By: Mary Ellen Ellis
Wild potato information may not seem like something theaverage home gardener needs, but it’s more important than you realize. A wildpotato, native to South America, has natural pest resistance. Now, crossed withdomestic potatoes,you can order a new cultivar from suppliers that will allow you to grow tastypotatoes without using pesticides.
A potato with hairs is actually a potato plant with hairyleaves, not hairy tubers. The original hairy potato, Solanum berthaultii,is a wild species native to Bolivia, and probably the ancestor of thedomesticated South American potato plant.
The hairy potato grows three feet (1 m.) and taller. Itproduces purple, blue, or white flowers and green, speckled berries. The tubersare too small to be valuable for eating and the plant naturally grows in dryregions of Bolivia at high elevation.
The most important of all hairy potato traits though is, infact, the hairs. Known scientifically as trichomes, these sticky hairs coverthe leaves and protect them from pests. When a small pest, such as a fleabeetle, for example, lands on the leaves, it gets trapped in the stickyhairs. It cannot feed or escape.
Larger pests may not get stuck but still seem to be deterredby the stickiness. Researchers have also found that a potato with hairs hassome resistance to other diseases, including mildew. Why the hairy leaves wouldprovide this resistance is still unknown.
You can now get hairy potato pest resistance, at least inthe U.S., by growing hybrid crosses of domesticated and wild potatoes. Just acouple of hybrids have been created, but they combine the tasty, large tubersof the domesticated potato with the natural pest resistance of the wildspecies.
For home gardeners, this means you can grow potatoes withlittle or no pesticides, completely organically. Two varieties that are availableinclude ‘Prince Hairy’ and ‘King Harry.’ The latter is the preferred cultivarbecause it has a shorter time to maturity. ‘Prince Hairy’ can take up to 140days to mature whereas ‘King Harry’ needs just 70 to 90 days.
Check with online seed suppliers to find ‘King Harry.’ It isnot yet available widely but there are distributors in the U.S. offering thispotato. Organic suppliers in particular are likely to have it for sale.
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The potato is a great food producer and easy to grow. Unlike some other vegetable plants, however, the only edible part a potato produces is the tuber. Potato leaves can be toxic and even some other parts of the plant can cause problems given the right conditions. That's because potatoes protect themselves with solanine.
Potatoes belong to a group of plants called nightshades. Other members of the nightshade family include tomatoes, peppers and eggplants. Closely related to tobacco, which produces the poison we call nicotine, nightshade plants produce solanine. The alkaloid is part of a potato’s chemical defense system, protecting the plants from insects, diseases and other predators.
Solanine is produced in potato plants when they are exposed to the sun. That’s one reason why potatoes are hilled – covered several times with soil as they grow. If the tubers are exposed to light, their solanine content can be high. Even when properly hilled, potatoes may still contain solanine. The solanine is also present in sprouting stems, fruits and leaves, in varying concentrations.
The symptoms of solanine poisoning vary according to the amount consumed and an individual’s sensitivity to the alkaloid. Potato leaves are likely to be quite high in solanine. Symptoms include:
While the whole potato plant, including the leaves, contains solanine, potatoes that are not green are still safe to eat. Research has shown that when the tubers are boiled or fried, the solanine leaches into the water or oil. You should still trim obvious green spots from the potatoes, as they are an indication of sun exposure, which increases solanine. In any case, don’t eat the leaves, raw or cooked.
It’s possible that any confusion about whether you can eat potato leaves comes from the name potato being used for two very different plants. The sweet potato is not a nightshade – it belongs to the morning glory family. The shoots, stems and leaves of the sweet potato are not only edible, they are an important food source in many tropical areas. They are usually steamed or stir-fried.
Although potato leaves are not edible, they have some other interesting qualities. Leaves are where the first signs of an insect infestation will occur. The Colorado potato beetle and its larvae can decimate a potato field in a couple of weeks, leaving only skeletons. Some potatoes have hairy leaves that can help repel this pest. Leaves can also indicate nutrient problems and too much or too little water.
AS the impacts of climate change intensify — from water scarcity to raging fires and disease outbreaks — the ability to keep pace with demand for food will increasingly rely on crops adapted to new conditions. To achieve this, crop breeders will need the full range of tools at their disposal, a report by Oscar Ortiz, Deputy Director General for research and development for the International Potato Center, reveals.
So while conserving flora and fauna in their natural habitat remains an immediate priority, global food security in the long term must be futureproofed through continued investment in the preservation of plant genetic material.
Tomatoes affected by late blight in a garden near Hilo, Hawaii. Photo: Scott Nelson/Flickr (public domain)
A model for this futureproofing exists at my organization, the International Potato Center (Centro Internacional de la Papa, or CIP) in Lima, Peru. Here we host the world’s most extensive collection of potato and sweetpotato material, which conserves more than 15,000 samples of root and tuber crops. This genetic material can be drawn upon to minimize disruption to food supplies if one variety is lost to natural causes like disease or human-caused processes like climate change.
The threat is far from theoretical. Already more than a dozen varieties of native and wild potatoes are in danger of disappearing due to temperature changes or loss of habitat, while diseases are emerging in new places to endanger other popular crops, including varieties of wheat and bananas, and their wild relatives. In total two-fifths of the world’s plants are at risk of extinction, according to new research.
