Imazethapyr is one of the most effective and widely studied selective herbicides for killing weeds in clover without killing the clover itself, and bentazone is another reliable option for broadleaf weed control within clover stands. The challenge is that clover is a broadleaf legume, which means the standard broadleaf herbicides used in grass lawns and pastures will damage or destroy it alongside the weeds. Choosing the right spray requires understanding which chemicals the clover can tolerate and which weeds you are targeting.
Why Most Common Herbicides Are Off the Table
If you have ever sprayed a grass lawn to kill dandelions or plantain, you probably used a product containing 2,4-D, dicamba, or triclopyr. These work by exploiting a biological difference between grasses and broadleaf plants. Grasses shrug them off; broadleaf weeds absorb the chemicals and die. The problem is that clover is also a broadleaf plant. Spray a typical “weed and feed” product over your clover stand, and the clover will suffer the same fate as the dandelions.
This is the central frustration of weed control in clover, whether you are managing a food plot, a pasture, a microclover lawn, or a cover crop. You cannot simply reach for the most popular broadleaf herbicide on the shelf. You need herbicides that are selectively tolerated by clover or that target only the grass weeds growing among it. Those options exist, but they are fewer and more specialized than what most people are used to.
It is also worth knowing that chelated-iron products, sometimes marketed as “natural” or organic lawn treatments, are effective at killing clover and dandelions in turfgrass with minimal injury to the grass itself. That makes chelated iron the opposite of what you want here. If your goal is to preserve the clover, keep chelated-iron sprays away from it.1International Turfgrass Society Research Journal. Efficacy of natural herbicides on dandelion (Taraxacum officinale G.H. Weber ex Wiggers) and white clover (Trifolium repens L.) populations
Post-Emergent Herbicides That Clover Can Tolerate
The short list of herbicides that kill weeds without destroying clover falls into two categories: those that target broadleaf weeds selectively enough that clover survives, and those that target only grasses.
Imazethapyr for Broadleaf and Grass Weeds
Imazethapyr, often sold under the trade name Pursuit, is the closest thing to an all-purpose herbicide for clover. Research on Egyptian clover found that it controlled both grass and broadleaf weeds when applied either before or after weed emergence, and was safe on the clover at standard rates.2Crop Protection. Herbicide effect on weed control, soil health parameters and yield of Egyptian clover (Trifolium alexandrinum L.) – Section: Conclusion Trials in Alberta confirmed imazethapyr’s potential for weed control across several forage legumes, including berseem clover, balansa clover, and alfalfa.3Canadian Journal of Plant Science. Tolerance of annual forage legumes to herbicides in Alberta – Section: Abstract And a study testing white clover at various growth stages found it tolerant to imazethapyr at standard application rates.4African Journal of Agricultural Research. White clover tolerance to herbicides applied at different rates and phenological stages – Section: Results and Discusion
Imazethapyr works by inhibiting an enzyme that plants need to produce certain amino acids. Many legumes happen to tolerate it well, which is why it shows up repeatedly in clover and alfalfa research. For someone managing a clover food plot or pasture with a mixed weed problem, it is usually the first herbicide to consider.
Bentazone for Broadleaf Weeds
Bentazone, sold as Basagran and other trade names, is another post-emergent option that clover tolerates. Research on white clover seed crops found that bentazone showed the least toxicity to plant growth, nodulation, and nitrogen fixation compared with other commonly used herbicides in those settings.5Soil Biology and Biochemistry. Influence of herbicides on growth and nodulation of white clover, Trifolium repens – Section: Abstract Bentazone is particularly useful against broadleaf weeds like chickweed. Trials combining bentazone with benazolin, another broadleaf herbicide, showed improved control of common chickweed in white clover leys without significant harm to the clover or the companion ryegrass.6Weed Research. Improved control of Stellaria media (L.) Vill in leys with Trifolium repens, using bentazone and benazolin with additives – Section: Abstract
The tradeoff is that bentazone works mainly on broadleaf weeds. If your clover is being invaded by crabgrass, foxtail, or other grassy weeds, bentazone alone will not solve the problem.
Grass-Specific Herbicides
When the weed problem is grasses rather than broadleaves, the solution is a graminicide, a herbicide that kills only grasses. Products containing clethodim, sethoxydim, or quizalofop-ethyl are designed to eliminate grass species while leaving broadleaf plants untouched. Research on Egyptian clover found that a program using alachlor as a pre-emergent followed by quizalofop-ethyl as a post-emergent spray was effective at controlling weeds.2Crop Protection. Herbicide effect on weed control, soil health parameters and yield of Egyptian clover (Trifolium alexandrinum L.) – Section: Conclusion Since these herbicides target a metabolic pathway found only in grasses, they pose essentially no risk to clover.
For many clover growers, a two-pronged approach works best: a graminicide for the grass weeds and imazethapyr or bentazone for the broadleaf weeds. In mixed-weed situations, this combination covers far more ground than any single product.
