Difenzoquat
Difenzoquat is a selective, postemergent herbicide used to control wild oats in barley and wheat, and first registered in the US in 1975.
Difenzoquat is a phenylpyrazole and pyrazole herbicide, and a quaternary ammonium compound. It is absorbed via the foliage and acts by rapidly destroying cell membranes.
Usage
In the US, difenzoquat is applied once per season as a ground or aerial broadcast treatment; it is sold as a soluble concentrate or liquid, and 64 to 77% of difenzoquat sold is applied to wheat, as of 1994.It has also been marketed as "Finaven", "Yeh-Yan-Ku" and "Mataven".
Safety
Difenzoquat is a severe eye irritant, and has moderate acute toxicity on skin contact or via ingestion. Subchronic oral trials showed no effects on dogs, but rabbits in a dermal study developed skin reactions. In chronic trials, rats lost weight without other effect; dogs lost weight, suffered high mortality, developing tremors, lethargy and irregular gait.Difenzoquat appears to be non-carcinogenic. It is not mutagenic. The EPA estimates that humans are exposed to extremely low-level residues which pose no known risks. Its NOEL is 25 mg/kg/day.
Environmental behaviour
Difenzoquat is persistent and relatively immobile in soil, with little risk of groundwater contamination. Difenzoquat's persistence is slighty uncertain though, field trials indicate it dissipates much quicklier than believed.Difenzoquat is practically non-toxic to birds and freshwater fish, but moderately toxic to freshwater invertebrates. It is non-toxic to honey bees. Chronic ecological toxicity is thought to be unlikely.