Wild potatoes and sweet potatoes are the cousins of the third- and sixth-most important food crops on the globe. These wild species, although inedible themselves, are rich with hardy genetic traits that can be used to breed more nutritious, disease-resistant varieties of crops that underpin diets and incomes around the world.
For example, researchers have found that wild species of potatoes contain genes that provide resistance to late blight, the most destructive potato disease, which causes an estimated $6.7 billion in yield losses worldwide every year. The loss of just one wild potato species could both set back progress toward reducing losses to late blight and hinder recovery from large-scale outbreaks in the future.
Varieties at the CIP genebank. Photo: Sara A. Fajardo/CIP (provided)
To provide defenses against such a future food apocalypse, collections of genetic material — not just of potatoes, but all crop species and their wild relatives — must be continually conserved, tested and renovated, requiring ongoing funding, research and innovation. With plant genetic material being a common good shared by and essential to all, it is in the interests of governments, development organizations and the private sector to make crop conservation a funding and policy priority.
Just as digital backups moved the world from storing information on floppy disks to the cloud, recent advances in genetic conservation techniques, such as DNA sequencing for digital catalogs and cryopreservation, offer new opportunities to preserve these staple crops for future generations facing new scenarios.
The CIP genebank — one of 11 CGIAR genebanks protecting the planet’s crop diversity — began to cryopreserve crops in 1996 and now has the most advanced cryopreservation practices for potatoes.
Cryopreservation allows for the long-term storage of plant material in liquid nitrogen at temperatures of -320F (-196C). Among the advantages, for crop material, of cryopreservation over in vitro conservation are the time and resources saved — both in day-to-day maintenance of storage facilities and in the need to regenerate in vitro accessions, or plant material, every 1 to 2 years.
José Cardenas, right, works in the cryopreservation section at the International Potato Center’s genebank. Photo: Sara A. Fajardo/CIP (provided)
Scientists are currently in the process of cryopreserving all potato genetic material while developing ways to cryopreserve the more delicate sweet potato to help secure the availability of safe, nutritious crops into the future.
Maintaining diverse reserves of the widest possible variety of genetic material offers the greatest chance of protecting the public from potential food shortages. Indeed, breeders must screen thousands of potatoes over many years to identify only one or two that address the needs of farmers in terms of productivity and climate resilience.
Without a reserve of potential material to screen, important advances in new crop varieties would be stymied.
Meanwhile the cost-effectiveness of cryopreservation means more funds have been invested in other areas of research. In vitro conservation is incredibly labor intensive, requiring ongoing maintenance by specialized staff. But cryopreserved samples can remain in deep freeze for decades with little oversight necessary, freeing up more resources to dedicate to the conservation of greater crop biodiversity in natural habitats, the development of a generation of virus-free germplasm, and the repatriation and rediscovery of native varieties.
Now Is the Time
Despite their values, digital catalogs and the cryopreservation of crops and wild food plants remain under-appreciated, underfunded and underutilized by governments and international governing bodies.
Food security is national security, meaning genebanks could hold the vaccines needed for humanity’s survival of a food disaster. Put simply, bioversity loss weakens our defenses.
Source: https://cipotato.org/ Photo: International Potato Centre
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A hand-painted wooden sign marks the entrance to Steven Cannon's community garden, tucked between a sidewalk and some train tracks in Ames, Iowa. It depicts the iconic image of a seedling poking from a mound of dirt. At the far end of the garden, Cannon, a tall and reedy geneticist for the US Department of Agriculture, digs into the soil with a shovel and then his bare hands, pulling up fistfuls of lumpy roots. Strip the scene to its essence—ignore the cars driving past and the power lines strung overhead—and you could be watching a Neolithic farmer. They collected seeds from wild plants, buried them near their homes, and harvested the crop, hoping it would be bigger and better than the last one. That simple act—agriculture—came to define us as a species.
Cannon isn't trying to re-create the past, though. He's inventing the future. On this fall afternoon, his team is harvesting tubers that resemble dark-skinned fingerling potatoes. They're called Apios americana, the potato bean—a legume endemic to North America. Native Americans gathered them and may even have served them at the first Thanksgiving. European settlers found them thriving in their cranberry bogs—places with low light, few nutrients, and bad soil. But they didn't bother domesticating them into an agricultural staple.
After a couple hours of labor, Cannon's harvest is complete. A dozen rubber bowls overflow with dirt-crusted tubers. Still, he is disappointed. “We were hoping for a little better yield,” he says. “This is about average.” Average is fine if you're just messing around in a kitchen garden. But Cannon is up to something far more essential. The potato bean is part of his plan for remaking our food supply from the ground up. He doesn't want to just grow Apios. He wants to turn it into a new crop that could help feed the world.
8 TBS unsalted butter (Potato beans, which have three times the protein of their namesake starches, might be a little dry, so this recipe compensates with extra fat.)
¼ TSP freshly ground black pepper
¼ TSP freshly ground nutmeg
Peel tubers, then boil until soft, about 10 to 15 minutes. Drain and mash. Add half-and-half or milk. Mix in butter and then pepper, nutmeg, and salt. Serve topped with goat cheese.
