What is herbicide selectivity ?
Plants that can rapidly degrade or deactivate a herbicide can escape that herbicide’s toxic effects. Corn is tolerant to the triazine herbicides because it quickly deactivates these herbicides by binding them to naturally occurring plant chemicals. Soybean tolerance to metribuzin (Sencor, Lexone) is at least partially due to the deactivation of the herbicide by conjugating (i.e., binding) to plant sugar molecules. Situations may occur in which a crop may be injured by a herbicide to which it is normally tolerant. This often occurs because environmental stresses such as hot or cold temperatures, high relative humidity, or hail decrease a plant’s natural ability to reduce herbicide uptake or deactivate a herbicide. Postemergence cyanazine (Bladex) injury to corn under cold and wet weather conditions is a good example of environmentally induced herbicide injury. An excessive application of herbicide, due to misapplication, can also injure a tolerant crop by overwhelming the crop’s herbici
