acetolactate synthase agent orange agent pink agent purple agriculture amino acid aminopyralid apicoplast atrazine australian railway history auxin bioherbicide chlorophyll citrus clopyralid cultural controls dl-phosphinotricin dicamba ester flame glyphosate habitat imazapyr isoleucine leucine limonene list of environmental health hazards mechanism of action metolachlor organic farming paraquat pendimethalin pentachlorophenol pesticide application pesticide toxicity to bees phenylalanine picloram plant plasmodium falciparum plastid polychlorinated biphenyl polychlorinated dibenzodioxins preemergent herbicides rainbow herbicides roundup soil contamination spice steam surface runoff triclopyr trimethylamine tryptophan tyrosine united states valine vegetation vietnam war vinegar walnut weed