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Azimsulfuron entered the crop protection scene in the late 20th century, developed by scientists who saw the need for selective control in flooded rice paddies. Early weed management in paddies relied heavily on older chemicals with broad toxicity, often damaging rice along with the weeds. Researchers experimented with new sulfonylurea structures, and through dogged effort at fine-tuning molecular arrangements, azimsulfuron was born. This compound hit the market in Asian rice-producing regions, giving farmers a chance to control sedges and broadleaf weeds without wiping out their main crop. Having grown up in a rural setting, I watched as these innovations gave farmers breathing room – higher yields, less weed pull labor – but pushed them to keep up with resistance concerns that soon followed.
Azimsulfuron stands as a post-emergence herbicide. The compound disrupts essential amino acid synthesis in target plants, putting the brakes on shoot and root growth. Marketed under names like Riguron and Milagro, the product comes in water-dispersible granule and wettable powder forms, typically at an 80% active ingredient concentration. It frees rice farmers from the endless grind of hand weeding and enables planting schedules to run on time, which, for smallholder farmers, means their livelihoods more secure and their kids in school instead of the fields.
Azimsulfuron appears as an off-white to pale yellow solid, with a melting point around 172–174°C. Its molecular formula reads C13H16FN7O5S2, and the molecule behaves as a moderately water-soluble compound, about 66 mg/L at room temperature. Its stability at a wide pH range means it works in both acidic and slightly alkaline environments—a handy advantage in variable paddy soils. This broad adaptability explains why field adoption became so widespread despite changing water chemistry or climate conditions across Asia’s rice belts.
Product labels set the application rate between 30–40 grams of active ingredient per hectare, and they stress low drift as critical during application. The product label carries firm warnings concerning aquatic toxicity, a nod to its design for flooded fields. Every packet includes instructions focused on timing – applications only post-emergence and strictly outside the booting stage in rice. Labels require the use of personal protective equipment (PPE): gloves, masks, and long sleeves. For me, seeing neighbors forego chemical safety for convenience emphasizes why these requirements matter; accidental spills and inhalation events aren’t stories, they’re reality on small farms.
Azimsulfuron synthesis follows a structured multi-step route, beginning with the coupling of a sulfonylurea core with a fluorophenyl group. Chemical engineers use precursors like 4,6-dimethoxypyrimidin-2-ylamine and ethyl 2,6-diethoxybenzoate, following up with sulfonation and coupling with a diazotized aromatic amine. Each stage asks for precise temperature control and scrubbed reaction vessels, since impurities directly affect field performance and persistency. Chemists running these syntheses know solvent purity can mean the difference between stable product and batch recalls that ripple all the way down to planting.
The key reaction centers on sulfonylation of the pyrimidine ring, bolstered by the introduction of a triazole moiety that fine-tunes selectivity. Modifications to the molecule’s phenyl and pyrimidine rings have led to analogues with altered weed spectra or faster breakdown rates in soil. Research teams actively tweak substituents to fend off resistance, hoping to stay a step ahead of mutating weeds. Having seen resistance flush through fields after a few seasons, I appreciate the ongoing chase—scientists in labs trying to outthink nature while growers wrestle with day-to-day weed pressure.
Azimsulfuron carries multiple product identities depending on where it lands commercially. In Japan, it often sells as Riguron; in Europe and Latin America, Milagro or various house brands step in. Regulatory paperwork refers to it as 1-(4,6-dimethoxypyrimidin-2-yl)-3-[(4,6-dimethoxypyrimidin-2-yl)aminocarbonyl]-1H-sulfonylurea, but few outside industry circles memorize the mouthful. The proliferation of synonyms sometimes muddies cross-border trade, drawing occasional headaches for exporters who suddenly need translation to satisfy customs or regulators.
Safety protocols demand chemical-resistant gloves, eyeshields, and full-length clothing during mixing or spraying. Labels outline restricted-entry intervals of at least 24 hours, with stricter controls during periods of heavy rainfall or field flooding. Chronic exposure can irritate skin or eyes, while inhalation risks grow when sprayers ignore masks. I’ve witnessed friends shrug at mask warnings, and later wash out their eyes at the pump shack—real consequences. Local extension agents spend hours drilling safety routines, knowing that a slip in PPE can mean lost working days or worse. Return lines for empty packaging, required in several countries, reflect a growing awareness that rural waste disposal shapes entire community health outlooks.
