The 7th World Potato Congress was held in New Zealand last month. Andrew Swallow reports

History proved the potato’s population-sustaining potential and the crop would play a key role in feeding the world in future, delegates to the recent WPC in Christchurch heard.

A string of speakers stressed the nutritional value of the crop, its high production level across a wide range of climates and soils, and efficient water use.

But, as US author and historian Larry Zuckerman told the congress, it took centuries for the western world to wake up to those benefits.

“If replanted they grew,” he said. “That was unknown in Europe previously: the Devil’s work surely?”

Categorisation as a solanum, the same family as tobacco, a narcotic, and deadly nightshade, a poison, did little for potatoes’ nutritional reputation, nor did rumours of a link with leprosy or poisoning land, so subsequent cereal crops failed.

It was only when political forces came to bear on Europe’s population, such as the French revolution and Britain’s rule in Ireland, that potatoes started to become widely grown as a food crop.

Spuds supported the ballooning Irish population on small, rented farms, while wealthy landlords – usually British – harvested cereals off the bulk of the estates.

Even during the infamous famine of 1845-6, when, in a population of 2.8m, 1m died and 1.3m emigrated, grain was exported.

Fellow speaker Jim Bolger, prime minister of New Zealand 1990-1997 and chair of the World Agricultural Forum‘s advisory board in St Louis, said that held lessons today.

It showed how potatoes could support a large population off a limited area, highlighted the danger of over-reliance on a few varieties, and demonstrated how politics caused famine.

With 1bn of the world’s 6.25bn “going to bed hungry each night”, the prospect of feeding 9bn by 2050 is “daunting by any physical measure,” said Mr Bolger.

Nonetheless, he was adamant it could be done, if the political will and co-operation worldwide could be mustered.

“Without question the potato will play a major role.”

Obesity solution and hunger buster

Potatoes offer a win-win solution to the twin global challenges of malnutrition and obesity, Oxford Brookes University’s professor of human nutrition, Jeya Henry, told delegates.

The challenge for the potato industry, and indeed governments, is to get that message across and combat the many myths about potatoes that had proliferated.

Statements that potatoes are fattening are “complete nonsense” as potatoes are “nutrient-dense, not energy-dense,” he said.

A two-fingered Kit-Kat bar contained as much energy as two potatoes weighing 180g.

Satiety scores showed, per calorie, potatoes were three times as filling as white bread, and five times as filling as a Mars Bar.

Potatoes were “loaded with micronutrients” including many antioxidants, and crisps contained more vitamin C per gram than apples.

High potassium and low sodium meant they could help lower blood pressure and it was an urban myth that fried potato products were laden with fat.

High glycaemic index concerns were also unjustified. While potatoes alone had a moderately high GI, they were almost invariably eaten in a meal format which brought the GI tumbling down – or processed as crisps or chips, which also reduced the GI substantially.

A campaign of “widespread communication and advertisements to promulgate the benefits of the potato” is needed, Prof Henry concluded.

6p principle for perfect potatoes

Follow the 6P principle to grow perfect potatoes, Scottish specialist Stuart Wale told growers at the congress.

“Proper prior preparation produces perfect potatoes,” he said.

Banal as that message might be, his experience is that it had yet to be put into practice by many growers. With half or more of the quality parameters of a potato crop determined and controlled before planting, it was well worth doing, he stressed.

“You should start the process a year or two before you plan to plant a particular field.”

Crop records from previous potato crops in the proposed fields should be checked for incidence of diseases such as spraing or potato mop-top and the field tested for potential pests such as nematodes.

Potential weed problems, including volunteers from preceding crops, should also be identified.

“Oilseed rape volunteers can be particularly difficult.”

DNA soil tests for black dot and powdery scab should be considered, as should risk of other soil and seed-borne diseases based on crop interval and control of ground-keepers in between.

Target market and cultivar choice in light of the issues identified should then be considered and suitable seed sourced. Ideally, the grower, or his or her representative, should inspect the seed crop in field and again in store.

“If you wash seed it can be very revealing,” said Dr Wale.

Early delivery was advisable to gain control of pre-planting management.

Nutrient requirement based on previous cropping and soil tests should be calculated.

Growers also needed to know their own costs in detail, taking everything into account, he stressed. “That’s very important. If you don’t know what your costs are you don’t know how much you need to get from your spuds at the other end.”

A typical figure was £5000/ha (£2000/acre). “That’s a lot of money, and if you’re growing 100ha that’s a lot of risk. This whole game of potatoes is about managing risk.”