Winning The Food Plot Weed War

You buy the best seed, plow the perfect plot, and apply fertilizer and lime. But for the best results, plan an attack on weeds.

Kent Kammermeyer | March 7, 2005

Well, you thought you did everything right. Let’s see, you got that soil test, applied recommended lime and fertilizer, plowed vigorously and prepared a smooth seedbed, inoculated your legumes, carefully broadcast your seed, covered lightly and prayed for rain. OK then, why are you standing here now looking at an ugly patch of weeds choking out your deer plot? This is what they neglect to tell you about at the feed-and-seed dealers. Maybe even the county agricultural agent or the wildlife biologist didn’t tell you that weed control is an important but often neglected part of a successful food-plot plan.

Weed control is a very complex subject with a complex answer that varies from one piece of ground to another, depending upon the seed species or root systems already in the soil, the last time it was plowed, and the weather (especially rainfall). There are hundreds of species of weeds, both annual and perennial, ready and willing to jump on your planting and take advantage of all that money you spent on lime and fertilizer.

Why bother controlling weeds? Because they can severely compete with your deer planting and thus lower the production, quality and utilization of your plot. A certain level of weed infestation can be tolerated, depending on what the invader is and what the final product of the target planting is — forage or seed production. Now that the droughts are temporarily gone and we are getting good rainfall, weeds rear their ugly heads even more because conditions are favorable for germination and growth.

Coopers Creek WMA area manager Eric Wood sprays a combination of Poast, ammonium sulfate, and crop oil on a linear clover plot. WRD biologists, like the author, rely on herbicides to get the maximum results from WMA food plots.

This time of year (late winter through mid-spring), you could be dealing with both categories of food plots — a cool-season planting, planted last fall in perennial clover, alfalfa, or trefoil which is now being invaded by warm-season grasses, or with a warm-season planting that will be seeded in April or May with corn, grain sorghum, cowpeas, jointvetch, alyce clover, soybeans, etc. Each has its own set of problems and remedies.

Let’s go through a step-by-step procedure to simplify a complex problem and lead us to the best approach to win the weed wars.

Identify The Enemy

Is the weed a broadleaf or a grass? Is it an annual or a perennial? Was it here last year? If you can’t identify the weed, bring a sample to your Agriculture Extension Agent, University agronomy department, wildlife biologist, or even a nearby farmer. Weed lists are long, even in a single state like Georgia. Here is a short list of some of the most common and worst offenders by category.

Broadleaf weeds include pigweed, ragweed, horsenettle, thistle, jimsonweed, morning glory, milkweed, and coffeeweed (sicklepod). Grasses include fescue, Bermuda grass, johnson grass, crabgrass, foxtail, panicum and many others.

The internet is a great source for helping identify weeds. Go to a search engine like Google and simply type in some of these weed names and you’ll find great websites with pictures and descriptions.

Planning Is Important

In some respects, if you are standing in the weeds in June wondering what to do, it’s too late for some of the best tactics. Which weeds invaded this plot last year? Chances are, it’s the same species you are looking at now. If you planned your plot well last year, you should have heavily influenced what crop is in the field now for the deer — a broadleaf or a grass. In other words, if you have had past weed problems from the grass family, such as crabgrass, then plant a broadleaf (forb) such as clover, jointvetch, trefoil or peas. Vice versa, plant a grass such as grain sorghum (milo) if your weed problem has been a broadleaf. This system allows for selective control with chemical herbicides. In other words, you can get rid of your unwanted weeds by spraying right over the top without killing your food-plot plants. See what I mean by planning? More about selective herbicides later.

Weed-Control Method: Choose Your Weapon

Controlling weeds can be summarized by the three Cs: Cut, Competition or Chemicals. Many deer food plants are highly tolerant of repeated mowing or cutting. These include well-established, cool-season crops like clover, alfalfa, and trefoil. You can often give your plants a competitive edge by mowing the plot, which weakens or kills the weeds (slows down their regrowth) and stimulates quick regrowth of your target plant. This won’t work, however, with peas, beans, or grain sorghum which are warm-season plants that do not respond well to cutting.

By planning ahead, you can also out-compete your weeds using shade. For example, if your weed problem last year was crabgrass, bermuda or fescue, you can plow in early spring, let sit, plow again, and then plant in grain sorghum (10-lbs/acre) or corn (15-lbs/acre), which grow tall and shade out these grasses. Broadcast rate is very important here (5-lbs/acre grain sorghum and 10-lbs/acre corn mixed or 10-lbs/acre grain sorghum by itself). You can even mix in browntop millet (15-lbs/acre) for a three-tiered level of shade and competition. Variety can also be very important. For grain sorghum, use tall-growing, bird-resistant varieties (not WGF, a knee-high plant) for best results. For effective control, you may have to do this shade plot two years in a row to really knock back your grassy weeds.

Of all the options, however, chemicals are often the best choice for your food plot. Chemicals are safe, effective, inexpensive, and cut manpower and plowing tremendously. From this point on, we’ll concentrate on chemicals.

To get started with chemicals, obviously you have to have some spraying equipment. Usually a garden type, two- or three-gallon sprayer won’t do it if your weed problem is fairly extensive or your plot is big. You will quickly find yourself under-gunned. One possible exception is spraying thistle plants or fescue clumps individually if you have 25 or 50 of these isolated plants per acre in clover or other cool-season plots. Roundup or 2,4-D can be used for this.

