Peru: They have quarreled over the 1880's pillaging of Peru's national library by Chilean troops. They have squabbled over who has the naming rights to pisco, the fiery grape brandy. Now, Peru and Chile are arguing over another hot-button issue: the origins of the potato. Peruvian agronomists, historians and diplomats are chafing at an assertion by Marigen Hornkohl, Chile's agriculture minister, who said on Monday, "Few people know that 99% of the world's potatoes have some type of genetic link to potatoes from Chile.' Peru, where the potato is a source of national pride, could not let such a comment pass. "Obviously the world has known for centuries that the potato is from Peru and that the Peruvian potato saved Europe from hunger,' foreign minister Jose Antonio Garcia Belaunde said. "The entire world knows this.' And if some parts of the world did not know of the importance of Peru's potatoes, Peru is attempting to remedy that through events organized here around the International Year of the Potato, decreed as such by the UN to promote potato's role in easing food shortages in poor countries. Chileans gain comfort from studies showing that more than 90% of the modern potato varieties outside the Andes have a common origin in potatoes once found in the area around Chiloe Island in southern Chile region. Potatoes from Chiloe found their way to Europe, where they were well suited to latitudes with longer days. But potato experts here