We need new crops. Thousands of years of breeding and decades of genetic modification have made the crops we sow predictable, easy to harvest, and capable of feeding more than 9 billion people. But they are also vulnerable to disease, pests, and the whims of weather. That's troubling, because global warming is bringing more disease, more pests, and more whimsical weather. On current trend lines, global wheat and soybean harvest yields could fall by nearly 30 percent by midcentury. Corn yields could drop by 7.5 percent. In the baking-hot European summer of 2003, plant growth fell by 30 percent. By 2050, that kind of summer will be the new normal. “Suppose the US breadbasket ends up with a climate like Texas,” Cannon said at a genetics meeting last year. “We need to look to species already adapted to extremes.”
The potato bean is one of those species. Versatile like a potato, protein-rich like a bean, with a flavor vaguely like a starchy peanut, Apios does well in both dry and soggy soils. And there are plenty of others like it. Roughly 18,000 species of legumes grow around the world. They're packed with protein and help fertilize the soil. Yet people have domesticated fewer than 50, and commonly eat only half that many. Cannon has assembled a short list of additional candidates: marama beans, yehub nuts, lupine, and a bunch of other so-called orphan crops, wild edible plants that could change the face of agriculture if someone could just turn them into reliable crops.
Gentl & Hyers
Domestication made humans the first species on earth to have a secure, reliable food supply, enabling the development of culture and technology and medicine. Every facet of modern society is built on its back. Yet somewhere along the way, we stopped innovating. Cannon is one of a small but committed band of researchers who are quietly trying to create new crops. They're messing with new versions of wild sunflowers that have bigger, oilier seeds and don't need as much water. They're working on a genetic rewrite of the chickpea, selecting traits that will help it thrive in a warming world.
Climate change is making the mission imperative the genetic revolution is making it feasible. That harvest from Cannon's neighborhood garden might have been disappointing, but it was also the first shot in the next green revolution.
Domestication is evolution—with human beings at the controls. When nature is in charge, evolution selects living things based on traits that favor their survival we humans select instead for traits that promote yield, flavor, predictable growth, and resistance to attack. We started doing it mainly because we could. In the Paleolithic era, fluctuations in climate made it hard for groups of humans to rely too heavily on particular plants. But when the climate stabilized after the last ice age, around 12,000 years ago, we could pick and choose. Around the world, farming impulses stirred in different societies. People from divergent cultures began actively managing many of the same wild plants during the same period. From the several thousand plant species that prehistoric people regularly relied on for food (out of roughly 50,000 species that are edible), our ancestors chose just a handful, all grasses, to form the bedrock of their diets.
Those domesticated organisms often bear little resemblance to their wild ancestors. Ten thousand years ago in what's now Mexico, for instance, farmers took a weed called teosinte and created corn. Teosinte's tiny ears contain only about a dozen kernels an ear of modern-day maize has about 800. Selective breeding turned a scruffy grass into a starch-packed staple of the global meal.
It sounds simple, but humans haven't domesticated a new staple crop for thousands of years.
What domesticated food crops do look like, however, is each other. Many of the traits we humans selected are the same regardless of the species. We want plants that hold on to their seeds rather than drop them to the ground, which plant scientists call “shattering.” We want those seeds to be large and to sprout when sown, and we want all the seeds to mature at roughly the same time. Together, these features make up what scientists call “domestication syndrome,” the combined qualities that distinguish, say, corn from teosinte.
Much of what we eat today was domesticated when people were just learning to weave clothing and still thousands of years from developing an alphabet. Today we tinker—but only at the margins. Maybe we get higher yield here or resistance to corporate herbicide over there. As far as transforming plants from the wild into new well-bred row crops, though, progress pretty well stopped a millennium before Jesus ate a matzo. Macadamia nuts, kiwifruit, vanilla bean: All arose in the Common Era. But as far as major crops go? Zilch.
The English word potato comes from Spanish patata (the name used in Spain). The Royal Spanish Academy says the Spanish word is a hybrid of the Taíno batata ('sweet potato') and the Quechua papa ('potato').   The name originally referred to the sweet potato although the two plants are not closely related. The 16th-century English herbalist John Gerard referred to sweet potatoes as common potatoes, and used the terms bastard potatoes and Virginia potatoes for the species we now call potato.  In many of the chronicles detailing agriculture and plants, no distinction is made between the two.  Potatoes are occasionally referred to as Irish potatoes or white potatoes in the United States, to distinguish them from sweet potatoes. 
The name spud for a potato comes from the digging of soil (or a hole) prior to the planting of potatoes. The word has an unknown origin and was originally (c. 1440 ) used as a term for a short knife or dagger, probably related to the Latin spad- a word root meaning "sword" compare Spanish espada, English "spade", and spadroon. It subsequently transferred over to a variety of digging tools. Around 1845, the name transferred to the tuber itself, the first record of this usage being in New Zealand English.  The origin of the word spud has erroneously been attributed to an 18th-century activist group dedicated to keeping the potato out of Britain, calling itself The Society for the Prevention of Unwholesome Diet (S.P.U.D.). It was Mario Pei's 1949 The Story of Language that can be blamed for the word's false origin. Pei writes, "the potato, for its part, was in disrepute some centuries ago. Some Englishmen who did not fancy potatoes formed a Society for the Prevention of Unwholesome Diet. The initials of the main words in this title gave rise to spud." Like most other pre-20th century acronymic origins, this is false, and there is no evidence that a Society for the Prevention of Unwholesome Diet ever existed.  
