How can auxin kill dandelions

The tips of the growing stems and roots apical meristem of a plant is one of the main places where auxin is produced. The apical meristem is also the location that all other parts of a plant grow from - the stem, leaves and flowers. Auxins are one specific group of hormones that are used:. Selective weedkillers kill some plants, but not others. This can be useful for getting rid of dandelions in a lawn without killing the grass or weeds that compete with crops such as wheat.

The selective weedkiller contains a growth hormone that causes the weeds to grow too quickly and die. Because most weeds have broader leaves than grass or wheat, the weedkiller is absorbed in larger quantities by the weeds.

The apical meristem is also the location that all other parts of a plant grow from - the stem, leaves and flowers. Auxins are one specific group of hormones that are used:. Selective weedkillers kill some plants, but not others. This can be useful for getting rid of dandelions in a lawn without killing the grass, or weeds that compete with crops such as wheat. The selective weedkiller contains a growth hormone that causes the weeds to grow too quickly and die.

Because most weeds have broader leaves than grass or wheat, the weedkiller is absorbed in larger quantities by the weeds. Selective weedkillers kill plants that some species of animals rely on as a food source.

This can result in a reduction of biodiversity. For an illustration of the complex effects of auxin-based herbicides on plants, see Figure 1 in the reference listed below.

Perhaps the simplest explanation for both questions has to do with sensitivity to the plant hormone auxin. In general, grasses are much less sensitive to synthetic auxin herbicides than are dicots. So, at the doses used to kill dandelions, for example, grasses are largely unaffected. Higher doses of 2,4-D may kill the grass, too, however. Grasses may be more resistant to such herbicides because of differences in leaf morphology, translocation of the herbicide inside the plant, and the ability to metabolize breakdown synthetic auxins.

Aside from the toxic contaminant dioxin, 2,4-D has no physiological effects on animals at hormonal levels, that is, at the concentrations that affect plants. Indeed, there is no reputable evidence that any of the five main plant hormones affects animals.

Reference Grossmann, K. Bottom Line: The herbicide 2,4-D mimics the plant hormone auxin and sets off a complex series of events — involving two other plant hormones — that eventually lead to the death of susceptible plants.

At hormonal levels, auxins affect plants but not people. The existing population was removed from the rural land and transferred to cities. Once the population was removed and the plants died, bare bands of earth were established on either side of main roads to reduce the opportunities for ambush.

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