What Is Metsulfuron-methyl and Why It’s Widely Used in Agriculture

What Is Metsulfuron-methyl and Why It’s Widely Used in Agriculture

Metsulfuron-methyl is a highly effective sulfonylurea herbicide known for its broad-spectrum control of broadleaf weeds and some grasses. Used at ultra-low doses—typically measured in grams per hectare—it offers farmers a cost-effective and environmentally conscious solution for selective weed control. As a systemic, post-emergence herbicide, it moves through the plant’s vascular system to stop weed growth at its roots, literally.

One of the key advantages of metsulfuron-methyl lies in its exceptional crop selectivity. It can be safely applied in major cereal crops like wheat, rice, and maize, without damaging the crop itself. At the same time, it provides reliable suppression of numerous hard-to-kill annual and perennial broadleaf weeds, making it a preferred tool in both conventional and conservation agriculture systems.

Additionally, metsulfuron-methyl is low in toxicity to humans and animals, readily biodegradable, and compatible with integrated weed management strategies. These attributes make it a popular choice not only for farmers but also for agrochemical distributors, formulation developers, and registration consultants who seek efficient, sustainable herbicide solutions.

In the following sections, we’ll explore how metsulfuron-methyl works, where it’s most commonly used, and why it continues to play a central role in modern weed control strategies.

How Metsulfuron-methyl Works: Mode of Action and Weed Control Behavior

Metsulfuron-methyl belongs to the ALS (acetolactate synthase) inhibitor class of herbicides, also known as Group B in the HRAC classification. Its mode of action is based on inhibiting the synthesis of essential branched-chain amino acids—specifically valine, leucine, and isoleucine—within the target plant. By blocking the ALS enzyme, metsulfuron-methyl effectively halts cell division and growth, causing susceptible weeds to stop developing shortly after treatment.

This systemic herbicide is absorbed through both foliage and roots, then translocated throughout the plant’s vascular system. Once inside, it accumulates in the growing points, which leads to rapid cessation of shoot and root elongation, followed by leaf chlorosis and eventual plant death over the course of several days to weeks—depending on species, size, and weather conditions.

Importantly, metsulfuron-methyl acts selectively, targeting broadleaf weeds while being well-tolerated by cereals like wheat and rice. Its low application rates (as low as 4–6g/ha) make it a potent tool in integrated weed management programs, especially where resistance management and environmental safety are top priorities.

Where Metsulfuron-methyl Excels: Crops, Land Types, and Target Weeds

Metsulfuron-methyl is widely used in both agricultural crop production and non-crop land management due to its strong control of a broad range of annual and perennial broadleaf weeds. Its selectivity and persistence make it a valuable tool for farmers, land managers, and agrochemical programs across varied geographies.

Agricultural Use in Major Crops

Metsulfuron-methyl is registered and effectively applied in:

• Wheat fields: For early-season post-emergence control of broadleaf weeds.

• Rice paddies: Especially in dry direct-seeded rice, where it helps suppress early weed competition.

• Corn fields: Typically as part of a mixture for improved spectrum, targeting early broadleaf intruders.

• Barley and oats: Used in similar fashion to wheat, offering early-season weed protection.

Non-Crop Applications

In addition to row crops, metsulfuron-methyl is widely applied for:

• Pasture and rangeland maintenance

• Forestry sites

• Utility rights-of-way

• Roadsides and railway embankments
  These non-crop uses benefit from metsulfuron-methyl’s long residual control, low dose rates, and compatibility with minimal-tillage programs.

Weeds Effectively Controlled

Key susceptible species include:

• Chenopodium album (lamb’s quarters)

• Polygonum spp. (knotweed)

• Amaranthus spp. (pigweed)

• Capsella bursa-pastoris (shepherd’s purse)

• Galium aparine (cleavers)

• Stellaria media (common chickweed)

• Veronica spp. (speedwell)

• Geranium spp. (cranesbill)
  These are among the most troublesome weeds in cereals and pasture systems, and metsulfuron-methyl’s systemic action ensures both suppression and prevention of regrowth.

Recommended Use Rates of Metsulfuron-methyl Across Crops

One of the standout features of metsulfuron-methyl is its extraordinary efficacy at extremely low doses. This allows for efficient weed control with minimal chemical input, reducing environmental load and application costs. However, effective and safe use depends on crop type, application timing, and regional conditions.

1. Wheat and Barley

• Use Rate: 4–6 grams active ingredient per hectare (g ai/ha)

• Application Timing: Post-emergence when the crop is at the 2–5 leaf stage and target weeds are at the 2–4 leaf stage.

• Notes: Commonly tank-mixed with 2,4-D or Dicamba to broaden the weed control spectrum. Safe for most wheat varieties, but always check varietal tolerance.

2. Dry-Seeded Rice (DSR)

• Use Rate: 5–7 g ai/ha

• Application Timing: Pre- or early post-emergence stage of weeds.

• Notes: Ideal for controlling early-season broadleaf weeds and sedges in rice fields, especially when water management is limited.

