A NEW form of glyphosate resistance has prompted a warning that the herbicide has ”become as important for reliable global food production as penicillin is for battling disease”.

A vigorous weed of cotton fields in the south-east United States, Palmer amaranth, has been found capable of resisting the effects of glyphosate through ”gene amplification”, the third type of resistance mechanism now discovered, and one that has rung alarm bells with researchers.