Potato plants are herbaceous perennials that grow about 60 cm (24 in) high, depending on variety, with the leaves dying back after flowering, fruiting and tuber formation. They bear white, pink, red, blue, or purple flowers with yellow stamens. In general, the tubers of varieties with white flowers have white skins, while those of varieties with colored flowers tend to have pinkish skins.  Potatoes are mostly cross-pollinated by insects such as bumblebees, which carry pollen from other potato plants, though a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties. 
After flowering, potato plants produce small green fruits that resemble green cherry tomatoes, each containing about 300 seeds. Like all parts of the plant except the tubers, the fruit contain the toxic alkaloid solanine and are therefore unsuitable for consumption. All new potato varieties are grown from seeds, also called "true potato seed", "TPS" or "botanical seed" to distinguish it from seed tubers. New varieties grown from seed can be propagated vegetatively by planting tubers, pieces of tubers cut to include at least one or two eyes, or cuttings, a practice used in greenhouses for the production of healthy seed tubers. Plants propagated from tubers are clones of the parent, whereas those propagated from seed produce a range of different varieties.
There are about 5,000 potato varieties worldwide. Three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile, and Colombia. They belong to eight or nine species, depending on the taxonomic school. Apart from the 5,000 cultivated varieties, there are about 200 wild species and subspecies, many of which can be cross-bred with cultivated varieties. Cross-breeding has been done repeatedly to transfer resistances to certain pests and diseases from the gene pool of wild species to the gene pool of cultivated potato species. Genetically modified varieties have met public resistance in the United States and in the European Union.  
The major species grown worldwide is Solanum tuberosum (a tetraploid with 48 chromosomes), and modern varieties of this species are the most widely cultivated. There are also four diploid species (with 24 chromosomes): S. stenotomum, S. phureja, S. goniocalyx, and S. ajanhuiri. There are two triploid species (with 36 chromosomes): S. chaucha and S. juzepczukii. There is one pentaploid cultivated species (with 60 chromosomes): S. curtilobum. There are two major subspecies of Solanum tuberosum: andigena, or Andean and tuberosum, or Chilean.  The Andean potato is adapted to the short-day conditions prevalent in the mountainous equatorial and tropical regions where it originated the Chilean potato, however, native to the Chiloé Archipelago, is adapted to the long-day conditions prevalent in the higher latitude region of southern Chile. 
The International Potato Center, based in Lima, Peru, holds an ISO-accredited collection of potato germplasm.  The international Potato Genome Sequencing Consortium announced in 2009 that they had achieved a draft sequence of the potato genome.  The potato genome contains 12 chromosomes and 860 million base pairs, making it a medium-sized plant genome.  More than 99 percent of all current varieties of potatoes currently grown are direct descendants of a subspecies that once grew in the lowlands of south-central Chile.  Nonetheless, genetic testing of the wide variety of cultivars and wild species affirms that all potato subspecies derive from a single origin in the area of present-day southern Peru and extreme Northwestern Bolivia (from a species in the Solanum brevicaule complex).    The wild Crop Wild Relatives Prebreeding project encourages the use of wild relatives in breeding programs. Enriching and preserving the gene bank collection to make potatoes adaptive to diverse environmental conditions is seen as a pressing issue due to climate change. 
Most modern potatoes grown in North America arrived through European settlement and not independently from the South American sources, although at least one wild potato species, Solanum fendleri, naturally ranges from Peru into Texas, where it is used in breeding for resistance to a nematode species that attacks cultivated potatoes. A secondary center of genetic variability of the potato is Mexico, where important wild species that have been used extensively in modern breeding are found, such as the hexaploid Solanum demissum, as a source of resistance to the devastating late blight disease.  Another relative native to this region, Solanum bulbocastanum, has been used to genetically engineer the potato to resist potato blight. 
Potatoes yield abundantly with little effort, and adapt readily to diverse climates as long as the climate is cool and moist enough for the plants to gather sufficient water from the soil to form the starchy tubers. Potatoes do not keep very well in storage and are vulnerable to moulds that feed on the stored tubers and quickly turn them rotten, whereas crops such as grain can be stored for several years with a low risk of rot. The food energy yield of potatoes—about 95 gigajoules per hectare (9.2 million kilocalories per acre)—is higher than that of maize (78 GJ/ha or 7.5 × 10 ^ 6 kcal/acre), rice (77 GJ/ha or 7.4 × 10 ^ 6 kcal/acre), wheat (31 GJ/ha or 3 × 10 ^ 6 kcal/acre), or soybeans (29 GJ/ha or 2.8 × 10 ^ 6 kcal/acre). 
There are close to 4,000 varieties of potato including common commercial varieties, each of which has specific agricultural or culinary attributes.  Around 80 varieties are commercially available in the UK.  In general, varieties are categorized into a few main groups based on common characteristics, such as russet potatoes (rough brown skin), red potatoes, white potatoes, yellow potatoes (also called Yukon potatoes) and purple potatoes.
