HERBICIDES Back to the Basics

By Jon Cooner

In this issue, we start celebrating the 20th Anniversary of the Whitetail Institute. The last two decades have seen a quantum leap in the knowledge of deer hunters everywhere about food plots. As our knowledge base continues to increase, though, we should never lose sight of the fundamentals, and that is especially true when it comes to herbicides.

In this article, I’ll cover those fundamentals. Along the way, we’ll also discuss some of the major questions that our in-house consultants are asked over and over about herbicides.


Up front, I want to at least remind everyone that herbicides may not be necessary to do certain food-plot jobs. For example, many seedbeds can be cleared of most competing vegetation by disking the seedbed once a week for a few weeks before a fall planting. Also, in many cases weeds can be controlled in existing forages by mechanical means such as mowing or even hand pulling. (Since this article is about herbicides, though, I’ll refer you to our in-house consultants if you’d like additional information on alternatives to herbicides in your particular situation. They’re available from 8:00 a.m. — 5:00 p.m. Central Time, Monday through Friday, at (800) 688-3030, ext. 2. )

Next, I want to clear up something that I think is a constant source of confusion in herbicide discussions: the fact that even though different people may use the same words, those words mean different things to different people. A perfect example is the word “weed.”

Scientists often use the term “weed” based on a plant’s location. To scientists, a “weed” is a plant — any plant — that is growing where it isn’t wanted. The rest of us, though, tend to describe plants in a different way — not by location or desirability, but by what they look like! Here’s an example:

Let’s say that a field tester has Johnsongrass or Bermudagrass infesting his food plot. Since those plants are growing where they aren’t wanted, a scientist might call them “weeds.” Like the rest of us, though, the Field Tester would probably call these plants “grass” because . . . heck, it’s grass! And to make matters worse, many of us also have to deal with additional unwanted plants that we WOULD normally refer to as weeds. These “broadleaf weeds” such as dock or wild mustard, and “woody weeds” such as ferns
or briars.

I’d like to suggest some terms that might get us on the same page as we look at herbicide basics. Let’s dump the term “weed” because it’s unnecessary for our purposes. If we’re even talking about herbicides, we already know that we have plants “growing where we they aren’t wanted.” Instead, since herbicide selection depends so heavily on specific plant identification anyway, let’s establish some better general terms that might help keep confusion to a minimum when you call our consultants for advice, and even keep the scientists happy!

• Suggested Descriptor: “Grass,” Definition: Any plant that looks like grass

• Suggested Descriptor: “Broadleaf Weed,” Definition: Any plant that has wide, fat leaves growing up from the ground without much of a stem or trunk. Examples include dock and wild mustard.

• Suggested Descriptor: “Woody Weed,” Definition: Any unwanted plants that has a hard, woody stem or vine. Examples include ferns and briars.

Now that we’re all using the same lingo, let’s get back to the basics of herbicides for food plotters.


Let’s start with a quick overview of a step-by-step approach you can use to answer the most common questions about herbicides and food plots. Following these steps should help you decide whether or not to use herbicides for your particular food-plot situation, which ones to use and how to use them. Each step is critical, so don’t skip any of them.

Step 1: Identify which of the following two jobs you’re considering using a herbicide for: preparing a seedbed for planting, or maintaining an existing forage.
     a. If you’re preparing a seedbed for planting, choose Roundup, and skip down to Step 3.

     b. If you’re removing unwanted plants from an existing plot, go to Step 2.

Step 2: Specifically identify the plants you want to remove and the plants you want to keep. Then check the herbicide label for the answers to two questions:
     a. Does the label say it will control the plants you want to remove?

     b. Does the herbicide label say that it will not harm the plants you want to keep? If the answer to either question is “no,” don’t use the herbicide for your intended application. If — and only if — the answer to both question is, “Yes,” then you go to Step 3.

Step 3: When applying any herbicide, read and follow all application instructions on the herbicide label. If you have any questions, call our consultants at (800) 688-3030, ext. 2 before you spray.

Next, let’s look at how to apply each of these steps.


When it comes to food plots, there are two reasons herbicides are most often used: (1) to remove unwanted vegetation when preparing a seedbed for planting, and (2) to control unwanted plants in existing food plots. There are literally thousands of herbicides on the market today because there are thousands of potential applications, and each one is unique. That’s why it’s critical to start out by clearly identifying the exact job you’re planning to do.

