Spanish explorers brought the potato to Southern Europe by 1570. Unfortunately, the potatoes planted in Europe produced foliage and flowers but very small tubers because of the long day summer conditions. In their own creative way, botanists started taking the seeds from the berries produced by the pollination of the flowers on potato plants, and sowing those seeds. Gradually they selected for clones that could tuberize under long day conditions. This process resulted in potato varieties that were able to tuberize well under the long summer days of Europe, which contrasts sharply with the 12 hour days in the potatoes’ home country of Peru.
Potatoes were popular, spreading rapidly throughout Europe during the 1600s and early 1700s. Scholars and botanists were curious about the edible plant, and they began to study and experiment with growing potatoes. At first, monasteries used potatoes as a cheap source of food; soon, the plant was spread throughout Europe by Protestants who were moving about because of religious persecution. By the late 1700s, the potato was grown nearly everywhere in Europe. For the amount of land they need, potatoes yield an incredible amount of food. This adequate food source led to a rapid increase in Europe’s population. The good nutrition of the potato allowed people to be healthier, even lowering the mortality rate. By 1815, potatoes were the staple food for most Europeans.
From 1620, the potato spread to the USA and Canada, India and other parts of Asia and the Pacific as well as to Africa. The European colonial powers were instrumental in disseminating the potato to their colonies.
Unfortunately, the large area under cultivation had come from a narrow genetic base. Most of the varieties probably originated from self-pollinated berries selected by the botanists in Spain right after 1570.
The famous Irish potato famine of 1845 – 1846 was caused by late blight (Phytophthora Infestans). The disease came from Mexico via the USA in the form of infected tubers carried by boat passengers. Late blight first affected potatoes in Canada and the USA in 1844. One year later, the disease partially destroyed Ireland’s potato crop, and completely wiped it out in 1846 and in subsequent years. The rapid spread of late blight was in part due to the narrow genetic base of the few varieties that were grown.