For culinary purposes, varieties are often differentiated by their waxiness: floury or mealy baking potatoes have more starch (20–22%) than waxy boiling potatoes (16–18%). The distinction may also arise from variation in the comparative ratio of two different potato starch compounds: amylose and amylopectin. Amylose, a long-chain molecule, diffuses from the starch granule when cooked in water, and lends itself to dishes where the potato is mashed. Varieties that contain a slightly higher amylopectin content, which is a highly branched molecule, help the potato retain its shape after being boiled in water.  Potatoes that are good for making potato chips or potato crisps are sometimes called "chipping potatoes", which means they meet the basic requirements of similar varietal characteristics, being firm, fairly clean, and fairly well-shaped. 
The European Cultivated Potato Database (ECPD) is an online collaborative database of potato variety descriptions that is updated and maintained by the Scottish Agricultural Science Agency within the framework of the European Cooperative Programme for Crop Genetic Resources Networks (ECP/GR)—which is run by the International Plant Genetic Resources Institute (IPGRI). 
Dozens of potato cultivars have been selectively bred specifically for their skin or, more commonly, flesh color, including gold, red, and blue varieties  that contain varying amounts of phytochemicals, including carotenoids for gold/yellow or polyphenols for red or blue cultivars.  Carotenoid compounds include provitamin A alpha-carotene and beta-carotene, which are converted to the essential nutrient, vitamin A, during digestion. Anthocyanins mainly responsible for red or blue pigmentation in potato cultivars do not have nutritional significance, but are used for visual variety and consumer appeal.  In 2010, potatoes were bioengineered specifically for these pigmentation traits. 
Genetic research has produced several genetically modified varieties. 'New Leaf', owned by Monsanto Company, incorporates genes from Bacillus thuringiensis, which confers resistance to the Colorado potato beetle 'New Leaf Plus' and 'New Leaf Y', approved by US regulatory agencies during the 1990s, also include resistance to viruses. McDonald's, Burger King, Frito-Lay, and Procter & Gamble announced they would not use genetically modified potatoes, and Monsanto published its intent to discontinue the line in March 2001. 
Waxy potato varieties produce two main kinds of potato starch, amylose and amylopectin, the latter of which is most industrially useful. BASF developed the Amflora potato, which was modified to express antisense RNA to inactivate the gene for granule bound starch synthase, an enzyme which catalyzes the formation of amylose.  Amflora potatoes therefore produce starch consisting almost entirely of amylopectin, and are thus more useful for the starch industry. In 2010, the European Commission cleared the way for 'Amflora' to be grown in the European Union for industrial purposes only—not for food. Nevertheless, under EU rules, individual countries have the right to decide whether they will allow this potato to be grown on their territory. Commercial planting of 'Amflora' was expected in the Czech Republic and Germany in the spring of 2010, and Sweden and the Netherlands in subsequent years.  Another GM potato variety developed by BASF is 'Fortuna' which was made resistant to late blight by adding two resistance genes, blb1 and blb2, which originate from the Mexican wild potato Solanum bulbocastanum.   In October 2011 BASF requested cultivation and marketing approval as a feed and food from the EFSA. In 2012, GMO development in Europe was stopped by BASF.  
In November 2014, the USDA approved a genetically modified potato developed by J.R. Simplot Company, which contains genetic modifications that prevent bruising and produce less acrylamide when fried than conventional potatoes the modifications do not cause new proteins to be made, but rather prevent proteins from being made via RNA interference.   
The potato was first domesticated in the region of modern-day southern Peru and northwestern Bolivia  by pre-Columbian farmers, around Lake Titicaca.  It has since spread around the world and become a staple crop in many countries.
The earliest archaeologically verified potato tuber remains have been found at the coastal site of Ancon (central Peru), dating to 2500 BC.   The most widely cultivated variety, Solanum tuberosum tuberosum, is indigenous to the Chiloé Archipelago, and has been cultivated by the local indigenous people since before the Spanish conquest.  
According to conservative estimates, the introduction of the potato was responsible for a quarter of the growth in Old World population and urbanization between 1700 and 1900.  In the Altiplano, potatoes provided the principal energy source for the Inca civilization, its predecessors, and its Spanish successor. Following the Spanish conquest of the Inca Empire, the Spanish introduced the potato to Europe in the second half of the 16th century, part of the Columbian exchange. The staple was subsequently conveyed by European mariners to territories and ports throughout the world. The potato was slow to be adopted by European farmers, but soon enough it became an important food staple and field crop that played a major role in the European 19th century population boom.  However, lack of genetic diversity, due to the very limited number of varieties initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland as well as parts of the Scottish Highlands, resulting in the crop failures that led to the Great Irish Famine.  Thousands of varieties still persist in the Andes however, where over 100 cultivars might be found in a single valley, and a dozen or more might be maintained by a single agricultural household. 
|Potato production – 2018|
|Country||Production (millions of tonnes)|
|Source: FAOSTAT of the United Nations |
In 2018, world production of potatoes was 368 million tonnes, led by China with 27% of the total (table). Other major producers were India, Russia, Ukraine and the United States. It remains an essential crop in Europe (especially northern and eastern Europe), where per capita production is still the highest in the world, but the most rapid expansion over the past few decades has occurred in southern and eastern Asia.  
