glyphosateresistant

Glyphosateresistant describes populations of plants that survive applications of glyphosate, a broad-spectrum herbicide widely used in agriculture, forestry, and home landscapes. Glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) in the shikimate pathway, preventing synthesis of aromatic amino acids. In glyphosateresistant populations, inherited genetic changes or other traits reduce the herbicide’s effectiveness, leading to control failures and potential yield losses.

Resistance arises through multiple mechanisms. Target-site resistance includes EPSPS gene amplification or mutations that reduce glyphosate binding, increasing the amount of enzyme required for effect. Non-target-site resistance includes reduced herbicide translocation, sequestration in vacuoles, enhanced metabolism, or other physiological changes that limit the herbicide’s reach or impact.

Many weed species have evolved glyphosateresistance in different regions, with notable examples such as Palmer amaranth (Amaranthus palmeri), waterhemp (Amaranthus tuberculatus), rigid ryegrass (Lolium rigidum), horseweed (Conyza canadensis), and common ragweed (Ambrosia artemisiifolia). The rapid spread is linked to repeated use of glyphosate as a single-site control tactic, along with biological traits such as high fecundity and persistent seed banks.

Management emphasizes diversification of weed-control tactics. Best practices include rotating crop and herbicide modes of action, using mixtures with complementary sites of action, integrating mechanical and cultural control, delaying reliance on glyphosate, and monitoring fields for early detection. Regulatory and research programs track resistance patterns to inform guidelines and stewardship.