Introducing genes for herbicide resistance into a crop permits it to be sprayed with weedkiller that really does then kill nothing but weeds.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/silence-please
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/economist-london
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/agriculture
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/gm-crops
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/herbicide
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rice
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/farmers
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/china