Pyroxasulfone is a pre-emergence herbicide that works by inhibiting the production of very long-chain fatty acids (VLCFAs) in plants, preventing weed seedling emergence and early growth. Its structure is based on the existing herbicide thiobencarb, but Pyroxasulfone requires a lower dose (100–250 g/ha) and offers greater stability, resulting in longer-lasting weed control. It is widely used in corn, soybean, wheat, and other cereal crops for controlling grass and broadleaf weeds.
Parent: Pyroxasulfone
Impurities in Pyroxasulfone can arise due to chemical synthesis, degradation, or improper storage conditions. Regulatory authorities such as the EPA and EU pesticide regulatory agencies impose strict impurity limits to ensure environmental and human safety.
Process-Related Impurities
• Unreacted intermediates from chemical synthesis
• Residual solvents (e.g., methanol, ethanol, dichloromethane)
• By-products formed during the manufacturing process
Degradation Impurities
• Oxidation products due to exposure to light and oxygen
• Hydrolysis impurities from moisture exposure
• Thermal degradation products at high temperatures
Elemental Impurities
• Heavy metals from catalysts used in synthesis
• Trace levels of arsenic, cadmium, lead, and mercury
Analytical Techniques for Impurity Detection
• High-Performance Liquid Chromatography (HPLC)
• Gas Chromatography (GC)
• Mass Spectrometry (MS)
• Fourier-Transform Infrared Spectroscopy (FT-IR)
Pyroxasulfone is used as a pre-emergence herbicide to control annual grass and broadleaf weeds in:
• Corn
• Soybeans
• Wheat
• Other cereal and row crops
It is applied before or shortly after planting to prevent weed emergence.
Pyroxasulfone belongs to Herbicide Group 15, which includes very long-chain fatty acid (VLCFA) synthesis inhibitors. It works by disrupting lipid biosynthesis, preventing weed seedling development.
Pyroxasulfone is considered highly effective due to:
• Broad-spectrum weed control (both grasses and broadleaf weeds)
• Low application rate (100–250 g/ha)
• Long residual activity – provides season-long control in many cropping systems
• Excellent soil stability – remains active longer than many other pre-emergence herbicides
Zidua (a formulation containing Pyroxasulfone) controls:
• Grass weeds: Barnyardgrass, Crabgrass, Foxtail, Fall Panicum
• Broadleaf weeds: Palmer Amaranth, Waterhemp, Common Ragweed, Lambsquarters