3. Corn (Maize)

• Use Rate: 4–6 g ai/ha, often as part of a combination herbicide

• Application Timing: Post-emergence, when corn is at the 3–5 leaf stage.

• Notes: Alone, metsulfuron-methyl has limited grass control in corn; it is typically mixed with nicosulfuron or atrazine for broader-spectrum activity.

4. Pasture and Rangeland

• Use Rate: 10–15 g ai/ha (depending on weed pressure and species)

• Application Timing: When target weeds are actively growing, usually spring or early summer.

• Notes: Offers residual control with minimal regrowth. Not to be applied in recently reseeded pasture areas.

5. Non-Crop Land

• Use Rate: Up to 20 g ai/ha for persistent perennial weeds

• Application Timing: Flexible—can be applied throughout the year depending on vegetation cycle.

• Notes: Used in railways, roadways, utility rights-of-way, and forestry sites for long-term vegetation management.

Proper calibration of sprayers and adherence to label instructions is essential to prevent over-application or crop injury. Always consider local regulatory limits and varietal sensitivity before use.

Tank Mix Flexibility and Role in Integrated Weed Management (IPM)

Metsulfuron-methyl is widely valued not just for its solo efficacy but also for its excellent compatibility with other herbicides, making it a strategic component in tank mix programs and resistance management plans. Its chemical stability and low use rate allow it to be easily combined with both selective and non-selective herbicides without compromising performance or crop safety.

Common Tank Mix Partners

To broaden the spectrum of weed control, metsulfuron-methyl is frequently mixed with:

• 2,4-D or Dicamba: Enhances activity on tough broadleaf species, especially in wheat and barley.

• Glyphosate: For non-selective burndown in pre-plant or fallow applications.

• Atrazine or Nicosulfuron: In corn, to add grass and sedge control.

• Chlorimuron-ethyl or Halosulfuron: In soybean or rice for broader residual effects.

These combinations allow for a multi-site mode of action, reducing the risk of resistance buildup and supporting long-term sustainability in weed control programs.

Integrated Weed Management (IPM) Compatibility

Metsulfuron-methyl fits well into modern IPM programs due to:

• Low resistance risk when rotated or tank-mixed with other MOA groups.

• Minimal environmental footprint, supporting eco-friendly production goals.

• Extended residual control, reducing the frequency of re-application.

• Precision targeting, especially in conservation tillage or minimum-till systems.

Because it requires only grams per hectare, metsulfuron-methyl also supports low-input strategies favored in sustainable and regenerative agriculture.

Environmental Profile and Rainfastness of Metsulfuron-methyl

Metsulfuron-methyl is widely recognized for its environmental compatibility, making it a preferred choice in regions emphasizing sustainable agriculture and eco-conscious farming practices. Despite its potent biological activity, it demonstrates a favorable toxicological and environmental safety profile when used according to label directions.

Soil and Environmental Behavior

• Low application rates (typically under 10 g/ha) reduce the total active load entering the environment.

• Readily biodegradable under aerobic soil conditions, with microbial activity playing a key role in degradation.

• Minimal leaching potential, particularly in soils with high organic matter or clay content.

• Low volatility, reducing off-target drift and risk to nearby vegetation.

The herbicide is classified as practically non-toxic to birds, fish, bees, and most beneficial insects, which makes it suitable for use in integrated pest and habitat management zones.

Rainfastness and Weather Stability

• Metsulfuron-methyl typically becomes rainfast within 4 to 6 hours of application, depending on temperature and humidity.

• After absorption by foliage, the systemic action is unaffected by rainfall, allowing consistent performance even in regions with unpredictable weather patterns.

• In pre-emergence use, incorporation via rainfall or light irrigation may even enhance activity by aiding soil uptake.

Nevertheless, to maximize control and limit environmental movement, buffer zones near water bodies and label-specific pre-harvest intervals (PHIs) must always be observed.

Beyond Croplands: Metsulfuron-methyl for Pasture, Forestry, and Industrial Weed Management

While metsulfuron-methyl is best known for its role in cereal and rice fields, its versatility extends far beyond agricultural cropland. Thanks to its selective action and long residual activity, it has become a go-to solution for vegetation control in non-crop settings, especially in areas where low maintenance and long-term weed suppression are critical.

1. Pasture and Rangeland Weed Control

• Commonly used to suppress invasive broadleaf weeds such as thistles, knapweeds, ragwort, and dandelion, which compete with forage grasses.

• Helps restore desirable native grasses and improve pasture productivity without the need for frequent mowing or re-seeding.

• Typical use rates range from 10–20 g/ha, depending on weed species and density.

• Safe for established grass species like fescue, brome, and timothy, allowing for minimal disruption to grazing schedules.

2. Forestry and Tree Plantations

• Used in pre-plant or post-plant brush control in pine and eucalyptus plantations.

• Controls competing understory vegetation such as brambles, maple saplings, and wild legumes, enhancing early tree growth.

• Often mixed with other forestry herbicides for broader-spectrum action.

3. Roadsides, Railways, Utility Corridors

• Ideal for long-term vegetation suppression in hard-to-maintain areas like railway embankments, power line clearings, and highway shoulders.