Herbicides for Seedbed Preparation: One of the steps in our planting instructions is to try to remove as much existing vegetation from your seedbed before you plant. The best known product for accomplishing that is Roundup Weed and Grass Killer, a non-selective herbicide whose active ingredient is glyphosate, or “gly” as you may hear it called in conversations. In recent times, numerous generic equivalents have also appeared on the market, so for simplicity, I’ll just refer to all these as “Roundup” from here on. One reason Roundup is such an effective tool for cleaning up a seedbed before planting is that it is “nonselective” — it has at least some effect on almost any plant it touches. Another feature that makes Roundup appropriate for preparing a seedbed is that it doesn’t have residual soil activity — it doesn’t stay around in the soil and inhibit the growth of your new forage plants. Instead, whatever Roundup you spray that does not go into a plant dissipates very quickly. The Roundup label says how long you have to wait after spraying before you plant, but 10 days is a pretty safe bet.

Herbicides for Perennial Forage Maintenance: Unlike controlling all vegetation as a part of seedbed preparation, forage maintenance suggests that you want to keep existing forage plants and eliminate competition. That requires the use of a herbicide specifically designed to control unwanted plants without harming the ones you want to keep. Herbicides that do that are referred to as “selective herbicides.” Before deciding to use a selective herbicide, it is absolutely critical that you check the herbicide label and make sure that the herbicide will do two things: (1) control the specific plant varieties you don’t want, and (2) do it without harming the forage plants you want to keep. Let’s look at each in turn.


Herbicides generally do their jobs by interfering with one or more of a plant’s essential life processes, for instance the way a particular plant grows or reproduces. The ways different plant types do these things, though, can be quite different from one type of plant to the next. For example, some plants reproduce by making seeds and dropping them on the ground, creating the next generation. Others, though, may reproduce by spreading their roots out underground.

This wide variety in how plants of different types survive, grow and reproduce is what makes selective herbicides possible. Basically, it allows scientists to narrowly tailor chemicals to control certain types of plants without harming others.

For example, consider a corn farmer who needs to control grass in his corn crop. He will select a herbicide that will control the grass but not harm the corn. Since he knows, though, that selective herbicides are designed to control some plants and not others, he’ll make sure that the herbicide he’s considering will (1) control the specific type of grass he wants to remove, and (2) not harm the specific type of corn he is growing. There are three steps to doing that, and they are the same steps we use in choosing selective herbicides for use in our food plots.

First, identify the plants you want to control.Remember I said that selective herbicides work by interfering with the essential life processes of specific plant types, and that these processes are often quite different from one plant type to the next? Since selective herbicides are designed to work on the specific systems of certain plants, your first step in deciding on a herbicide to meet your needs is to identify — specifically identify — the plants you want to control.

There are several good ways to do that. One way is by looking up the plant on any number of free web sites that deal with plant identification. These sites are provided on the websites of many major ag-university website and also the U.S. Department of Agriculture. Many of these sites, though, list plants by name rather than by picture, and that can be of limited benefit to those of us who already know what the plant looks like but don’t know what it is.

In such cases, you might turn to two great resources in our area. These are your county agricultural agent and your local farm-supply store. Your county agent will likely be able to accurately identify most plants growing in your area. Your farm-supply store manager is also likely very familiar with plant-control issues that face farmers in your area.

Second, identify the plants you want to keep. Imperial forage blends come with a sticker on the back that tells you what’s in the blend. If you don’t have the bag any longer, you can call our consultants for the information.

Third, consult the herbicide label. Once you have specifically identified the plants you want to control and those you want to keep, look at the herbicide label. It will give you specific lists of the plants it will and won’t control. You need to make sure that the label specifically says it will control the plants you don’t want and that it won’t hurt the
plants you want to keep.

Whitetail Institute Herbicides: The Whitetail Institute currently offers two selective herbicides. Arrest is designed to control most kinds of grass in any Imperial perennial blend, and any other clover or alfalfa. Slay is designed to control broadleaf weeds in Imperial Whitetail Clover and any other clover or alfalfa. This is not an exclusive list of forages these herbicides can be used on. For additional information on Arrest and Slay, call our consultants at (800) 688-3030, ext. 2, or go to www.whitetailinstitute.com, and click on the “Herbicides” link.


