BOGOTÁ, Colombia—Aerial fumigation of drug crops, a centerpiece in the U.S. war on drugs in the Andes, is close to being phased out after Colombia’s president on Saturday publicly said he is recommending ending its use against the leaf used to make cocaine.

Since the 1990s, aerial spraying, undertaken by crop dusters dropping the defoliant glyphosate on coca fields in much of Colombia, has been eagerly pursued by three U.S. administrations that saw it as the best way to deliver a blow against drug trafficking here.

...