Farmers can use the pesticide dicamba to clear fields of stubborn weeds for two more growing seasons after the EPA on Oct. 31 extended the temporary approval of new versions of the chemical, which is prone to drifting off-field.

“EPA understands that dicamba is a valuable pest control tool for America’s farmers,” Andrew Wheeler, acting administrator of the Environmental Protection Agency, said in a statement. “By extending the registration for another two years with important new label updates that...