• Effective in low-volume backpack or boom-sprayer programs, requiring minimal annual application.

• Helps reduce fire risk by managing dry broadleaf cover and invasive brush.

In all non-crop uses, metsulfuron-methyl provides cost-effective, low-labor weed control, while maintaining safety standards for applicators, livestock, and surrounding ecosystems. However, re-entry intervals and grazing restrictions should be carefully followed based on product label and regional regulations.

Global Market Adoption and Regional Use Cases of Metsulfuron-methyl

Metsulfuron-methyl has achieved widespread adoption in agricultural and non-agricultural sectors across more than 50 countries, reflecting its broad-spectrum efficacy, economic advantages, and favorable regulatory profile. It is particularly well-accepted in regions with intensive grain production, large-scale pasture systems, and infrastructure maintenance needs.

Asia-Pacific: Rice and Wheat Dominance

• In China, metsulfuron-methyl is a key component in dry-seeded rice and winter wheat programs, often mixed with bensulfuron or tribenuron.

• In India, it’s commonly used in irrigated wheat fields, targeting broadleaf intrusions such as Chenopodium and Phalaris species.

• Also widely used in Indonesia, Vietnam, and Thailand for early-season weed control in cereal-based cropping systems.

South America: Soy and Pasture Systems

• In Brazil, metsulfuron-methyl is integrated into pre-sowing burndown programs for soybeans and pastures, where it helps suppress aggressive weeds like Ipomoea spp., Euphorbia spp., and Bidens pilosa.

• In Argentina, it’s used in wheat-soy rotation systems and conservation tillage.

Europe & Russia: IPM and Grassland Maintenance

• In the EU zone, metsulfuron-methyl is widely accepted under strict residue and safety regulations. It’s favored in cereal crops, public land vegetation control, and railway systems.

• Russia and Ukraine utilize it for broad-acre wheat programs and steppe zone pasture renewal.

Africa and Middle East: Low-Input Farming and Government Programs

• Used in semi-arid farming systems, especially for low-cost weed control in cereals and public lands.

• Frequently part of government subsidy programs for erosion control and infrastructure vegetation maintenance.

This global diversity of use is supported by metsulfuron-methyl’s low-dose efficiency, multi-crop registration, and shelf-stable formulations, making it adaptable to both high-input commercial farms and extensive, cost-sensitive landscapes.

Frequently Asked Questions About Metsulfuron-methyl

To help you better understand how to use metsulfuron-methyl effectively and safely, here are answers to some of the most common questions from technical users, distributors, and registration professionals.

Q1: Can metsulfuron-methyl be used in dryland (non-irrigated) systems?

Yes. Metsulfuron-methyl is effective in both dryland and irrigated cropping systems. However, for optimal performance, ensure that soil moisture is adequate to support active weed growth at the time of application. Drought-stressed weeds may show slower symptom development.

Q2: Is metsulfuron-methyl compatible with glyphosate in tank mixes?

Absolutely. It is commonly tank-mixed with glyphosate, dicamba, or 2,4-D in burndown and pre-plant programs. This enhances the control of both broadleaf and grassy weeds, and helps in managing herbicide resistance. Always perform a jar test before large-scale mixing.

Q3: Can metsulfuron-methyl be applied during the early seedling stage of crops?

It depends on the crop. In wheat and rice, metsulfuron-methyl can be applied post-emergence once the crop has reached the 2–3 leaf stage, but never during germination. In corn or sensitive crops, it must be used with caution or not at all—follow crop-specific label instructions.

Q4: Is it safe for rotational crops?

Generally yes. Metsulfuron-methyl degrades relatively quickly in soil, but certain rotational crops (like sugar beet, canola, or legumes) may require a waiting period of 3–12 months, depending on dosage and soil conditions. Always consult the product label or a local agronomist.

Q5: What is the re-entry interval (REI) after application?

The standard REI is 12 hours for most formulations, in compliance with WHO and FAO guidelines. Protective clothing should be worn during application and while handling treated plants within this timeframe.

Q6: Can I use metsulfuron-methyl in pasture with grazing livestock?

Yes, it’s registered for use in pastures in many countries. However, grazing restrictions may apply—for example, withholding periods may range from 3 to 14 days depending on local regulations and animal type.

Partner with a Trusted Supplier for Metsulfuron-methyl OEM, Bulk, and Registration Services

Whether you are an agrochemical importer, brand owner, regional distributor, or registration agent, our team offers full-spectrum support to bring Metsulfuron-methyl 60% WDG, 20% WP, and other formulations to your target markets—efficiently, legally, and profitably.

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• Compliant with ISO, FAO, and GMP standards, and supported by independent third-party QC upon request.

Market-Specific Application Guidance

• Tailored usage recommendations by crop, climate zone, and weed species for clients in Asia, South America, Africa, and Eastern Europe.

• On-demand formulation upgrades or co-formulated solutions (e.g., metsulfuron + dicamba) to fit local resistance trends.

By choosing a reliable metsulfuron-methyl manufacturer, you reduce your risk, enhance your brand, and expand your market with confidence.