A raw potato is 79% water, 17% carbohydrates (88% is starch), 2% protein, and contains negligible fat (see table). In a 100-gram ( 3 1 ⁄2 -ounce) portion, raw potato provides 322 kilojoules (77 kilocalories) of food energy and is a rich source of vitamin B6 and vitamin C (23% and 24% of the Daily Value, respectively), with no other vitamins or minerals in significant amount (see table). The potato is rarely eaten raw because raw potato starch is poorly digested by humans.  When a potato is baked, its contents of vitamin B6 and vitamin C decline notably, while there is little significant change in the amount of other nutrients. 
Potatoes are often broadly classified as having a high glycemic index (GI) and so are often excluded from the diets of individuals trying to follow a low-GI diet. The GI of potatoes can vary considerably depending on the cultivar or cultivar category (such as "red", russet, "white", or King Edward), growing conditions and storage, preparation methods (by cooking method, whether it is eaten hot or cold, whether it is mashed or cubed or consumed whole), and accompanying foods consumed (especially the addition of various high-fat or high-protein toppings).  In particular, consuming reheated or cooled potatoes that were previously cooked may yield a lower GI effect. 
In the UK, potatoes are not considered by the National Health Service (NHS) as counting or contributing towards the recommended daily five portions of fruit and vegetables, the 5-A-Day program. 
This table shows the nutrient content of potatoes next to other major staple foods, each one measured in its respective raw state, even though staple foods are not commonly eaten raw and are usually sprouted or cooked before eating. In sprouted and cooked form, the relative nutritional and anti-nutritional contents of each of these grains (or other foods) may be different from the values in this table. Each nutrient (every row) has the highest number highlighted to show the staple food with the greatest amount in a 100-gram raw portion.
|Nutrient||Maize (corn) [A]||Rice, white [B]||Wheat [C]||Potatoes [D]||Cassava [E]||Soybeans, green [F]||Sweet potatoes [G]||Yams [Y]||Sorghum [H]||Plantain [Z]||RDA|
|Vitamin C (mg)||0||0||0||19.7||20.6||29||2.4||17.1||0||18.4||90|
|Thiamin (B1) (mg)||0.39||0.07||0.30||0.08||0.09||0.44||0.08||0.11||0.24||0.05||1.2|
|Riboflavin (B2) (mg)||0.20||0.05||0.12||0.03||0.05||0.18||0.06||0.03||0.14||0.05||1.3|
|Niacin (B3) (mg)||3.63||1.6||5.46||1.05||0.85||1.65||0.56||0.55||2.93||0.69||16|
|Pantothenic acid (B5) (mg)||0.42||1.01||0.95||0.30||0.11||0.15||0.80||0.31||-||0.26||5|
|Vitamin B6 (mg)||0.62||0.16||0.3||0.30||0.09||0.07||0.21||0.29||-||0.30||1.3|
|Folate Total (B9) (μg)||19||8||38||16||27||165||11||23||0||22||400|
|Vitamin A (IU)||214||0||9||2||13||180||961||138||0||1,127||5,000|
|Vitamin E, alpha-tocopherol (mg)||0.49||0.11||1.01||0.01||0.19||0||0.26||0.39||0||0.14||15|
|Vitamin K1 (μg)||0.3||0.1||1.9||1.9||1.9||0||1.8||2.6||0||0.7||120|
|Saturated fatty acids (g)||0.67||0.18||0.26||0.03||0.07||0.79||0.02||0.04||0.46||0.14||minimal|
|Monounsaturated fatty acids (g)||1.25||0.21||0.2||0.00||0.08||1.28||0.00||0.01||0.99||0.03||22–55|
|Polyunsaturated fatty acids (g)||2.16||0.18||0.63||0.04||0.05||3.20||0.01||0.08||1.37||0.07||13–19|
A raw yellow dent corn
B raw unenriched long-grain white rice
C raw hard red winter wheat
D raw potato with flesh and skin
E raw cassava
F raw green soybeans
G raw sweet potato
H raw sorghum
Y raw yam
Z raw plantains
Potato varieties have a wide range of skin colors including white, tan, yellow, pink, red, purple and blue. The flesh also has a wide range of colors including white, yellow, pink, purple and blue.
Potatoes are prepared in a variety of ways including roasted, fried, boiled, steamed and baked. Dishes made with them include stuffed patties, dumplings, casseroles, pancakes, salads and stews.
Like peppers, tomatoes and eggplants, potatoes are a member of the nightshade family in the genus Solanum. Many members of this genus contain dangerous glycoalkaloids that can be found in the vegetation and fruiting parts of the plant. The potato tuber contains negligible levels of these compounds however, if exposed to sunlight for a prolonged period they can increase to levels that may be harmful to human health. You will see throughout this guide we take steps to shelter the tubers from exposure to sunlight in both the growing stage and storage stage.
The potatoes for sale in the grocery store represent only a very small portion of the types and varieties of potatoes available. The marketplace is not geared to offer you 20-30 different varieties. The best way to experience the diversity of potatoes is to grow your own.
Potatoes can be placed in three general categories depending on what type of flesh the tubers have: starchy, waxy or all purpose. Although they have many different skin and flesh colors, these different colors do not indicate potato type--skin and flesh color cuts across the board of potato types. Fingerlings and low glycemic varieties are subcategories.
