Glyphosate

Chemistry and mode of action

Chemically, glyphosate interferes with the shikimate pathway by inhibiting the enzyme 5‑enolpyruvylshikimate‑3‑phosphate (EPSP) synthase. This pathway is essential for the biosynthesis of certain amino acids in plants and some microorganisms; it is absent in animals, which partly explains the herbicide's selective biological target. Glyphosate is systemic: it is absorbed by leaves and translocated through the plant to growing points.

History and development

Discovered and commercialized in the 1970s, glyphosate became one of the most widely used herbicides worldwide. Its adoption increased after the introduction of genetically modified, glyphosate‑tolerant crops in the 1990s, which allowed farmers to apply glyphosate for weed control without damaging the crop. Over decades, many manufacturers have produced formulations that combine glyphosate with surfactants and other adjuvants to improve absorption and spreading.

Uses and examples

Applications include pre‑plant and post‑emergent weed control in row crops, vineyard and orchard floor management, roadside and rights‑of‑way maintenance, and invasive aquatic weed control. It is also used as a desiccant for crop drying in some systems. Common practical considerations are timing, dose, and formulation choice; users often consult product labels or manufacturer guidance for specific application details: product information.

Safety, regulation and controversy

Glyphosate has been the subject of extensive toxicological and epidemiological study. Some organizations and independent reviews have concluded there is potential for carcinogenicity or other health risks under certain exposures; other national or regional regulatory authorities have found that, when used according to label instructions, glyphosate does not pose an unacceptable risk to human health. Formulations vary and co‑formulants (such as surfactants) can influence environmental behavior and biological effects. For summaries of regulatory assessments and differing conclusions see relevant review sources: regulatory reviews.

Environmental effects and resistance

Environmental considerations include persistence in soil and water, effects on non‑target plants and microorganisms, and the role of formulations in aquatic toxicity. A major agronomic challenge has been the evolution of glyphosate‑resistant weed populations in many cropping systems, which has prompted integrated weed‑management strategies combining cultural, mechanical and chemical controls. Ongoing monitoring, stewardship and research aim to balance the herbicide's agronomic benefits with environmental protection and public health considerations.