Penoxsulam, developed and produced by Dow AgroSciences LLC (Dow AgroSciences), is a trizolo pyrimidine herbicide applied in paddy fields with the widest herbicidal spectrum. It has great effect not only in aquatic weeds control but also in barnyard grass which has resistance to herbicides like quinclorac, propanil and sulfonylurea. With aquatic weeds’ higher resistance, penoxsulam plays a more vital part in weeds control.
Penoxsulam is a systemic herbicide that moves throughout the plant tissue and prevents plants from producing a necessary enzyme, acetolactate synthase (ALS), which is not found in animals. Susceptible plants will stop growing soon after treatment and become reddish at the tips of the plant. Plant death and decomposition will occur gradually over several weeks to months. Penoxsulam may be used to treat the invasive Eurasian watermilfoil (Myriophyllum spicatum). In other parts of the country, it is valuable as a rotational herbicide against the invasive plant hydrilla (Hydrilla verticillata). Desirable native species that may also be affected include sago pondweed (Stuckenia pectinata), Illinois pondweed (Potamogeton illinoensis), pickerelweed (Pontederia cordata), duckweeds (Lemna spp.) and arrowhead (Sagittaria spp.).
Penxosulam is a triazolopyrimidine sulfonamide herbicide, which is used to control the growth of annual grasses, sedges, and broadleaf weeds in rice agriculture. The compound inhibits the synthesis of acetolactate and targets the biosynthesis of branch-chained amino acids, a metabolic pathway found in plants, fungi, and microorganisms. Acetolactate synthase (ALS) inhibitors are present in most effective herbicides. They are used in agriculture because they show a broad weed control spectrum, crop selectivity, are safe to humans, and can be applied at relatively low usage rates.
In the mammalian metabolism studies, penoxsulam was rapidly and almost completely absorbed upon oral administration. There was no evidence of bioaccumulation. Excretion was rapid, but dose and sex dependent as excretion was primarily observed via faeces in males and primarily excreted in urine in females. Penoxsulam was bio-transformed to a large number of metabolites; however the majority of the radioactivity was eliminated as unchanged parent compound.
Penoxsulam can be quickly absorbed by the soil. Leachability is weak in most paddy soils. Its adsorption capacity in clay soil and soil with high organic matter is higher than that in light soil and soil with low organic matter content. In soil with pH>8.0, it has the risk of aggravating phytotoxicity. The agent is easy to migrate in the soil and does not stay long-term. Due to the low saturated vapor pressure of the agent, it is not easy to evaporate from the water; in the irrigated rice field, the chemicalbook half-life of the agent is 2-13d; photolysis and microbial degradation are the main disappearance ways of penoxsulam. It is resistant to hydrolysis in water, but it can quickly disappear after photolysis in shallow water. The photolysis of the aqueous solution is divided into three ways: sulfophthalamide bridge cleavage, the gradual degradation of trimethoprim and its substituents, and sulfophthaleyl photooxidation . This photolysis product can remain for a long time. In paddy soil, anaerobic microbial degradation is an important process for the disappearance of pesticides, and its disappearance speed is as fast as photolysis.
Penoxsulam is an acetolactate synthase inhibitor herbicide. It provides broad-spectrum control of many annual, biannual, and perennial weeds.
It is used mainly as a post-emergency foliar spray or a granular formulation for the control of broadleaf, sedge, and grass weeds in transplanted, dryseeded, and water-seeded rice. It is also effective against broadleaf weeds in corn, sorghum, wheat, barley and other cereal crops, lawns, golf courses, parks, cemeteries, athletic fields, sod farms, tree and vine crops, range and pasture, roadsides, and other crop and non-crop uses.
As penoxsulam does not bind strongly to either soil or sediments, it tends to be very mobile in both aqueous and terrestrial environments, which makes it a contaminant to groundwater. Penoxsulam is registered for use in Germany, France, Portugal and the USA.
[1] Patent: US 20140274711 A1 “Synergistic weed control from applications of penoxsulam and pethoxamid”
[2] http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/512.htm
[3] alyani Paranjape, Vasant Gowariker, V N Krishnamurthy, Sugha Gowariker, The Pesticide Encyclopedia (2014)
ChEBI: Penoxsulam is a member of triazolopyrimidines.
