Environmental organisations have turned to an old enemy, toxic agrochemicals, as an extreme measure to combat invasive plant species that are threatening native flora in conservation areas. One common case is that of Brachiaria, a species of grass used to feed livestock which hinders the growth of other plants. “Cutting it is not enough, because it always grows back,” explained Silvia Ziller, executive director of the Horus Institute, which is conducting studies with herbicides in protected areas in three Brazilian states.

Chemical weed killers are “a cheap, efficient alternative with a lesser environmental impact than the propagation of these species,” Ziller told Tierramérica.

The most recent of these experimental studies is being carried out in Emas National Park in the central state of Goiás. The measure has divided environmentalists, but the Brazilian environmental authority, IBAMA, has authorised research with toxic agrochemicals in native forests.