Potatoes

The potato is the largest non-cereal food crop on earth and the fourth most important food staple after maize, wheat, and rice, with world production around 383 million tonnes a year. It is a New World crop, domesticated in the Andes of Peru and Bolivia roughly 8,000 to 10,000 years ago and carried to Europe by the Spanish in the sixteenth century, where its calories per acre helped drive population growth and, when the late-blight fungus arrived, the Irish Famine of 1845 to 1852 that killed roughly a million people and pushed one to two million more to emigrate. Production has shifted decisively to Asia: China is now the largest grower at roughly 24 percent of world output and India is second, the two together close to 40 percent, while Europe and North America have moved from fresh table potatoes toward processed products. Less than half of all potatoes grown are now eaten fresh; the rest are turned into frozen french fries, crisps, dehydrated flakes, and starch, fed to livestock, or held back as seed tubers.

For all that scale, the potato has almost no futures market, and the reasons are a checklist of what makes a commodity hard to trade on an exchange. Potatoes are bulky and low in value per tonne, so freight dominates and markets stay regional. They are highly perishable, which makes a standardized storable deliverable grade hard to define. They come in many varieties and quality grades. And most of the crop never touches an open market at all: it is grown under contract directly between farmers and a handful of processors, who set the price. The one serious listed contract today, the EEX European Processing Potato future, a 25-tonne cash-settled contract priced off a northwest European index, is itself thin and is being delisted in June 2026, which will leave no liquid exchange-traded potato market anywhere.

The cautionary tale sits in the history. The New York Mercantile Exchange once listed a Maine potato future, and in May 1976 it produced the largest delivery default in the history of US futures: sellers of almost a thousand contracts, roughly 50 million pounds of potatoes, simply failed to deliver. The Idaho potato magnate J. R. Simplot and the Washington grower Peter Taggares were the principal shorts, betting the contract was overpriced and refusing to make good. The CFTC fined them, litigation dragged on for years, and the contract never recovered; it was delisted in the mid-1980s and is still cited as the reason the United States, despite being a major grower, has no potato futures. Price-setting instead runs through the four processors that dominate the frozen-fry business, McCain Foods, Lamb Weston, J. R. Simplot, and Aviko, whose multi-year grower contracts cushion most farmers while leaving the small free-buy spot market violently volatile. That split was on display in 2024, when poor harvests across the wet northwest European processing belt drove spot processing potatoes to record highs, and again in 2025, when a record harvest produced a glut that collapsed free-buy prices even as contracted growers were largely insulated.

New potatoes and old potatoes are not different varieties but the same crop caught at different stages. A new potato is harvested young, before its skin has set, so the skin is thin and rubs off, the flesh is waxy and high in moisture, the starch is low, and it does not keep; it is a fresh early-summer treat, the Jersey Royal and Charlotte the classic examples. A maincrop, or "old," potato is left in the ground to mature until the skin sets, then cured for a week or two in warm humid air to toughen that skin for storage. Cured maincrop potatoes keep for six to ten months in a cool, dark, humid, ventilated store. Temperature is a balancing act: cold storage triggers cold-induced sweetening, where starch turns to sugar, which is harmless for boiling but ruins frying potatoes because the sugar browns, turns bitter, and raises acrylamide, so processing potatoes are stored warmer, around seven to ten degrees Celsius, than colder-kept seed potatoes. Light is the other enemy, greening the tuber and raising toxic solanine, which is why potatoes are kept and sold in the dark. The sprout suppressant CIPC (chlorpropham) that the industry leaned on for decades was banned in the EU and UK around 2020, and growers switched to mint and clove oils, ethylene, and other gentler treatments.

There is an astonishing number of potato varieties, roughly 4,000 native kinds in the Andes alone and more than 5,000 worldwide, and they were not always there; they accumulate because of how the plant reproduces. A potato is grown clonally from a seed tuber, a piece of the parent, so every plant is a genetic copy, but the potato is also a highly heterozygous tetraploid, so on the rare occasions it sets true seed the offspring are wildly variable, and any promising new seedling can be fixed instantly as a permanent variety just by replanting its tubers. Andean farmers exploited this for millennia, selecting distinct potatoes for every altitude, soil, frost level, pest, and cooking use, which is why a single Peruvian highland market can hold dozens of shapes and colors. Modern breeding then piled on thousands more selected for yield, disease resistance, storage, and processing, so the count keeps climbing rather than being an ancient fixed set.

There is very much a french-fry potato, and it is the Russet Burbank, descended from work by the breeder Luther Burbank in the 1870s. It dominates fry production, around seventy percent of US processing acreage, and is McDonald's mainstay alongside the Ranger Russet, Umatilla Russet, and Shepody. Three traits make it ideal: a high dry-matter (starch) content, so the fry cooks crisp and soaks up less oil; a long, uniform shape that yields long even fries; and low reducing sugars, so the fry does not brown or turn bitter in the oil. Those same low sugars are why storage temperature matters so much for processing potatoes.

If the potato yields more calories per acre than wheat or rice, and it does, the obvious question is why it never replaced them. The answer is storage and trade. A grain is dry, durable, and fungible: wheat or rice can be stored for years, shipped across oceans, taxed, lent, and traded as a uniform commodity. A potato is about eighty percent water, bulky and perishable, rots in months rather than years, cannot be milled into a storable flour, and has to be regrown from bulky seed tubers rather than a handful of light grain. So the potato became a magnificent local subsistence crop, credited by the economists Nunn and Qian with as much as a quarter of Old World population and urban growth between 1700 and 1900, yet it could never become the storable, tradeable backbone of grain markets and empires the way the cereals were. It complemented grain rather than replacing it.

Late blight, the Phytophthora infestans behind the famines, has never had an outright cure; it is only ever managed. The first real control was Bordeaux mixture, a blue slurry of copper sulfate and lime that the Frenchman Pierre-Marie-Alexis Millardet noticed in 1882 was keeping sprayed grapevines free of mildew and published as a fungicide in 1885, the world's first. Blight is still fought on the same principle, fungicides plus resistant varieties, the newest of which are GM and cisgenic potatoes carrying resistance genes borrowed from wild Andean relatives. And Ireland was not the only potato famine: the same blight pandemic caused the European Potato Failure of 1845 to 1847, which killed tens of thousands across Belgium, the Netherlands, and Prussia and fed the unrest behind the 1848 revolutions, and the Scottish Highland famine of 1846 to 1856, which killed far fewer but emptied the Highlands through mass emigration. The 1840s blight was a continent-wide disaster of which Ireland was simply the worst-hit corner.