Azimsulfuron now serves millions of hectares in Asia and beyond, targeting barnyard grass, sedges, and a variety of broadleaf rice weeds. Its strengths shine in rain-fed and irrigated paddies, but new research highlights its extension to wheat and sugarcane rotations under experimental permits. This herbicide’s precision means less soil disruption, as workers steer clear of tilling and bank on the chemical’s selectivity for weed control. In regions moving toward mechanized transplanting, the product syncs with aerobic rice models, closing labor gaps when hand weeding falls short.
Ongoing R&D centers on broadening weed control spectra, tweaking breakdown rates, and engineering pre-mixes that pair azimsulfuron with complementary actives. Teams evaluate soil dissipation curves, looking for residues that vanish before harvest. Universities monitor environmental runoff and resistance gene clusters, building data for future registration battles. In my network, people rely on university bulletins to guide spray routines—laboratory and field researchers play a front-line role in translating science into practice under local agronomic conditions.
Acute toxicity remains relatively low for mammals, with LD50 values above 5000 mg/kg in rat studies, but aquatic species like daphnia or freshwater fish show heightened sensitivity. Prolonged exposure to sub-lethal doses changes soil microflora, which matters to farmers pushing sustainable field rotations. Carcinogenicity tests so far return negative, but regulatory agencies insist on regular re-evaluation, especially as chronic low-dose exposures accumulate in rice-fish farming systems. I’ve met aquaculture families who juggle their livelihood between rice and fish—their skepticism towards herbicide use always sounds louder after a fish die-off, regardless what safety data sheets claim.
Azimsulfuron’s future hinges on stewardship, regulatory scrutiny, and the herbicide-resistance arms race. New chemistries tempt with next-generation weed control, but few match the cost and reliability of azimsulfuron when managed responsibly. Research on enzyme-resistant weed biotypes urges a shift toward integrated weed management: rotating herbicides, introducing cover crops, and leveraging precision application technology. Farmers who’ve seen resistant barnyard grass swallow up fields now experiment with chemical rotations, biological control agents, and smarter water management. Governments push for safer disposal, community training programs, and real transparency on residue risks. Ultimately, the compound’s legacy will rest not just on yield numbers but on how it shapes, and adapts to, a world where food, health, and environmental expectations grow sharper each season.
Walk through a paddy field during weed season and you’ll understand the everyday struggle of rice growers. Weeds compete for water and soil nutrients, cutting yields and making life harder for people working the land. In most rice-producing countries, pressure to maximize the harvest keeps farmers searching for better ways to manage weeds. That’s where azimsulfuron enters the story.
Azimsulfuron is a selective herbicide, designed with rice paddies in mind. I first came across it as a recommendation from agronomists in Southeast Asia, who said it was helping keep broadleaf weeds and sedges at bay without harming rice plants. That’s not a minor advantage. Fields treated with azimsulfuron showed clearer rows and more vigorous rice growth, since the crop wasn’t sharing resources with unwelcome neighbors.
People in agriculture value results, and azimsulfuron delivers — especially on tough weeds like monochoria and sedges that often slip by other products. It acts by disrupting a certain enzyme in nuisance plants, which stunts their growth and gives the rice crop an edge. This enzyme, called acetolactate synthase, doesn’t play the same role in rice at application rates typically used, so harm stays focused on the target plants.
Easy as it is to celebrate weed-free rows, any talk about agrochemicals raises important questions. Is it safe? How does it impact people and the environment? Here, personal experience matches up with published research: azimsulfuron breaks down relatively quickly in wet field conditions and doesn’t accumulate in soil or water. Regulatory agencies, including those in Japan and Europe, review safety data before greenlighting its use. Field workers, including friends and family, always take proper precautions — gloves, masks, careful handling — to reduce risks.
Reports of resistant weeds have surfaced, though. As more growers rely on the same product year after year, some weeds may develop ways to survive. That means azimsulfuron can’t become the only line of defense. Rotating herbicides, combining chemical and manual weeding, and exploring natural cover crops keeps resistance in check. The lesson sticks: no silver bullet exists in weed management.
Feeding a growing population depends on reliable harvests, and that reality keeps rice farmers innovating. The real measure of azimsulfuron’s value isn’t just how clean a field looks but how its use fits into bigger sustainability goals. Responsible use, careful planning, and respect for local soil and water balance mark the difference between short-term gain and true stewardship.
Azimsulfuron shows up as part of a wider toolkit. It helps save labor, boosts yields, and takes a load off small producers who compete in a tough global market. Rice makes up a staple food for millions. Ensuring healthy, profitable fields in a way that looks after the environment is a job that demands good science, sound judgment, and a willingness to adapt.
