Aminocyclopyrachlor

After the first introduction in 2010, aminocyclopyrachlor was registered as an active ingredient in Australia in September 2014, but no product containing it was registered until Bayer's "Method 240 SL" in 2022. Before this, aminocyclopyrachlor was registered in New Zealand. Method is a 240 g/L soluble concentrate (SL), with aminocyclopyrachlor present as its potassium salt. although they voluntarily withdrew the registration in 2014. It may be applied at 312 g/Ha (active ingredient) in 100-400 L/Ha of water. ==Mechanism of action==

Aminocyclopyrachlor is a systemic herbicide and acts by disrupting gene expression. It belongs to the pyrimidine carboxylic acid chemical family and mimics auxin which is a growth-regulating hormone in dicots including broadleaf terrestrial plants. This causes undifferentiated cell division and elongation, with resulting appearance characteristic of auxin herbicide damage such as leaf twisting and curling. This makes it a Group I (Australia), or equivalently Group O (Global) or Group 4 (numeric) herbicide, under the HRAC classification system. Chemical properties It has some solubility in water, 2.81 g/L, more so in methanol, 36.7 g/L, and is practically insoluble in acetone, 0.96 g/L, dichloromethane, 0.2 g/L, acetonitrile, 0.65 g/L and n-octanol, 1.9 g/L. The low vapor pressure and Henry's law constant suggest that it will not disperse through the air. A low octanol/water partition constant of -1.12 (Log Pow) indicates it be not bioaccumulative, and technical grade aminocyclopyrachor should be stable for at least 2 years in normal storage conditions. Aminocyclopyrachlor is not flammable, explosive or auto-flammable and except for photo-degradation, the pure aminocyclopyrachlor isn't chemically incompatible with oxidising or reducing agents and is essentially non-hazardous. ==Ecotoxicity==

Although auxin-mimicking herbicides are selectively toxic to dicots, some angiosperms are also affected. Due to the emergence of damage to some conifer species, the United States Environmental Protection Agency and DuPont advised professional applicators and residential consumers to not use Imprelis where Norway spruce or white pine trees are present on or near the property being treated. ==Residue==

Tomato plants are the preeminent bioassay platform for testing auxin herbicide damage because they are extremely sensitive to it. In a controlled greenhouse test, tomato plants were mulched with the remains of Norway spruce and honey locust trees that were damaged from exposure to AMCP that had been applied to adjacent turf grass more than a year prior to the tomato tests. The mulch (i.e. shredded foliage and stems) contained 4.7 to 276 ppb of AMCP. All of the AMCP-exposed tomato plants sustained visible damage while the unexposed controls showed no damage. Residual AMCP in the exposed tomato plants ranged from 0.5 to 8.0 ppb. The human ADI is 2.8 mg/kg/day, (224 mg/day for an 80 kg adult) based on a NOEL of 297 mg/kg/d in a 2 year long study on rats. ==Environmental behavior==

As with aminopyralid, AMCP-contaminated soil, mulch, or compost should be excluded from sensitive crops or gardens. The dissipation half-life (DT50) time of AMCP has been measured at between 3 and >112 days in four soils from the Northern Great Plains. More recently, the time required for 90% degradation (DT90) was found to be 622 to 921 days, although an APVMA report cites a half-life in normal air of 42 hours, implying a wildly shorter DT90. As a practical matter, all material in AMCP-treated areas should be regarded as permanently poisonous to tomatoes and other nightshades until proven safe. ==Tradenames==

Aminoicyclopyrachlor has been sold as "DPX-KJM44", "Method", "Perspective", "Streamline", "Invora", "Viewpoint", "Plainview", "Navius", "TruVist" and "TruRange". This list may be incomplete. == References ==