Herbicide Resistant Weeds and Crops

Modern herbicidal weed control often exploits physiological differences among plants and takes advantage of herbicide tolerance or resistance in crop plants to bring about the selective removal of susceptible weeds. The Weed Science Society of America defines herbicide tolerance as “the inherent ability of a plant to survive and reproduce after herbicide treatment” which suggests that herbicide-tolerant plants have a natural level of tolerance not due to selection or genetic manipulation. In contrast, herbicide resistance is defined as “the inherited ability of a plant to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type”. This definition includes both naturally occurring cases of evolved resistance and those resulting from genetic engineering, mutagenesis or in-vitro techniques.