In the Garden:
New England
December, 2011
Regional Report

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As potatoes made their way from their Andean home across the globe, they changed the course of world history.

Potatoes and the Columbian Exchange

The potato is often regarded as the Rodney Dangerfield of the vegetable world -- it just can't get no respect. Demonized as a contributor to the obesity epidemic or seen as simply an economical source of calories, this humble looking tuber is actually surprisingly nutritious. And in terms of plants that changed the course of world history -- socially, politically, economically, and ecologically -- there are few other crops that can compete with its influence.

The Columbian Exchange
Potatoes were unknown to the world outside the high elevations of the Andes before that truly world-changing event, the arrival of Columbus to the New World. The influx of Europeans and Africans to the Americas that followed set in motion a chain of events that changed the face of the entire world. And many of these changes related to plants -- potatoes, maize, sweet potatoes†, tobacco, and rubber trees, crops previously unknown to the rest of the world.

The story of how the world changed when the Americas were linked first with the Europe and then with China and other parts of Asia is the subject of a fascinating book aptly titled 1493: Uncovering the New World Columbus Created (Alfred Knopf, 2011). Author Charles Mann details the wide-ranging changes that happened all over the globe as a result of the Columbian Exchange, geographer and historian Alfred Crosby's term for the ecological and economic exchange of plants, people, minerals, insects, and diseases that underlay major global changes such as the development of the African slave trade, the rise of European power, and the demise of imperial China, and whose influence continues to this day. According to Mann, "To ecologists, the Columbian Exchange is arguably the most important event since the death of the dinosaurs."

Potatoes and the Rise of the West
So how does the lowly potato fit into all of this? When Spanish explorers arrived in the Andes, they found the people there cultivating a wide range of potato varieties adapted to specific conditions of elevation and soil. Unlike grains, potatoes are much more productive on a given amount of ground, and also unlike grains, potatoes contain sufficient nutrients to serve by themselves as the basis of a reasonably healthful diet. Although the acceptance of potatoes in Europe was slow initially (it was the first food they grew from tubers, rather than seeds, and was regarded with suspicion, even denounced as "an incarnation of evil" since it was not mentioned in the Bible), once it became accepted, it played a huge role in ending the hunger and famines that had previously been routine in Europe. Says Mann, "Hunger's end helped create the political stability that allowed European nations to take advantage of American silver. The potato fueled the rise of the West."

The Great Hunger
But of course, potatoes went on to help create the Great Hunger, the famine that ensued in the wake of the devastating arrival of potato blight in the mid- 19th century, another import from the New World. This fungus-like organism is thought to have reached Europe in a load of guano, bird excrement that is mined for use as fertilizer. Found on Pacific Islands off the coast of South America, guano had been used by Andean peoples to fertilize their potato fields. Europeans imported this cultivation technique as well, the beginning of the use of high-intensity fertilizers to improve crop yields that helped to make the potato such a staple and support Europe's rise in population.

Unlike in the Andes, the potatoes grown in Europe had little genetic diversity -- half of the Irish potato crop consisted of one especially productive variety. Add to this changes in agricultural techniques that allowed the disease to spread easily and the stage was set for an epidemic of disastrous proportion. The suffering that ensued was horrific, especially in Ireland, which endured one of the deadliest famines in history in terms of the percentage of the population that died. The hundreds of thousands who fled from Ireland to escape the famine changed the course of history in this country and my own personal history as well. My paternal great-grandparents came from Ireland to escape the famine, as did my husband's maternal great-grandparents.

Battling Beetles with Paris Green
Beginning in this country in the 1860s, another scourge descended upon potatoes. A beetle, yellow-orange with black stripes, attacked a potato patch in Kansas. This native insect, which had previously fed exclusively on buffalo bur, a weedy potato relative, had adapted its preferences and was soon dining on potatoes with a vengeance. Thus began the battle with what came to be known as the Colorado potato beetle, which rapidly expanded its range and is now found across the country.

In a continuation of the Columbian Exchange, the beetle made its way to Europe, despite the world's first agricultural quarantine, where it decimated potato fields there as it did in the U.S., eventually spreading across much of Asia as well. Efforts to control the beetle were the beginning of the use of toxic chemicals to kill insect pests. Supposedly by chance, it was discovered that Paris Green, an arsenic and copper laced paint, would kill the beetles when mixed with flour or water and dusted or sprayed on potato plants. This led in turn to the discovery that copper sulfate controlled potato blight. Some people worried about the toxicity and the cost of these chemical controls, but many embraced them as the wave of the future.

It didn't take long -- as early as 1912 -- for another of the downsides of chemical controls to become apparent. Potato beetles began to develop resistance to Paris Green and copper sulfate, beginning what has been called the "toxic treadmill." Newer and often more toxic compounds are introduced, and the beetles respond by developing resistance, adapting more quickly each time. The beetle is reputed to have developed resistance to 52 compounds belonging to all major insecticide classes in the space of about 50 years. Today, potatoes, the fifth most important crop worldwide, are also one of the most heavily doused with chemicals in an ever escalating battle against insects and disease. One of the foundations of the modern agro-industrial complex based on improved crops, artificial fertilizers, and chemical pesticides, conventional potato culture demonstrates the weakness and inherent unsustainability of this way of farming.

Give 'Em Some Respect
All this fascinating history points to why potatoes are a great crop to grow in the home garden. When they are not fried in buckets of oil or mashed with gobs of butter and cream, potatoes are actually quite healthful veggies. Their protein content is similar to that of cereals. Rich in vitamin C and moderately high in iron and other vitamins and minerals, they are also a rich source of cancer-fighting antioxidants, especially red and purple-fleshed varieties. And these healthful compounds are highest in potatoes that haven't been stored for long periods of time, as many commercially produced spuds are.

In the fight to keep pests and disease at bay, conventionally grown potatoes are today routinely treated with a mind-boggling array of insecticides, fungicides, herbicides, and fumigants. They have made the Environmental Working Group's Dirty Dozen list of crops most likely to contain pesticide residues.

But when grown on a small scale in the home garden, your potatoes can be fresh, loaded with nutrients, free from toxic residues and, best of all, delicious! Imagine freshly harvested new potatoes, tossed with olive oil and a little salt and pepper, then roasted to perfection with crisp exteriors surrounding tender flesh. Now that deserves some respect!

† While sweet potatoes are thought to have originated in parts of what is now Central and South America, they also found their way -- no one is sure how -- to the islands of Polynesia prior to the age of Western exploration. The Columbian Exchange took them via Spanish settlements in the Philippines to China, where they played as significant a social, political, economic, and ecological role as the potato did in Europe.

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