Which mode of herbicide action destroys plant tissue by rupturing plant cell membranes and must be applied postemergence?

The mode of herbicide action that destroys plant tissue by rupturing plant cell membranes is referred to as a cell membrane disruptor. This type of herbicide operates by attacking the integrity of the plant's cell membranes, leading to leakage of cellular contents and ultimately causing cell death. These herbicides are typically applied postemergence because they require the target plants to be actively growing; this ensures that the herbicide can effectively penetrate and disrupt cell membranes.

Other modes of action, like growth regulators, focus on altering plant growth patterns and may not cause immediate tissue destruction, while amino acid synthesis inhibitors block specific metabolic pathways, leading to slow plant decline rather than immediate rupture of tissue. Seedling growth inhibitors target specific stages of plant development to prevent germination or early growth, but they do not necessarily rupture membranes, making them ineffective for immediate tissue destruction. Thus, the clear distinction of cell membrane disruptors delivers a direct and immediate impact on plant cells when applied at the correct growth stage.