Most of us have cut corners at some point in our lives. For example, when I was just starting out planting food plots for myself, I didn’t understand the importance of adjusting soil pH with lime and tried to compensate for low pH by just adding more fertilizer. Now that I do understand more about soil pH, I can see why I sometimes got less than stellar results from my early planting efforts.

Thanks to the fact that deer hunters are generally a pretty honest lot, I still see the same thing occasionally. On the rare occasion when a Field Tester calls with a problem that’s not related to lack of rain, the most common reason — by far — is that he admits having skipped steps in our planting instructions.

And if you think about it, it just makes sense to follow the manufacturer’s directions concerning any product. After all, each step is important, or it would not be there. This is true of planting instructions for food-plot blends, and this is true of the instructions on herbicide labels.

In fact, it’s especially true when it comes to herbicides. If you look at any herbicide label, you’ll probably find that different instructions are given for different jobs the herbicide can be used for.

For example, Arrest and Slay are generally designed to offer the best control of some plants when they’re still in seedling stage, and the labels give specific instruction on how to use the herbicides in that case. Arrest and Slay can also be very effective at controlling more mature plants, but to do so requires that you follow a different set of label instructions.

The label instructions are there for only one reason: so that the manufacturer of a herbicide can tell you what it knows — the best way to use that herbicide to do the job you’re facing. And since failing to follow the label directions may give you less than a good result from the herbicide, it just makes sense to follow herbicide label directions exactly.

And that brings us to the most commonly asked questions presented to our consultants — the questions that come in over, and over. Almost always, the answer is provided right on the Arrest or Slay label.

Q: Which Imperial products can be sprayed with Arrest and Slay, and which ones can’t?

A: Here’s a list of Imperial forages and whether the plant varieties in each can be sprayed with either herbicide. This list does not address additional issues discussed on the label, such as temperatures, plant dormancy, soil residuals and other issues. Arrest CAN BE USED on: ImperialWhitetail Clover, Chicory Plus, “Chic” Magnet, Alfa-Rack, Alfa-Rack Plus, Extreme and Winter-Greens. Slay CAN BE USED on: Imperial Whitetail Clover and Alfa-Rack. Arrest SHOULD NOT BE USED on: No-Plow, Pure Attraction, PowerPlant or Secret Spot. Slay SHOULD NOT BE USED on: Chicory Plus, “Chic” Magnet, Alfa-Rack Plus, Extreme, No-Plow, Winter-Greens, Pure Attraction, PowerPlant or Secret Spot.

Q: Can Arrest and Slay be mixed in the same tank and sprayed at the same time?

A: No. Doing so will reduce the effectiveness of the Arrest by 50% or more.

Q: When is the best time to spray Arrest or Slay?

A: Spray when weeds and grasses are actively growing in the spring or summer. Arrest and Slay are designed to work best at controlling seedling grasses and broadleaf weeds (those that are still too young to have grown taller than 6-12”). Try to spray before grasses or weeds exceed that height if possible.

Q: When should I not spray Arrest or Slay?

A: Do not spray within one week after mowing the plot. Do not spray when conditions are excessively hot or droughty. This is not a complete list. Consult the herbicide labels for additional information.

Q: Can Arrest and Slay control grasses and broadleaf weeds that have matured?

A: Yes, but it will be harder to do.When trying to control mature grass with Arrest, use the highest concentration on the label, add Surefire Seed Oil to the tank, and plan on having to spray twice, a month apart. You may not have to spray twice, but you might.

Q: If my grass and broadleaf weeds have matured taller than 6-12”, should I mow before spraying?

A: It can help. Mowing won’t make the plants young again. The key is the age (size) of the root ball — a mature plant that’s mowed may be shorter, but its root ball is still mature. However, when you mow a plant, it usually grows vigorously to recover its lost forage, and that can help the herbicide get into the plant. If you mow, don’t spray for a week afterwards or until you see new growth appearing, whichever occurs first. That’s because mowing may put the plant into shock, and it has to recover and start growing again before it will take in the herbicide.

Q: How long must Arrest and Slay be on the plants before rain won’t wash them off?

A: According to the labels, one hour. I try to spray in mid-morning on a day when I don’t expect rain until at least after nightfall.

Q: I have weeds in my ImperialWhitetail Clover plot.Will Arrest or Slay control them?

A: It depends. To answer this question, you have to identify the weed. Once you do that, you’ll be able to check the Arrest and Slay labels to see if either says it will control it.