Pre-Emergent Sprays and Why They Often Disappoint
Pre-emergent herbicides kill weeds as they germinate, before they break through the soil surface. They sound ideal, but they have a rough track record in clover. Research evaluating pre-emergent applications on establishing stands of alfalfa, white clover, and crownvetch found that none of the pre-emergent herbicides tested provided good weed control without also causing severe injury to the legumes.7Agronomy Journal. Evaluation of Herbicides in the Establishment of Alfalfa, Ladino White Clover, and Crownvetch – Section: Abstract The difficulty is that the same germination-inhibiting chemistry that stops weed seeds also interferes with clover seedlings trying to establish.
There are exceptions. Alachlor used as a pre-emergent was part of a successful weed-control program in Egyptian clover, though it was paired with a post-emergent graminicide to complete the job.2Crop Protection. Herbicide effect on weed control, soil health parameters and yield of Egyptian clover (Trifolium alexandrinum L.) – Section: Conclusion And imazethapyr can be applied pre-emergence in certain clover species. But as a general rule, if you are seeding clover for the first time and want to control weeds with a spray, you will have better luck waiting until the clover has established and then applying a post-emergent herbicide. Pre-emergent applications are riskier during that vulnerable seedling stage.
Timing Matters More Than You Might Expect
Even herbicides that clover tolerates can cause significant damage if applied at the wrong time. Research on white clover found that tolerance increased with plant age. Young seedlings at the three-leaf stage were far more susceptible to herbicide injury, and some rates that mature plants shrugged off were lethal to seedlings. Specifically, white clover tolerated low rates of 2,4-D and even low rates of glyphosate, but the same rates that caused only temporary phytotoxicity in older plants killed seedlings outright.4African Journal of Agricultural Research. White clover tolerance to herbicides applied at different rates and phenological stages – Section: Results and Discusion
The practical takeaway is straightforward: let your clover get established before you spray anything on it. A clover stand with several sets of trifoliate leaves and a developing root system can handle herbicide stress that would destroy a freshly germinated seedling. If weeds are already a problem during establishment, mechanical methods like hand-pulling or mowing above the clover canopy are safer than reaching for a spray bottle too soon.
Environmental conditions also play a role. Soil moisture, temperature, and nitrogen levels in the soil can all alter how a particular herbicide behaves on clover. A spray that works well on a moist day in spring could cause unexpected damage during dry summer heat, because the clover is already under stress and has less metabolic capacity to detoxify the herbicide. Read label instructions for temperature and moisture windows, and avoid spraying clover when it is already showing signs of drought stress or heat damage.
Herbicides Can Hurt Clover’s Nitrogen Fixation Even Without Visible Damage
One of the main reasons people grow clover is its ability to fix atmospheric nitrogen through a symbiotic relationship with soil bacteria that colonize its roots. Herbicides can disrupt this process even when the clover itself looks healthy above ground. Research testing five common herbicides on white clover found that most of them inhibited nitrogen-fixing activity, reduced nodule numbers, or lowered plant weight. Bentazone showed the least toxicity to nitrogen fixation under controlled conditions, while paraquat was the most harmful to the symbiotic bacteria.5Soil Biology and Biochemistry. Influence of herbicides on growth and nodulation of white clover, Trifolium repens – Section: Abstract
Research on red clover and the herbicide dinoseb showed a similar pattern. Dinoseb reduced nitrogen-fixing enzyme activity for up to 18 days after treatment, even though it ultimately increased yields compared with unweeded controls because removing the weeds was still worth the temporary hit to nitrogen fixation. The researchers found that dinoseb did not act directly on the root nodules but damaged the photosynthetic parts of the plant, which indirectly starved the nitrogen-fixing bacteria of energy.8Soil Biology and Biochemistry. Effect of dinoseb on nitrogen fixation of red clover (Trifolium pratense) – Section: Abstract
This is an underappreciated consideration. If you are growing clover partly or entirely for its soil-building benefits, you want a herbicide that minimizes disruption to nitrogen fixation, not just one that keeps the clover alive. Bentazone comes out well on this front. And in many cases, the math still favors spraying: a clover stand choked with weeds is fixing less nitrogen than a sprayed stand with temporarily reduced fixation but no weed competition. Still, it is worth knowing that a herbicide-treated clover stand is not functioning at full capacity for a couple of weeks after application.
Getting the Spray to Actually Work on Weeds
The effectiveness of any spray depends partly on whether the droplets stay on the weed leaf long enough to be absorbed. Different weeds have different leaf surfaces, some waxy and water-repellent, others covered in fine hairs, and these surfaces interact with spray droplets in ways that can make or break your application.
