I’ve never liked mushrooms. Some of them are poisonous, and despite several years as a Boy Scout, I still don’t know which ones, so why take chances? Nor am I fond of mold in bathrooms or on leftovers, or even in those annoying online ads featuring unsightly toenail maladies.

Yet some forms of fungus are undeniably good. Penicillin fights bacterial infections. Without yeasts, we’d have no fermented beverages such as beer and wine or some of the foods we enjoy when imbibing (think pizza crust). Mold is also crucial in some cheeses.

But Emily Monosson’s Blight: Fungi and the Coming Pandemic focuses on the negatives: how fungi can wipe out flora and fauna and how the world may change dramatically as a result. Among other things, the novelty song “Yes! We Have No Bananas” may make sense again — just as it did a century ago.

A few of the book’s early pages are perhaps a bit too technical, including what is easily the most boring sex scene ever published — a detailed account of how certain fungi reproduce. That, however, leads into a fascinating explanation of how fungi once quickly infected and killed almost every American chestnut tree. (Genetic engineering offers hope that the once-ubiquitous species can be returned to its former glory. It could take centuries before there’s a mature chestnut forest in the eastern United States again, but you know what they say about the best time to plant a tree.)

Humans, not surprisingly, often unwittingly aid and abet destructive fungi. We help them hitch rides around the world aboard plants, animals, and ourselves, introducing them to new hosts with little or no resistance. Sometimes we become those hosts, and recent outbreaks of fungal infections affecting humans are baffling and frightening. While external infections such as athlete’s foot are obvious and easily treated, internal infections can be insidious and deadly. As Monosson observes:

“We haven’t simply opened Pandora’s box; we have swung it around and shaken out the contents.”

It’s a problem with a spellbinding history. In 1898, the first head of the U.S. Department of Agriculture’s Office of Seed and Plant Introduction enthusiastically traveled the world collecting specimens from plants seen as possible crops (pistachios, nectarines, lemons, etc.) for American farmers to grow. A USDA colleague and lifelong friend (who quickly became a former friend) fretted that importing carelessly might spread disease and pushed for legislation prohibiting the importation of exotic plants. Hard pushback by nurseries and horticulture societies defeated the effort, although in 1912, a shipment of fungal-infected cherry trees from Japan led Congress to pass the Plant Quarantine Act, establishing some controls.

The rules, unfortunately, have proved to be porous and difficult to enforce given the huge amount of plant products imported into the U.S. Alarmingly, fewer rules apply to the vast majority of the more than 200 million animals brought into the country each year.

To an extent, it’s an honor system. Those questions you’re asked at the airport when returning to the U.S. about whether you’ve got any fruits or vegetables? Take them seriously. Last year, I absentmindedly carried a single banana across the Atlantic from London and was busted by a well-trained sniffer dog. I spent the next half-hour in a holding area before the Customs and Border Protection agricultural rep was convinced I appreciated the gravity of my innocent mistake — one potentially subject to a $1,000 fine.

Of course, lots of bananas travel (and only a small percentage are sampled for pathogens). They’re the world’s fourth-most-important crop — after maize, wheat, and rice, all of which are vulnerable to fungal infections. Americans were introduced to the tropical fruit in the late 19th century; we each now eat an average of 27 pounds of bananas a year.

But today’s cereal topper is a different banana than it used to be: The once-standard Gros Michel variety was almost entirely wiped out by a fungal blight early in the 20th century, and the industry quickly turned to the Cavendish variety for export to the Western world. It seemed to resist infections — for a while. But banana growers repeated earlier errors by focusing on just one variety and planting densely, and the breakfast staple is again threatened.

“Monoculture” effectively puts all the eggs in one basket, greatly increasing the cost of an accident. Growers want (and consumers demand) the prettiest, tastiest, and most productive crops, so they sacrifice the disease resistance that nature can provide. The likely outcome? We might be eating a different type of banana in a few years, perhaps one that’s a different size and a different color, with a different taste. Or genetic engineering, increasingly considered to be more acceptable and even necessary, might save the Cavendish.

Blight also considers in detail the devastating effects that fungi have had on pine trees, bats, frogs, and salamanders, among other species. And there’s a captivating look at how some scientists feared space exploration would lead to us inadvertently sending deadly fungi into space and hurting life elsewhere in the universe, as well as at what those scientists have done to prevent intergalactic samples from contaminating Earth.

Monosson is quick to provide her perspective on those efforts:

“When compared with our lackadaisical approach to preventing the next earthly plague that is surely waiting in the wings of a bird, on the back of a frog, at the edge of the forest, and in the field, it is astonishing. That an alien plague could be brought to Earth in a sample can or by returning spacecraft is an extremely small probability event; that we will provide an opportunity for the next earthly viral, bacterial or fungal plague to take hold is a near certainty.”

What might hasten that “coming pandemic” mentioned in the book’s title? Ironically, one answer is modern medicine: the ever-growing number of people who are vulnerable due to compromised immunity from organ transplants or HIV or cancer treatments. Fungal infections in humans can be time-consuming to diagnose and much harder to treat than viral or bacterial infections. Meanwhile, climate change provides fungi with new opportunities to adapt to the high body temperatures that have historically protected us.

How might we prevent or at least delay these looming disasters? The author suggests that we should decide:

“...to take responsibility for how we operate in this world and beyond...end the trade in wild animals...agree to testing protocols...be more thoughtful about where we’ve been and where we are going and if the mud on our shoes or the plant we’ve stuffed in our backpack might set off the next pandemic.”

In other words, that banana in your carry-on? Ditch it before you board.

Randy Cepuch, a longtime book selector and reviewer for the Independent, will never, ever, ever try to bring a banana into the U.S. again.

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