They have agreed to stop aerial spraying within 300 yards of lakes, bays and rivers, where more precise hand-spraying is now the rule.

ECONOMIST: Florida agriculture

Charlotte Faurie and Michel Raymond at the University of Montpellier, France, deduced the prehistoric cave painters' handedness by spraying paint against cave walls to see which hand they pressed against the wall, and therefore did not use for drawing.

BBC: Cave handprint, Montpellier University

Vice President Santos talks of this spraying being ineffective and insists the plants should be dug up by hand, and this unit was the first to do this highly dangerous work.

BBC: Transcript: Cocaine: Alex James in Colombia