By Becky Beyers
Consider the potato, the pomme de terre, the apple of the earth. Even though it’s one of the oldest foods known to mankind, it’s often been regarded as peasant food, the kind of thing one only consumes if there is no other alternative.
In a world where food is increasingly expensive and hard to come by, scientists and humanitarians are taking another look at the potato—the world’s number one vegetable crop and its fourth-largest food crop—and recommending it as a way to help end hunger. Citing the potato’s high protein and wealth of nutrients, the United Nations Food and Agriculture Organization has called for increased research and development. The FAO saw the need for more potatoes to help feed developing countries as so important that 2008 was designated as the “International Year of the Potato.”
At CFANS, plant breeders, biochemists, pathologists, entomologists and soil scientists are continuing a century-old tradition of working with Minnesota’s potato farmers and industry to improve the quality, yield and disease resistance of potatoes; some of that work may have implications well beyond the fields of Minnesota and North Dakota.
Potatoes were first cultivated nearly 8,000 years ago in the rugged Andes mountains of Peru; nearly 200 species have been documented, and breeders have used many of those wild species to establish modern varieties. Potatoes are grown in more than 125 countries, often in harsh climate conditions and less-than-ideal soil.
In the Upper Midwest, potatoes are grown in the rich black soil of the Red River Valley, the sandy soils of central and southern Minnesota and the peat of southern Minnesota. Growers raise round red potatoes sold to consumers for boiling and baking; russets for baking at home and for the French-fry industry; round whites for potato chips; and seed potatoes.
Christian Thill, a professor in the Department of Horticultural Science, works with potato-growing test sites in an area that ranges from western North Dakota to southeastern Minnesota. He says the industry is healthy here, usually ranking in the top five or six states in the nation. Along with the climate, growers here also face the challenge of long distances to bigger markets on the west and east coasts. A new variety of potato takes about 12 to 15 years to get from inception to market. In a given year, Thill and other potato breeders might test as many as 100,000 new combinations of varieties, weeding out the obvious duds in the first year and narrowing the numbers down to about 15 varieties in their eighth year of testing. Evaluating each variety’s resistance to disease, yield and other characteristics takes time and experience, Thill says. “It’s a science and it’s an art—you have to develop a breeder’s eye for the traits that the industry is looking for.”
Those traits vary depending on the potato’s intended use. For example, a Russet likely will be used to make French fries, so the industry wants a long, oblong-shaped potato that can be cut into strips with little waste, but it also must have the right kind of French fry color and snap and it must not bruise easily. Round whites have to slice evenly into thin, round discs and have skin that peels right off for making potato chips.
“It’s all industry-driven and consumer-driven,” Thill says. “If a potato variety has strong disease resistance but not the right fry color, it’s no good. When you go to the store to buy potatoes for boiling or mashing, you want a nice red skin that stays on until you peel it.”
Those kinds of characteristics might someday lead to development of a potato with high name recognition and the ability to command premium prices, sort of the ‘Honeycrisp’ apple of potatoes.
“We’re not there yet, but it could happen,” Thill says. “We haven’t specifically bred for taste and texture—people like to bite into the ‘Honeycrisp’ because of how it tastes and the crispness, but we don’t have a potato yet like that. Up until now, we’ve concentrated on breeding potatoes for a specific use. But there’s a way to get there eventually.”
Late blight, the disease responsible for the Irish potato famine of the 1840s, still poses the biggest threat to non-seed potato growers, says Jim Bradeen, a professor in the Department of Plant Pathology who specializes in potato disease. Part of late blight’s potency comes from how quickly it can kill a crop; within a week to 10 days, an entire field can be wiped out, he says. Most U.S.-grown varieties are susceptible, particularly in years with cool, wet conditions. Fungicides work on some pathogen strains, but because the disease is so fast-acting, farmers have to spray the fungicides before the disease strikes—an expensive and less-than-environmentally friendly solution.
Bradeen’s lab concentrates on using the disease resistance genes found in wild species of potato to breed new varieties with other desirable traits. Because molecular tools and technology are advancing so quickly, scientists are close to having a pyramid of disease-resistant genes that can work together against ever-changing diseases. “Historically, we thought of improving the plant as the primary defense against disease,” he says. “But the pathogens also are changing. We have to find not just what works now, but what will work in the future.”
Seed-potato growers in Minnesota and North Dakota benefit from nearly ideal conditions for growing seed potatoes—long, cold winters that kill off most diseases and pests followed by hot summer days with cool nights. Still, they face threats, both environmental and financial.
Viral diseases pose the greatest dangers to seed-potato production. A serious outbreak of PVY—Potato Virus Y—in the early 1990s led to major losses in Minnesota. The disease, which is transmitted by aphids, stunts growth, reduces yield and kills the potato plants. Scientists in CFANS have experimented with integrated pest management solutions to the problem, but it hasn’t yet been resolved.
Because seed potatoes must be certified and inspected before they can be sold, PVY creates an economic problem as well, Thill says. Establishing a seed-potato operation takes about five years. A beginning grower often can pay about $30 per pound for the mini-tubers needed to get started, and most assume they’ll pay that off in about three years. But if PVY invades and prevents certification after two years, the new farmers can’t afford to stay in business.
Still, the outlook for potatoes remains strong both in Minnesota and worldwide. Production more than doubled in developing countries around the world between 1991 and 2007; China and India are now the top and second-place producers of potatoes. Because the population of those countries is expanding so rapidly and so much food is needed, potatoes likely will become a staple food in parts of the world where it hadn’t been seen much until recently.
Thill also sees the potential for new niche markets in Minnesota, whether it’s in novelty potatoes—he has a ‘Golden Gopher’ variety with maroon skin and gold insides, for example—or in emphasizing that potatoes can be locally grown. “We’re innovators,” he says. “We can always make it even better.”