Summary - Auxin and Auxinic Herbicides - Part 1 - Introductory
The auxinic herbicides have been around since World War II and were the first selective herbicides developed. Although they continue to be a very important class of herbicides, their precise mode of action is still unknown. These herbicides are very important agrochemicals for selective weed management in grass and cereal crops and are generally phytotoxic to broadleaf plants, causing little or no damage to monocots. Monocot crops are tolerant, in general, because of restricted translocation, enhanced metabolism, and the lack of a vascular cambium in their phloem tissue. Broadleaf species can be tolerant because they metabolize the herbicide to a less toxic form. These herbicides are considered mimics of the natural plant auxin and are thought to induce changes in gene expression which lead to plant death. The mechanism of auxinic-herbicide resistance as selected for in some weed species is yet unknown.
For more information on this topic, go to the advanced lesson on this Site: Auxinic Herbicide Mechanism(s) of Action - Part 2 - Advanced Lesson.