Synthetic Auxins
Synthetic auxins are routinely used to control weeds. When they are used as herbicides, they are applied in higher concentrations than those at which IAA normally occurs in plants. One of the most important of the synthetic auxins used in this way is 2,4-D. It kills weeds in lawns without harming the grass because 2,4-D affects only broad-leaved dicots. When treated, the weeds literally grow to death, rapidly depleting all metabolic reserves so that there is no source of energy to carry out transport or other essential functions.
Closely related to 2,-4D is the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), which is widely used to kill woody seedlings and weeds. Notorious as the Agent Orange of the Vietnam War, 2,4,5-T is easily contaminated with a by-product of its manufacture, dioxin. Dioxin, which is believed to be harmful to people, is the subject of great encironmental concern.
แหล่งข้อมูล: Understanding Biology. Page 727.
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