DUO, a weed chemical combining glyphosate and 2-4D, has been re-approved by the US Drug Authority.
In 2014, groups opposing the use of farm chemicals forced a re-appraisal of the chemical made by Dow.
It has still been available in the USA and Australia, but with extra handling warnings.
But, after further independent tests, USDA has approved it for use on farms and public spaces (eg, road verges).
The chemical mix is popular because it is effective on grasses and woody or deep-rooted weeds.