect entire ecosystems.

TWILLEY: For me, there has been a kind of growing sense of dread. I think one of the things that’s kind of interesting is that when we started reporting this book, even some medical health experts that we spoke to, you know, people at the World Health Organization and so on, they were like, Well, you know, we don’t really recommend quarantine anymore. Surely your book must be focusing on the history. Like, we don’t anticipate sort of mass lockdowns in the future. And then look where we are. And I now have a new sense of fear that the same is going to be true of the stuff we write about in the agricultural quarantine chapter. Now I’m like, well, you know, crap. All the people who are warning about, you know, we would face a pandemic. And they were even talking about novel coronaviruses. Those people were right. Maybe we should listen to the people who are warning about agricultural pests and diseases too? They might have a point also.

GRABER: I like in this place, in this situation, Geoff kind of came out as the more, Geoff, you were like the slightly more positive one. And Nicky, you were the more scared and nervous one. I feel like that’s a little role reversal there.

MANAUGH: Yeah, we’re changing each other.

TWILLEY: We’re mixing it up. We like to keep it fresh. If Geoff doesn’t inject any gloom or doom, I feel like it’s missing at this point. So I put it in.

GRABER: All you Gastropod listeners won’t know this, but in general, Nicky is the one who thinks everything’s going to work out, kind of no matter what, and Geoff is the worrier.

TWILLEY: Pretty much.

GRABER: Glad you guys are balancing each other out still. Thank you very much for your time. This has been super fascinating. LAUGHS

TWILLEY: Yeah. We really wondered about whether to do it or not.

MANAUGH: Yeah. What’s the name of this podcast again?

GRABER: So it’s called Gastropod.

MANAUGH: Ok, ok. All right.

GRABER: You can find it on any podcast app I promise.

MANAUGH: I’ll search for it on Bing.

TWILLEY: Yeah. Thank you for taking the time, Cynthia. Not that you had a choice.

GRABER: Thanks this episode to Geoff Manaugh and to Nicky, their new book is called Until Proven Safe: The History and Future of Quarantine.

TWILLEY: Just so you know it has all sorts of exciting and fascinating stories that aren’t in this episode, like when Houston was put under quarantine in case astronauts had brought back extra-terrestrial germs. Not to mention the true story of quarantine and COVID-19.

GRABER: We have a link on our website,, and we will have a link on the website where you can also get a special signed bookplate. That’s a signed sticker you can put in your book. And if this all isn’t enough, if you say at the same link that you’ve pre-ordered the book, you can be entered into a drawing for special book-themed merch! Everything is at

TWILLEY: That was… That was thorough, Cynthia. LAUGHTER. I feel like I understand what our interviewees go through now. I’m feeling a little drained.