The fight pits hardscrabble, traditional organic growers mostly in Bolivia's semi-arid highlands against upstart Peruvian agribusinesses concentrated on the Pacific coast that include heavy pesticide users. A week earlier, Bolivian authorities took 23 metric tons of Peruvian quinoa seized at a checkpoint near the border, dumped it into a ditch, soaked it with diesel fuel and burned it for TV crews — an extreme measure in a country where nearly half the people are poor and roughly one in five toddlers suffers from malnutrition. [...] Peru is on track to supplant Bolivia this year as the top exporter, having doubled production from 2013 to 95,000 metric tons amid strong demand from the U.S.