More likely, if you are serious about food plots, you will need a spray rig for a 4-wheeler or tractor. These are available in electric or gas-driven for 4-wheelers, and electric or PTO-driven for farm tractors. Boom-type sprayers are usually better than rainbow-type sprayers because they minimize drift of spray over non-target plants as well as the operator. Sprayers range in price from $100 to $2,000, depending on size and features.

If you have big fields with good access, you may be able to hire your spraying by truck from a local farm cooperative, seed dealer, or farmer.

What Chemicals to Use

There are hundreds of herbicides on the market. For purposes of this article, we’ll concentrate on three —Roundup (41 percent glyphosate), Poast (sethoxydim) including Poast Plus, and 2,4-D Amine. All of these can be mixed with spreader-sticker (surfactant) and liquid ammonium sulfate (Quest), both products that enhance effectiveness, speed and thoroughness with the weed kill. Glyphosate (also sold under the brand names Clearout, Honcho, Glypro, Razor and others) kills everything. Read the labels for spray rates.

Glyphosate’s best use is as a total kill-back prior to use of a grain drill or traditional renovation plowing and seeding. With glyphosate and a no-till grain drill, you can just about get rid of your disk harrows or plows. This time of year, wait until April and spray glyphosate, wait two weeks, and then drill grain sorghum or cowpeas or jointvetch or alyceclover. If no drill is available, spray, wait two weeks, and then plow and plant realizing that glyphosate will kill all mature plants that it contacts, but the plowing will likely germinate a new crop of weed seeds as it brings the dormant seeds to the surface (although probably reduced in number from the previous crop). As mentioned before, glyphosate can also be used as a spot spray for isolated weed clumps like fescue or thistle.

Poast is a grass-selective herbicide that basically kills all grasses but no broadleafs. It must be mixed with crop oil (an oil-based sticker-spreader) for an effective kill, and ammonium sulfate will make it even better. Read the labels for rates. So, if we are still standing in our food plot in May and the plot is a broadleaf perennial like alfalfa, clover, or trefoil that is being invaded with crabgrass, johnson grass, Bermuda, foxtail, or fescue; then Poast is our weapon of choice. Even new annual broadleaf plantings of peas, beans, clover, or jointvetch are candidates for Poast. This is where last year’s planning pays off. If this plot had problems with crabgrass or johnson grass last year, plow repeatedly and plant a broadleaf. When the noxious grass re-emerges, spray with Poast for the knockout punch. Whichever scenario, if the noxious grasses are over eight-inches tall, mow, wait two weeks and then spray the regrowth. Spray attempts during droughts will be unsuccessful because plants are mostly dormant and will not properly uptake the chemicals. Poast can also be mixed with an insecticide to kill white grubs from June beetles and Japanese beetles. If the ground of your food plot feels soft and spongy or you have lots of moles or cone-shaped skunk diggings, chances are good that you have white grubs feeding on your plant root system. Contact your county extension agent for recommendations.

If broadleaf weeds are the primary concern in your plot, then 2,4-D Amine is a good option that has been around under many brand names for many years. It will not kill grasses. Grain sorghum infested with coffeeweed, ragweed, jimsonweed, morning glory or any other broadleaf qualifies for 2,4-D application. Grain sorghum is a little sensitive to 2,4-D, so read the label carefully. Another great herbicide for grain sorghum or corn is Atrazine, but it is a controlled chemical requiring a private pesticide applicators license. Glyphosate, Poast and 2,4-D are all available over the counter with no license required.

Read The Label

This cannot be emphasized enough. Do not apply any more chemical than the label directs! Use at least 15 to 20 gallons of water per acre for best coverage and effective kills. Do not mix herbicides unless it specifically states this on the label. Carefully calibrate your spraying equipment (your agriculture extension service can help with this) and carefully measure your food-plot acreage. I have seen many half-acre plots that were eyeball estimated to be one acre, thus doubling fertilizer, seed rates, spray rates and everything. It’s a good way to waste money and reduce efficiency, not to mention accidentally killing the good stuff. Poast always needs to be mixed with crop oil. Glyphosate and 2,4-D need to be mixed with a spreader-sticker. Read the labels!

Timing is Everything

Weeds are most vulnerable to chemicals when they are vigorously growing or young, tender seedlings. Do not spray when plants are wet or when rain is expected within 24 to 48 hours. Do not spray when it is windy — drift will render spraying ineffective and can be harmful to the applicator. Again, when weed growth exceeds six to eight inches, mow, wait two weeks and spray regrowth. Do not spray during an extended drought because weed control is ineffective and valuable crop species may be injured or killed.

In summary, chemical herbicides are a safe, effective tool to manage deer food plots. Once equipment is made available, effective chemical applications can be made for $15 to $50 per acre. Counting equipment and manpower costs, you cannot plow any cheaper than this, and every time you plow, you will germinate a new crop of weed seeds to compete with your deer plants. The best of all worlds would be herbicides followed by no-till drilling. Fewer weeds are germinated, soil erosion is greatly reduced, and seed placement is precise. Drilled plots can even be treated selectively with herbicide later as needed for final control. By using chemicals, WRD personnel have maintained vigorous ladino clover stands on WMAs for five to eight years without replanting. These type of results are really efficient and cost-effective. You too can win the weed wars by careful planning and judicious use of chemicals for weed control. The results will surprise you.

For more from biologist and author Kent Kammermeyer, visit his website at

Author’s Note: There are hundreds of other herbicides that can be used on deer food plots. The three above were featured because of my familiarity with them, their name recognition and low toxicity, and because they are easily obtainable and used extensively. Check with your Agriculture Extension Agent for more information.

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