As farmers, agronomists, and researchers keep trading notes and refining methods, the shape of modern agriculture keeps shifting. Azimsulfuron finds its place not as the hero but as one piece among many. The smartest users stay informed, switch up their strategies, and always look for ways to grow food safely and responsibly.
Azimsulfuron pops up on many farms that rely on rice. Farmers look at flooded fields and hope for a new season, but one thing never changes: weeds. They choke out young rice, eating up nutrients and light. Azimsulfuron steps in right at this messy spot. Developed in the 1990s, agrochemical experts needed a way to knock out tough sedges and broadleaf weeds that outsmarted older chemicals. This compound came out of Japanese labs to offer a shot at better yields in muddy fields.
At the heart of its action lies enzyme blocking. Azimsulfuron jams a key process for weed growth. Biologists call this process acetolactate synthase, or ALS for short. Plants build amino acids using this enzyme. Cut off the supply, you cut off growth. Weeds meet Azimsulfuron, their internal machinery grinds down, and soon they yellow, wilt, and disappear under the waterline. Unlike many broad-spectrum herbicides, it targets weeds close to the soil—leaving rice able to keep growing.
Folks on the ground see the difference. I have talked with farmers in Southeast Asia who say it turns a carpet of sedges into clean rows within a week. They spray at low rates—just a few grams per hectare, not buckets—and knock back stubborn weeds that shrugged at old-school treatments. This focus matters for their wallets. By clearing weeds early, they don’t gamble away a season or waste seed and fertilizer. Researchers recording field trials see up to 90% weed reduction in test plots, especially against tough Cyperus and Monochoria species.
No one gets a free ride, though. Nature pushes back against every shortcut. Azimsulfuron only hits weeds that haven’t learned to work around ALS blocking. Overusing it gives weeds a blueprint for survival. Several studies in Asia and Europe now show populations of barnyardgrass and smallflower umbrella sedge that pop right back up after treatment. It rings the bell for rotating chemistry—something extension officers, agronomists, and local co-ops hammer into their training days. Mixed strategies, like alternating herbicides and crop rotations, close the loopholes that rogue weeds use to stage a comeback.
Food safety and the environment always matter. Azimsulfuron breaks down fairly fast in most soils. Crops like rice don’t take up much of it, so residue levels in food stay low. Regulatory reviews in the EU and Japan put it on the list of approved rice herbicides, as regular monitoring checks residue limits and runoff risk. Still, standing water and rice paddies mean extra vigilance—runoff from poorly managed spraying may drift into streams, causing regulators to insist on buffer zones and careful dose timing.
I see hope in farmer networks and tech adoption. Digital platforms now send up alerts about weed resistance in local languages. Seasoned growers swap tips, mixing planting dates, crop types, and smart herbicide scheduling to stretch out every tool’s lifespan. That’s how they find a balance: Azimsulfuron as one tool in a bigger kit. It helps feed families and cities, and with watchful use it stays useful for the long haul.
Azimsulfuron serves as a popular herbicide for rice growers, especially in Asia and some parts of Europe. Its main job involves helping paddy fields stay free of broadleaf weeds, sedges, and some annual grasses. This selective herbicide performs best when used in direct-seeded and transplanted rice, as it attacks weeds that threaten young rice plants without hurting the crop itself.
Farmers living through weed-choked fields every season understand how quickly unwanted plants can sap water, nutrients, and the hope of a decent yield. I remember walking through a friend’s rice plot after a hard rain—sedges everywhere, crowding out the neat lines of freshly planted rice. The difference after an azimsulfuron application, done according to label directions, marked the field. Healthy rice lined up strong. The weeds lost ground fast. This herbicide fits into growers’ practical weed control strategies and has become trusted across wetland rice systems. Research from the International Rice Research Institute highlights that integrated weed management—including azimsulfuron—raises rice yields by as much as 30% over fields left untreated.
Azimsulfuron does not work on every crop. On the positive side, its selectivity gives confidence to rice growers looking for ways to manage mixed weed problems. Safe use rests on targeting its application to registered crops and approved plant growth stages. Applying to off-label crops or under off-label conditions risks crop injury and doesn’t provide any more help to yield or weed suppression. In vegetables, maize, or wheat, for example, this herbicide causes too much harm and brings regulatory penalties on top of an already stressed farm budget.
Some countries allow minor use in sugarcane or certain specialty crops, but the risk of drift or leftover residue often outweighs any small benefit. Scientists keep looking for safe use in more crops, but rice remains the headline here. Responsible stewardship matters. If azimsulfuron gets misused or overapplied, resistant weed populations can quickly take over. Asian rice regions have reported more than a dozen resistant sedge and broadleaf weed species due to repeated overuse. Managing herbicide resistance means switching up chemistry, hand-pulling survivors, rotating rice with other crops, and using good water management. These approaches help keep both effectiveness and value for the next set of seasons.