Starchy varieties have white to pale yellow flesh that has a dry, light, fluffy texture when cooked. They break down during the cooking process and do not retain their shape. Excellent for baked potatoes, light and fluffy mashed potatoes and french fries. Russet potatoes are the most common starchy varieties. They are medium to large potatoes with a russeted brown netted skin. 'Russet Burbank' is a classic high starch variety.
Waxy potatoes have a firm creamy texture, high moisture content and hold their shape when cooked. They work great for boiling, roasting and baking when you want the potato to retain its shape. They are also good for soups and potato salads. 'Carola', a favorite among home gardeners, is an old German waxy variety that stands the test of time.
All-purpose potatoes come in many skin colors and flesh colors. They have moderate starches and moisture and are good for most culinary uses. Think of all-purpose potatoes as the ultimate workhorse. As the middle of the road potato, all-purpose potatoes usually suffice as a substitute for any starchy or waxy potato recipe. The most well-known is 'Yukon Gold'.
Fingerlings are usually 2-4 inches long and have various skin colors including tan, red, yellow and purple. Flesh color varies as well. They have a firm, waxy texture and buttery, nutty and earthy flavors. Pan frying and roasting are great ways to feature their buttery flavor. They also work great in potato salads and stews. 'French Fingerling' and 'Russian Banana' are well-known varieties.
Potatoes have long been on the list of high glycemic foods. High glycemic foods are digested quickly and can cause a big spike in blood sugar and insulin levels. Low glycemic index (GI) foods digest slowly and do not cause a large spike. Recent research has revealed the variety 'Nicola' is a low GI potato.
Potatoes are packed with nutrients. Among them are fiber and antioxidants. The fiber helps control cholesterol and blood sugar levels, provide good bacteria for gut health and otherwise promote digestion and regularity. If your doctor has advised eating food with a low glycemic index to prevent spikes in blood sugar or glucose levels, choose a potato variety identified as low glycemic. The antioxidants in potatoes help prevent cell damage, which is believed to help reduce the risk of heart disease and cancer. In a potato, the highest levels of antioxidants are in the skins, so be sure to eat the skins. Among the different varieties of potatoes, the highest levels of antioxidant are found in those with color, such as purple potatoes. Potatoes are also a source of vitamins C and B6, potassium, magnesium and even calcium. Potatoes often get a bad rap, but in addition to their nutritional value, they are actually a fat- and cholesterol-free food—it's how you cook them or dress them that causes problems.
When buying potatoes for planting, whether conventional or certified organic, always make sure they are certified disease-free potatoes from a reputable source. Avoid grocery-store potatoes, which are often treated with a chemical that inhibits sprouting.
Potato plants grow best in loose soil that is well drained and located in full sun. Unless you live in a warm climate, do not follow the adage of planting potatoes on St. Patrick's Day. If planted too early, wet soil will delay emergence or cause the tubers to rot. The soil temperature should be 50°F or higher, often reached two to three weeks before the last spring frost. In many areas, the general rule is potatoes can be planted when dandelions start to bloom.
Green sprouting, or chitting, warms seed potatoes to encourage sprouting. Although not required, it does promote quicker soil emergence, earlier harvest and may increase yields. It also lets you get a head start on the gardening season by giving you a task that can be done inside while the weather is still too inclement for planting. Follow these steps to green sprout:
Potato plants are fairly frost tolerant however, a hard freeze can burn them to the ground. They can recover, but you will lose time and yield. If a hard freeze is predicted, protect your plants with frost blankets or something similar.
Having a sample of your garden soil tested for fertility is a good way to start your growing season and will give you a baseline for fertilization. Potatoes prefer a well-drained soil with a pH range of 6-7. They are adaptable, however, and can be grown outside this range.
Fertilize at time of planting
Fertilize again when flowers appear
Potatoes can be fertilized at time of planting or just as their sprouts emerge from the ground and again at midseason just as the potatoes begin to flower. Gurney's® Potato Food-Fertilizer is a good blend. It not only provides the nutrients potatoes need, it feeds the microbes that unlock other nutrients in the soil.
Once plants are 8-10 inches tall, it is common practice to pull soil up onto each potato plant from both sides of the row. This can be done every two to three weeks until the hill is 8-12 inches tall. Hilling accomplishes several tasks. It helps with weed control and keeps tubers covered so they do not turn green from direct sunlight. For indeterminate varieties, it will boost yields since the covered stems can produce more potatoes. Determinate potatoes only need a few inches of soil when hilling to make sure the tubers are covered and protected from sun exposure.
Mulching the potatoes is a good practice especially if you do not intend to hill your potatoes. The mulch helps keep consistent moisture and does not allow sunlight to hit tubers that are at the surface. The sunlight will turn the skin green, and this is not beneficial to you or the tuber.
Maintaining consistent moisture will benefit both the quality and quantity of potatoes harvested. Proper moisture is particularly important when tubers are forming. They start forming about the same time as the plants start to bloom. Avoid overly wet conditions as this could lead to disease problems.
Once potatoes have had their final mulching or hilling, the main task is to keep them well watered and free of pests until a few weeks before harvest time.
Hilling helps control weeds and keeps tubers covered so they do not turn green from exposure to the sun.
Growing potatoes in containers is an excellent way to produce clean, blemish-free tubers from healthy plants. It is an ideal method if you have limited space or want to get a jump on the season. Many of the same guidelines for growing potatoes in the ground pertain to container growing. Short season determinate varieties work best in containers however, any variety will work. I grow most of my potatoes in ground although I do plant a few containers of red potatoes for harvesting small new potatoes early in the season. Container-grown potatoes seem to mature faster since the soil warms quicker.
