Chapter 17: MOA Part 3: Growth Regulators (Auxinic Herbicides)
17.2 Importance of Auxin
The term “auxin” is from the Greek word, auxein, meaning ’to increase’ and was first used by Frits Went in 1926 to describe the natural plant hormone, indole-3-acetic acid (IAA), which is the compound that caused curvature of oat coleoptiles.
The following YouTube video describes IAA’s important role in plant growth, including how it causes plants to grow towards the sun and its effects on root growth.
Synthetic auxins are herbicide chemicals that look very similar to the plant’s IAA. There is one herbicide Mode of Action with two Sites of Action that negatively affect plants by mimicking an overdose of auxin. The second SOA class inhibits how plant auxin is moved into cells.
Growth Regulators
- Group 4. Synthetic Auxins (SA) (HRAC Group O)
- Group 19. Auxin Transport Inhibitors (ATI) (HRAC Group P)
Review and Reflection