Chemical use draws attention for safety and environmental impact, and that includes azimsulfuron. Approved use means checking water tables and keeping buffer zones. This matters in the rural communities near paddy fields, whose health depends on clean water. The European Food Safety Authority and US Environmental Protection Agency evaluate such herbicides for groundwater safety and food residue, setting limits based on toxicity and exposure risks. Monitoring compliance is not just box-ticking—it keeps land healthy for future generations and provides the transparency that consumers demand.
Azimsulfuron brings benefits, but always use it in line with up-to-date local advice, crop safety data, and stewardship schemes. Each step strengthens trust between farmers, consumers, and the wider food system. In the end, it’s a tool—one of many—that farmers need for growing rice in a demanding world.
Some herbicides come with confusion built right into the label. Azimsulfuron lands in that camp, often raising questions about the “right” way to use it. Out in the fields, I’ve seen both bumper crops and disaster patches, sometimes just down to choosing a rate that matched the real problem. The stakes matter—wrong dosage can scorch your rice or leave the weeds untouched.
Azimsulfuron acts as a sulfonylurea herbicide, mainly targeting broadleaf weeds and sedges in rice paddies. Recommended application rates typically fall between 20 to 40 grams of active ingredient per hectare. If you get too heavy-handed and move beyond 40 grams, you risk causing crop injury, especially if field drainage isn’t quick. Underapplication, on the other hand, wastes time and money—weed survivors prove tougher next round.
Agriculture extension bulletins from places like Japan, Vietnam, and parts of India have landed on similar rates for transplanted and direct-seeded rice. They keep it in that 20–30 gram sweet spot for clear control without running up costs or resistance. In studies shared by the International Rice Research Institute, plots treated in that window showed solid weed suppression and low re-sprout, with minimal impact on crop health.
It’s easy to look at herbicides as a set-it-and-forget-it tool. My experience walking muddy paddies says otherwise. Precision spells the difference between a clean harvest and a long, painful lesson in re-growth. Paying attention to field conditions, weed spectrum, and timing can save a whole season’s work.
Dosing lower than the active threshold results in patchy control and primes the field for resistance. Sulfonylurea-resistant barnyard grass, for example, now troubles more growers across Asia. This isn’t just a worry among academics—watching labor costs and yield losses climb because of stubborn sedges changes opinions quickly.
Sticking to label rates doesn’t just help with weed management. Going overboard with chemicals leaches into the water, hitting both soil biology and fish populations downstream. Several farm neighbors have moved toward tighter dose tracking, using calibrated sprayers and keeping better records—not for paperwork, but because their own yields improved.
Azimsulfuron’s persistence in the environment ranks lower than some older chemistries, but skipping the buffer zone near irrigation channels or using the wrong nozzle wide open can undo that advantage fast. Decisions made while tired or under time pressure stick with a field for years.
Stubborn weeds tempt you to reach for a heavy hand, but long-term success calls for rotation and integrated practices. Rotating herbicides and working in mechanical weeding or alternate wetting and drying sets up the next crop with fewer problems. Local extension agents and farmer networks share real stories of both mishaps and wins—listening to them often proves more useful than a glossy pamphlet. If there’s any lesson that sticks, it’s that careful, informed dosing beats guesswork every single time.
Respected agronomists, research groups, and years of boots-on-the-ground experience all point in the same direction: 20–40 grams per hectare for Azimsulfuron, matched to the crop growth stage and field realities. Fine-tuning pays off both for your pocket and the patch of land you call your own.
Years spent working with farmers bring some clarity. Anyone who spends summer days knee-deep in muddy paddy fields knows how tough rice weeds can get. Azimsulfuron appeared on the scene as a selective herbicide, helping rice growers keep weeds at bay without killing their livelihood. Most users wear gloves and masks, not taking chances, but questions about what drifts beyond the field edge come up at every season’s turn.
Azimsulfuron fights weeds by blocking an enzyme in their growing process. That stops weeds in their tracks, but anything that changes plant life has ripple effects. Rice fields often overflow, so run-off matters. Studies in Europe and Asia tracked azimsulfuron in water and found much of it breaks down with sunlight or soil bacteria. Some sticks around for a few weeks, though, especially if the soil stays wet and cold. This slow breakup brings risks of nearby streams catching trace amounts.
