Benefits of BHA technology
- Herbicide is easy to deliver through a hand-held applicator injecting a capsule containing herbicide directly into tree stem or trunk
- There is no chemical exposure to the person delivering the herbicide – safe to use
- Encapsulated herbicides can be delivered all year round – especially useful to treat trees in down-time
- No chemical drift or leakage into the environment
- It is a systemic and persistent herbicide with non-selective activity.
- In soil, imazapyr is degraded primarily by microbial action.
- It is resistant to photolysis or general chemical activity in soil and has a half-life of several months.
- It is readily ionised at soil pH greater than 5 and does not readily adsorb to soil particles.
- In aqueous environments however it is quickly decomposed in days.
- It was granted USA EPA approval for use in aquatic environments in 2003.
- It is also considered relatively slow acting presumably due to the necessity of depleting stores of amino acids.
- It is not easily degraded within plants so is considered a good contender for killing large woody species.
How does Imazapyr work?
- Imazapyr belongs to the imidazolinone family of herbicides that act by inhibiting acetolactate synthase (ALS) (Herbicide Group B), the first enzyme in the catalysis of the branch-chain amino acids valine, leucine and isoleucine necessary for protein production and cell growth.
- After application into the stem, imazapyr is distributed by the plant’s water (xylem) and nutrient transportation (phloem) systems into the leaves and roots.
- It can remain active in the plant until the plant dies and microbial activity destroys the herbicide.
- However, there is some evidence that some legume species (eg mesquite) may exude the chemical through the roots as a defence mechanism.