Research comparing adjuvant types found that the choice of surfactant dramatically affects how well spray droplets spread and stick. On hairy leaf surfaces, droplets containing a crop oil concentrate sat on top of the hairs without wetting the leaf surface underneath, essentially bouncing off. Modified seed oil and oil-surfactant blends performed far better, spreading extensively across hairy leaves until they dried. On waxy leaves, non-ionic surfactants and modified seed oils produced larger wetted areas than crop oil concentrates.9PubMed. Droplet evaporation and spread on waxy and hairy leaves associated with type and concentration of adjuvants
For clover growers, the practical lesson is that adding the right surfactant or adjuvant to your spray tank can make a real difference, especially against hard-to-wet weeds. Research on bentazone and benazolin in white clover leys specifically found that oils and surfactants increased the rate at which bentazone entered the leaves of target weeds like common chickweed, without meaningfully increasing toxicity to the clover or companion ryegrass.6Weed Research. Improved control of Stellaria media (L.) Vill in leys with Trifolium repens, using bentazone and benazolin with additives – Section: Abstract In other words, the adjuvant helped the herbicide get into the weed faster while the clover remained relatively unharmed. Check your herbicide label for compatible adjuvant recommendations, and when in doubt, a non-ionic surfactant is a safe default for most post-emergent applications.
Cultural Practices That Reduce the Need to Spray
Spraying is not the only way to keep weeds out of clover, and in many cases it works best as a complement to good management rather than a standalone solution. Dense seeding is one of the most effective non-chemical tools. Research on white clover establishment found that sowing at a high rate produced a ground cover that suppressed weed invasion much more effectively than sparse seeding. When clover was seeded thinly or late in the season, winter annual weeds like shepherd’s purse moved in and established before the clover could fill the gaps.10J-STAGE / Journal of Weed Science and Technology. Effects of Seeding Methods and Mowing on the Establishment of White Clover (Trifolium repens L.) Cover for Weed Suppression – Section: Abstract
Mowing is another important tool. Setting your mower high enough that it clips the tops of tall weeds without scalping the clover gives the clover a competitive advantage. Most clovers stay low to the ground, while many common weeds grow upright. A well-timed mowing removes the weeds’ canopy while leaving the clover’s growing points untouched. Over time, repeated mowing favors the clover and weakens the weeds.
Soil fertility management also plays a role, though it works differently than you might assume. Because clover fixes its own nitrogen, adding extra nitrogen fertilizer to a clover stand can actually help grasses and broadleaf weeds outcompete the clover. Keeping nitrogen inputs low in a clover stand gives the clover its natural advantage: it can thrive in lower-nitrogen soils where many weeds cannot.
Watch for Herbicide Carryover If You Are Planting Clover Into Crop Ground
If you are planting clover as a cover crop after a summer cash crop, residual herbicides left in the soil from the previous season can injure or kill your clover before it even gets started. Research on fall-planted cover crops found that while grass cover crops were rarely affected by herbicide carryover, certain residual herbicides from the previous growing season did affect the establishment of broadleaf cover crops including crimson clover.11Weed Technology. Herbicide carryover to various fall-planted cover crop species – Section: Abstract
The tricky part is that carryover injury often shows up as stunted or uneven germination, which can look like a seeding problem rather than a chemical one. If you applied a long-residual herbicide like certain sulfonylureas, triazines, or Group 2 (ALS-inhibiting) herbicides to a corn or soybean crop, check the herbicide label for plant-back restrictions before seeding clover. Many labels specify a waiting period, sometimes several months, before sensitive broadleaf crops or cover crops can be planted. Ignoring those restrictions is one of the most common and preventable causes of clover establishment failure.
A Quick Reference for Common Scenarios
Because the right spray depends on your situation, here is how the options break down by weed type and clover setting:
- Grass weeds in clover: A graminicide like clethodim, sethoxydim, or quizalofop-ethyl will kill grasses while leaving clover untouched. These are the safest option for clover stands invaded by crabgrass, foxtail, or volunteer cereals.
- Broadleaf weeds in clover: Imazethapyr or bentazone are the primary options. Imazethapyr handles both broadleaf and grass weeds at standard rates. Bentazone is gentler on nitrogen fixation and works well against weeds like chickweed.
- Mixed weed problems: Combine a graminicide for the grasses with imazethapyr or bentazone for the broadleaves, applied separately per label directions.
- New clover seedings: Wait until the clover is well established before spraying. Pre-emergent herbicides have a poor track record during clover establishment. Focus on dense seeding and mowing early on, and reserve herbicide applications for after the clover has several trifoliate leaves.
- Clover in a mixed grass-clover pasture or lawn: Be aware that graminicides will kill the grass component too. In these settings, bentazone for broadleaf weeds is often the only spray option that preserves both species. For grass weeds in a grass-clover mix, selective mowing and overseeding are more practical than any spray.
Always check the specific herbicide label for your clover species and your state or province’s registration requirements. Herbicide labels are legal documents, and a product registered for use on one type of clover may not be registered for another. White clover, red clover, crimson clover, and berseem clover each have slightly different tolerance profiles, and rates that are safe for one species can cause damage in another.