Cyhalofop-butyl Mode of Action: How This ACCase Inhibitor Controls Grassy Weeds

What is Cyhalofop-butyl?

Cyhalofop-butyl is a selective post-emergence herbicide designed to control tough annual and perennial grassy weeds in crops like rice.
Belonging to the arylphenoxypropionate (FOP) class of herbicides, it works by targeting the ACCase enzyme that grasses need to grow — providing effective knockdown of weeds like barnyardgrass, junglerice, and other troublesome grasses, without harming your crop when used correctly.

Because of its crop selectivity and consistent performance, cyhalofop-butyl has become a trusted tool for growers looking to protect yields and maintain clean paddies or fields.

Mode of Action: How Cyhalofop-butyl Works

Cyhalofop-butyl works by inhibiting the ACCase (Acetyl-CoA Carboxylase) enzyme, which is essential for fatty acid synthesis in grassy weeds.
In simple terms, this enzyme is like the “fuel refinery” that weeds need to build new cell membranes and grow. When cyhalofop-butyl blocks ACCase, the plant can’t produce the fatty acids it needs — its cells break down, growth stops, and the weed gradually withers and dies.

This mode of action is highly effective against small-seeded annual grasses like barnyardgrass, jungle rice, and wild millet, which are common problems in rice paddies and other cereal fields.
One big advantage is crop selectivity: broadleaf crops and rice plants can metabolize cyhalofop-butyl quickly, rendering the herbicide inactive within the crop while it remains lethal to target weeds.
That’s why, when applied correctly and at the right timing, cyhalofop-butyl provides excellent grass control with minimal crop stress.

However, like all ACCase inhibitors (FOPs and DIMs), overuse or repeated solo application can encourage resistant grass biotypes. That’s why understanding how it works helps growers rotate or mix modes of action to keep this tool effective year after year.

Application Best Practices

To get the most out of cyhalofop-butyl, timing and technique matter just as much as its powerful mode of action.
This herbicide is best applied post-emergence, targeting grassy weeds when they’re at the early seedling stage — typically when weeds have 2–4 leaves.
Treating weeds at this young stage means the ACCase inhibition works more effectively, as the plants haven’t yet developed the reserves to survive a blocked fatty acid pathway.

Soil and weather conditions also play a role:

• Apply when soil moisture is adequate to support active weed growth — stressed or dormant weeds won’t absorb the herbicide as well.

• Avoid applications just before heavy rain to prevent wash-off.

• Use a uniform spray with the correct droplet size to ensure good leaf coverage, especially since cyhalofop-butyl works mainly through leaf absorption.

For broad-spectrum control, cyhalofop-butyl is often tank mixed with a compatible broadleaf herbicide — this helps control mixed infestations and reduces the chance of resistant grass species escaping.
Always check label recommendations for approved tank-mix partners and follow any adjuvant or surfactant requirements to boost performance.

Proper application not only maximizes control of weeds like barnyardgrass and junglerice but also helps protect your crop from yield loss and competition stress.

Resistance Management

Like other ACCase inhibitors, cyhalofop-butyl is a powerful tool — but relying on it alone season after season can lead to resistant grass weed populations.
Over time, repeated use of the same mode of action can select for biotypes that survive ACCase inhibition, especially in tough species like barnyardgrass (Echinochloa spp.) and junglerice.

Good resistance management practices include:

• Rotate modes of action: Use herbicides with different targets in your weed control program. For example, alternate cyhalofop-butyl with ALS inhibitors, PS II inhibitors, or non-selective options when possible.

• Use full, label-recommended rates: Underdosing weeds can encourage survivors and seed set.

• Mix when practical: Tank mixing cyhalofop-butyl with a compatible broadleaf or residual herbicide adds another mode of action to your program — widening the spectrum and lowering resistance pressure.

• Integrate non-chemical controls: Don’t forget cultural methods like field sanitation, water management in paddies, and crop rotation — they help limit weed seed banks and break resistance cycles.

A proactive plan helps you protect cyhalofop-butyl’s effectiveness — ensuring it remains a reliable option for grass weed control in rice and other crops for years to come.

Conclusion: Why Understanding Cyhalofop-butyl’s Mode of Action Matters

Cyhalofop-butyl’s precise mode of action as an ACCase inhibitor gives growers a valuable edge in controlling some of the toughest grassy weeds that threaten rice and other crops.
By blocking fatty acid synthesis where it matters most, this selective herbicide stops weeds like barnyardgrass and junglerice in their tracks — without putting unnecessary stress on your crop.

But a mode of action is only as effective as the way it’s used. Applying cyhalofop-butyl at the right growth stage, under the right field conditions, and alongside smart resistance management ensures you get the best results today — and preserve its value for tomorrow.

Whether you need consistent supply, bulk packaging, or customized formulation and labeling for your region, partnering with a trusted manufacturer makes all the difference.
Ready to keep your fields cleaner, your yields stronger, and your weed control plan future-proof?
Let’s talk about how a reliable cyhalofop-butyl solution can fit your operation.