As forest conversion to agriculture and pasture lands are intensified in the Peruvian Amazon, so is the intentional use of fire, according to scientists with the Center for International Forestry Research. Because fields become overgrown quickly in the tropics, oil palm planters, farmers and cattle ranchers burn fields to clear weeds and set fires in pastures to eliminate ticks that annoy livestock. Problems arise when the wind whips a fire out of control and endangers the surrounding forest.