Cultivating and storing the potato

The cultivation of the potato in the Andes

The Incas cultivated the potato after fallowing, it's still the case today. The potato is cultivated at a high altitude to remedy the recurrent phenomenon of degenerating tubers.

On Midsummers Day, at an altitude above 2000 m, the "papa imilla "and the" papa runa" are planted. They are planted in small densly grouped furrows to retain irrigation water. Above 2500 m, the land is worked at the end of July, and corn is immediately sown, along with row beans and edible gourds. Between 2500 and 3500 m, during Febuary, the "papa pureja" is planted on unirrigated land, these are harvested in May.

The 300 varieties of potato grown originally in the region of lake Titicaca are cultivated at an altitude of between 3000 to 4800 m. The best tubers are cut into quarters, with one to three eyes, these are planted during a descending moon at a high altitude, because under 3000 m, they grow badly and degenerate. They are stored in houses, in conical piles on bamboo racks on the floor. Muna leaves (insecticidal plant with an odour of mint) are placed under the racks , also slices of Isaño (a tuber with an acrid smell) or small acidic apples to repel worms.

Chuño, tunta and papa seca :

At an altitude above 4000 m up to 4800 m, the bitter potato, which is very frost resistant is cultivated. It is eaten by transforming it into chuño after its bitterness is removed. The tubers are succesively exposed to the repeated actions of frost and sun, then they are dried and stored during months, even years. This technique pre-dates freeze drying.

To prepare tunta, average potatoes are chosen and are exposed to the frost for 2 or 3 nights. The tubers are then put into jute sacks and plunged down a well during 15 to 20 days. When they are dried the tubers turn a white colour.

The papa seca is a cooked potato, peeled and exposed to the frost for some days.

A customary Andean recipe :

Soak the tunta about an hour in water, and the chuño for one night. When the potatoes are soft, pull them into 4 or 6 pieces with your fingers. Cook them in water. Mix the potatoes with fresh grated cheese. The chuño can also be cooked with other vegetables and mixed with aromatic herbs to make flat cakes (galettes).

The cultivation of the potato in France

The potato is reproduced by planting whole tubers, fragments, cuttings or seedlings. The use of certified plants guarantees that they will be disease free.

Inderterminate clonal reproduction causes physiological aging, a degeneration of potatoes, even their disapperance. The old varieties are now regenerated by in-vitro rooting of microcuttings by the I.N.R.A. in France.

The best crops are obtained in a light, humus rich, deep soil, after a 'green' fertiliser. The potato likes potash, but detests an excess of fertiliser and nitrogen. Use 'house' compost enriched with wood ash.

Avoid planting potatoes in the same place twice running. Equally avoid planting with other solanaceaes like the aubergine or the tomato. It is better to plant potatoes that have "eyes". The potatoes will have been stored in a cool and light, frost-free place, on shelves. Planting is made in holes 10 to 15 cm deep, 40 to 50 cm apart in rows with a hoe or spade. The rows should have a distance between them of 60 to 70 cm. Potatoes develop above the seed, drawing up the soil around the stems 'ridging' as the plants grow is vital. Hoe between the rows from time to time to aerate the soil and remove weeds.

Harvesting and storing potatoes

Harvesting of potatoes is done once the vegetation has completly withered. Leave them to dry for a few days on the soil, by losing a part of their water they keep better, and then place them for 2 weeks in a dark, temperate place to avoid grening. Afterwards store in a cellar or cool dark place.

To keep potatoes for a long time choose varieties that are late or semi-late, store them in a cool, dark place away from frost, damp and rodents. Crushed charcoal sprinkled on the tubers will delay germination 'sprouting'. They can also be buried in dry sand. For larger quantitites a silo can be made.

Diseases and parasites of potatoes

Blight is caused by a microscopic fungus, it's the combined effects of heat and humidity which causes its appearance. Yellow marks, then brown, appear firstly on the leaves, afterwards they have a burnt apperance, lastly the tubers are affected. A preventative treatment is to spray with a Bordeaux mixture from mid-June. Planting horseradish nearby creates a favourable environment.

The Colorado Beetle is a yellow and red beetle that has the ability to reproduce three times a year.The eggs are laid on the underside of the leaves and are yellow, the larvae turn red. Treatment must be applied rapidly because in a few days all the foliage can be eaten and the plant destroyed. Spray with a Bordeaux mixture and rotenone.

The degeneration of tubers is related directly to a loss of yield. After some years of consectutive cultivation, the planting of old varieties becomes impossible. This is why we lose a number of old varieties of potatoes every year, these are exhibited at the potato festival.

It is possible to regenerate certain varieties by a Dutch method of selection, or by the 'midchourinienne' method.

The Dutch method is to select the best leafy plants with the aid of a stick, and dig  them up before full maturity. Those that have a high yield at harvesting, with well formed tubers, are exposed to the weather during 30 to 4O days on the same soil. The tubers become green ( almost black) and pass on to their offshoots all their good qualities.

The 'midchourinienne method' consists of leaving the tubers in the atmospheric conditions of their country of origin. They come into vegetation when the Colorado Beetle has come to the end of its reproduction cycle. This system is difficult the first year as the plant must be kept until the growing season in July. Do not kill the Colorado Beetle when it is "sterile", this way the plants can form their natural defence system and become resistant to insects. This is used in production in the Puy de Dôme, at Saint-Anthème at an altitude of 1300 m, there is the Vitelotte Noire, Bleue d'Auvergne, Ratte (or Corne de Mouton), early Cornichon, Misterlé, Quenelle de lyon, Ranée...etc.