Fish and birds live close to fields. Standard tests on carp and ducks show azimsulfuron at recommended doses gives little trouble in direct contact. Amphibians, insects, and aquatic plants are another story—some react even to low doses. Certain algae and plankton, forming the bottom of the food chain, show signs of stress. A rice field drains, snails and frogs take a hit, and that change can climb up to birds and bigger fish if used year after year.
People handling herbicides every day always face some risk. With azimsulfuron, most toxicology reports suggest low acute toxicity for humans. The skin takes little up. Swallowing brings more risk; on rare occasions, stomach trouble or dizziness. Chronic exposure sits harder to assess. A few studies watch for lasting health effects—cancer, hormonal imbalances, nerve problems—and find no consistent signs of trouble at legal doses, but years of farm work add up in ways big studies sometimes miss.
Europe approved azimsulfuron after long debate but set tight rules about how and where to use it. Buffer zones around water help. In Japan, strict timing rules apply to prevent drift before heavy rain. Each country sits with its own rain cycles, wildlife, and food safety rules, yet no place treats such substances lightly anymore. Everybody watches for resistant weeds or traces found in rice exports—one slip brings big consequences for rural incomes and public health alike.
Integrated weed management, using several tactics instead of relying on a single herbicide, points to a safer future. Spraying only when needed, using GPS-guided tools to reduce waste, and rotating with non-chemical options shrink both environmental load and health worries. Research keeps offering new rice strains that crowd out weeds themselves. Adding buffer plants or constructed wetlands to catch runoff before it hits rivers helps both wildlife and communities downstream. In the end, regular monitoring, honest data, and a willingness to switch up the playbook matter more than promises on a label.
| Names | |
| Preferred IUPAC name | 1-(4,6-dimethoxypyrimidin-2-yl)-3-(methylsulfonyl)-1H-1,2,5-oxadiazol-4-yl)urea |
| Other names |
Valor AZ 518 MSI 518 Nihon Nohyaku AZ 518 |
| Pronunciation | /əˌzɪmˈsʌl.fjər.ɒn/ |
| Identifiers | |
| CAS Number | 120162-55-2 |
| 3D model (JSmol) | `3D model (JSmol)` string for **Azimsulfuron**: `CN1C(=O)SC(n2nc(cc2N)N(S(=O)(=O)C)C)=N1` |
| Beilstein Reference | 3581593 |
| ChEBI | CHEBI:76356 |
| ChEMBL | CHEMBL24836 |
| ChemSpider | 20223 |
| DrugBank | DB11360 |
| ECHA InfoCard | ECHA InfoCard: 100000021689 |
| EC Number | EC 603-701-7 |
| Gmelin Reference | 112024 |
| KEGG | C18312 |
| MeSH | D000077342 |
| PubChem CID | 86130 |
| RTECS number | AG8488000 |
| UNII | M46M1412Y6 |
| UN number | UN3077 |
| Properties | |
| Chemical formula | C13H16N8O5S |
| Molar mass | 410.14 g/mol |
| Appearance | White crystalline solid |
| Odor | Odorless |
| Density | 0.44 g/cm³ |
| Solubility in water | 3.39 mg/L (20 °C) |
| log P | 1.59 |
| Vapor pressure | 1.9 × 10⁻⁷ mPa (25 °C) |
| Acidity (pKa) | 5.0 |
| Basicity (pKb) | 3.36 |
| Magnetic susceptibility (χ) | -7.7e-10 |
| Dipole moment | 3.77 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 489.5 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -611 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -809.6 kJ/mol |
| Pharmacology | |
| ATC code | QJPE |
| Hazards | |
| Main hazards | May cause damage to aquatic organisms and plants; avoid release to the environment. |
| GHS labelling | GHS07, GHS09 |
| Pictograms | GHS07,GHS09 |
| Signal word | Warning |
| Hazard statements | H410: Very toxic to aquatic life with long lasting effects. |
| Precautionary statements | P280 Wear protective gloves/protective clothing/eye protection/face protection. P273 Avoid release to the environment. P391 Collect spillage. P501 Dispose of contents/container in accordance with local/regional/national/international regulations. |
| Autoignition temperature | “470 °C” |
| Explosive limits | Explosive limits: Not explosive |
| Lethal dose or concentration | LD₅₀ (oral, rat): > 5,000 mg/kg |
| LD50 (median dose) | LD50 (median dose): >5000 mg/kg (rat, oral) |
| NIOSH | No NIOSH assigned. |
| PEL (Permissible) | 0.1 mg/m³ |
| REL (Recommended) | 35 g a.i./ha |
| Related compounds | |
| Related compounds |
Bensulfuron-methyl Ethoxysulfuron Imazosulfuron Pyrazosulfuron-ethyl |
