Food Plot Weed Control: Spraying Clover Without Killing It

Here is the constraint that makes food plot weed control a different problem from lawn weed control, and it is not about scale.

Clover is a broadleaf plant. So a broadleaf herbicide kills your clover along with the weeds. Same for alfalfa. It is exactly the trap that makes a clover lawn unsprayable — except here the clover is the crop and giving up on control is not an option.

Three chemistries work around it, and one job matters more than all three.

The Pre-Plant Kill Matters Most

Most plots are lost before they are planted, and Arkansas Extension puts the condition plainly:

“No-till seeding methods may be successful if herbicides are used to kill existing sod and control other grass competition.”

That conditional carries the whole approach. The existing vegetation is not background — it is the competition, established, rooted and already occupying the light and water your seedlings need. Drilling into living sod without removing it first is a race your seedlings lose.

On tilled ground the disking does this mechanically, and Arkansas notes one clear advantage: “studies indicate that planting warm-season grasses on a tilled seedbed is the best planting method.” So the choice is not spray-versus-till so much as remove the competition one way or the other.

Use a systemic for it, not a burndown. NC State’s distinction is the one that decides the outcome, because the target here is established perennial sod rather than seedlings. They group the contact products together — diquat, pelargonic acid, glufosinate, fatty acids, acetic acid, botanical oils — and state they “will only knock down the top growth of perennial weeds”, with glufosinate specifically “does not translocate to the roots of treated plants.”

A contact product on a perennial sod is a mowing. A systemic reaches the roots.

And one thing no product on either list does: NC State notes “none of these products have residual activity (i.e.: no root uptake and no preemergence weed control) in soils.” So the seedbank germinates alongside your crop regardless. That is normal rather than a failure, and mowing is usually the right response to the first flush.

Killing Grass In A Legume Stand

The easier of the two in-crop problems, because the chemistry is clean.

Clethodim is an ACCase inhibitor — a mode of action that targets grasses specifically. It is genuinely selective rather than rate-dependent, so a rate that removes crabgrass, foxtail and volunteer cereal leaves clover, alfalfa and brassicas standing.

This is the mirror image of every product on the rest of this site. Lawn herbicides spare grass and kill broadleaves; clethodim spares broadleaves and kills grass.

Do not put the two in one tank. NDSU Extension: most broadleaf herbicides tank mixed with post-emergence grass herbicides reduce grass control compared with the grass herbicide alone. Spray the clethodim a day before the broadleaf product, or wait seven days if the broadleaf went on first — mixing herbicides in one tank has the intervals and the 30-day wait before seeding a grass crop afterwards.

The adjuvant is where results are lost. Most clethodim labels call for an oil-based adjuvant rather than a plain nonionic surfactant, and substituting the surfactant you already own is the usual cause of a spray that browned the grass and did not kill it. Read that line before mixing. Our sprayer guide covers why the rest of the application — constant pressure, nozzle, calibration — decides whether the label rate is what actually lands.

Killing Broadleaves In A Broadleaf Crop

This is the one that sounds impossible, and the mechanism is worth understanding because it explains the label restrictions.

2,4-DB is applied in a form that is not strongly herbicidal on its own. Plants metabolise it into the active compound — and legumes such as clover and alfalfa do that far more slowly than many broadleaf weeds do. The weed converts enough to poison itself; the legume largely does not.

Which is why the timing window is the product. Selectivity depends on the growth stage of both the crop and the weed, so the label’s window is not advisory — spraying outside it is where crop injury comes from. That is a different kind of instruction from a lawn herbicide’s temperature limit, and it deserves more attention than it usually gets.

The second option in this slot is imazethapyr, which is also selective in legumes:

The Residual Trap

Three molecules, three completely different answers to “when can I plant?” — and the names are close enough that people mix them up.

Imazethapyr and imazapyr differ by three letters and behave nothing alike. Imazethapyr is the legume-selective in-crop product above. Imazapyr is a total bare-ground herbicide — if a listing mentions bare ground or site preparation, it is the wrong one, and using it on a plot means nothing establishes there for the better part of a year.

Full timing detail for the glyphosate case is in how long after Roundup can I plant grass — the short version is that the wait is for a confirmed kill, not for the chemical to clear.

What Mowing Does And Does Not Do

The cheapest tool, and worth being precise about.

Mowing works against upright annual weeds that need height to set seed, and a clover or alfalfa stand tolerates being cut. Cutting before weeds seed reduces next year’s population, which is the same logic pasture guidance uses.

Mowing does not work on grasses that grow below the cutting height, or on perennials that regenerate from roots and rhizomes. Cutting those is maintenance, not control — the same conclusion our pasture guide reaches from the grazing side.

So the division of labour is: mow to stop seed set, spray for what mowing cannot reach, and expect a first-year plot to need more of both than an established one.

Everything Above Assumes A Legume

The three chemistries on this page exist because clover and alfalfa are legumes. Plant something else and the answers change completely — in two cases, they invert.

• A cereal plot is a grass plot, so clethodim would kill the crop while 2,4-D becomes the labelled option — with one clause about legumes that rules out most mixed plantings. That is weed control in cereal food plots.
• A brassica plot faces weeds from its own family, and nothing selective separates a wild mustard from a turnip. See weed control in brassica food plots.

The Sequence

What This Page Is Not

On the pasture side of the same shelf, best pasture weed killer sorts the products by weed and names the grazing intervals that decide which ones you can use at all — including the reason a legume plot needs 2,4-DB rather than 2,4-D.

Worth stating, because the chemistry above overlaps with agriculture.

These are plot and paddock products at plot and paddock scale, on labels written for legume stands and wildlife plantings. They are not row-crop agronomy: corn, soybean and cereal weed control is a licensed-applicator field with its own products, its own resistance management and its own economics, and the guidance a farmer needs is not the guidance here.

Nor do they transfer to a lawn. In a lawn, clover is a minority component you cannot spray around — which is exactly why our clover guide reaches the opposite conclusion from this page. Same plant, different crop, different answer.