Select a large container: 15-20 gallon pots or grow bags are a good size. Use a good, free draining potting soil. You can amend the potting soil with some compost if it is available. Do not use garden soil. Fill the container with 4-6 inches of soil. Place 4 or 5 cut potato pieces or small potatoes equally spaced on top of the soil. Once potatoes are placed, top off the pot and bring the soil level up just below the pot rim. Work some fertilizer into the mix and water.
Once the potatoes start growing, keep the mix consistently moist. Since they are in a pot and being watered often, nutrients leach out of the pot. To counteract this, use a diluted liquid fertilizer every two weeks or sprinkle more granular fertilizer once a month. Hilling is unnecessary however, mulching may be helpful to maintain moisture.
Potato plants are fairly frost tolerant however, a hard freeze can burn them to the ground. They can recover, but you will lose time and yield. If a hard freeze is predicted, protect your plants with frost blankets or something similar.
A high-quality fertilizer like Gurney's® Potato Food-Fertilizer helps ensure successful yields.
Hilling helps control weeds and keeps tubers covered so they do not turn green from exposure to the sun.
Growing in raised beds is very similar to growing in a container. One important consideration when planting in a raised bed is soil quality. If it is light and fluffy, the potatoes can be planted 4-6 inches deep. If it is more like garden soil, stick to planting 2 inches deep. Other than that, follow the standard guidelines for growing potatoes.
For new small potatoes, you can start checking roughly three weeks after the plants start flowering. To do this, carefully pull soil away from the plant near where the stem meets the soil. Start harvesting when the tubers are about the size of a golf ball. For storage purposes, potatoes are ready to harvest two weeks after the vines turn yellow and die down. This period in the ground after plants die allows the skin on the potatoes to cure or toughen and enables the potatoes to store better without the skin getting blemished.
When your potatoes are ready to dig, use a shovel or digging fork to loosen soil on either side of the row, starting about 12 inches out from the plant base. Push your tool into the soil at an angle towards the center of the row, getting underneath the potato plant. Once the tool is inserted, gently use leverage to pry up and loosen the soil. When soil is loosened around the plant, reinsert your tool and lift up to expose the tubers. Do this several times and sift through the soil until you find all the potatoes. As you get a feel for the location of the tubers, adjust you digging distance and depth accordingly.
Potatoes that have been damaged by the digging process should be eaten right away since they will rot quickly in storage.
After harvesting, do not wash the potatoes before storing however, you can brush off the dirt. Store potatoes in a cool, humid and dark place. The ideal temperature range is 42-50°F. A warm environment encourages sprouting. If the environment is too cold, tissue damage will occur. A root cellar would be perfect however, since most of us do not have one, try a cool corner of the basement or unheated garage.
Potatoes are generally an easy crop to raise however, there are a few pests and diseases that the home gardener should keep in mind since a few can have dramatic effects on plant health and yield.
Crop rotation is a good practice to help avoid several pests and diseases. Always plant high quality seed potatoes and never plant potatoes in the same spot as they were grown the year prior. Avoid planting them where other members in the nightshade family have been planted. These include tomatoes, peppers, eggplants and tomatillos. Also, try to keep weeds in the nightshade family out of the garden and surrounding areas. Jimson weed, nightshade, horse nettle and ground cherries are some of the main weeds to watch for.
The Colorado potato beetle is the most common pest on potatoes and quite easy to spot when it is feeding. Both larvae and adults feed on potatoes and can completely defoliate the plants. There are several strategies the home gardener can use to prevent damage from this pest.
Exclusion is a good first course. Covering the row with Super-Lite Insect Barrier will keep the beetles and other pests from getting on the plants. Another good option is Surround at Home® Kaolin Clay Crop Protectant. When these fine clay particles are sprayed onto the plant, insects spend all their time being irritated and try to clean themselves instead of eating your plants.
In the small garden you can physically pick the larvae and adults off the plants. If you see egg masses under the leaves, you can pick them off, too. To prevent eggs from hatching, Oil-Away™ Supreme Insecticidal Oil can be sprayed to smother eggs without harming beneficial insects. For larvae and adults, Pyola® Insect Spray is a good option for knocking them back. Shield-All Plus™ Pest & Disease Control will address insects and disease problems.
Flea beetles are another nuisance. Often their damage is superficial and does not affect yield however, if numbers get large, they can do some serious damage. Most of the methods mentioned above for the Colorado potato beetle work for flea beetles as well.
hoppers are sucking insects, and their damage is first noticed as pale coloring along the leaf veins, followed by browning of the leaf tips. If not controlled, they can reduce potato production. It is best to deal with them early. The same controls for Colorado potato beetle can be used for potato leaf hoppers.
Aphids are another sucking insect that can do great damage to your potato crop. As with the leafhoppers, it is much easier to deal with them early before crop damage and a population explosion that comes with warmer weather.
The Colorado potato beetle can completely defoliate plants.
Browning leaves are a sign of potato leaf hoppers.
Aphids can also do great damage to your potatoes.
Damage from flea beetles is superficial unless there is an infestation.