Winning the Weed Wars in Your Food Plots

By: Kent Kammermeyer

Well, you thought you did everything right. Let’s see, got that soil test, applied recommended lime and fertilizer, 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 forgot to tell you about at the seed dealers. Maybe even the county agricultural agent or the wildlife biologist didn’t tell you.

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

Why control weeds? Because they can severely compete with your deer planting for moisture and light and thus lower the production, quality, and utilization. A certain level of weed infestation can be tolerated, depending on who the invader is and whether the objective of the target planting is forage or seed production.

This time of year, you could be dealing with both categories of food plots—a cool season planting, planted last fall in clover, alfalfa, or trefoil which is now being invaded by warm season grasses or a warm season planting, planted in May or June with corn, grain sorghum, peas, jointvetch, alyce clover, soybeans, etc. Each has its own set of problems and remedies we’ll discuss later.

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

1. Identify The Enemy. Is it a broadleaf or a grass? Is it an annual or a perennial? Was it here last year? If you can’t identify the weed, take a sample to your agriculture extension agent, university agronomy department, wildlife biologist, or even a nearby farmer. Weed lists are long. Here is a short list of some common offenders by category. Broadleaf weeds include pigweed, ragweed, horsenettle, thistle, jimsonweed, morning glory, milkweed, and coffeeweed. Grasses include fescue, bermudagrass, johnsongrass, crabgrass, foxtail, and many others.
2. Planning Is Important. In some respects, if you are standing in the weeds in mid-summer wondering what to do, it’s too late for some of the best tactics. What weeds invaded this plot last year? Chances are it was the same species. Your observation of weeds from last year should have influenced what crop you planted this year—a broadleaf or a grass. In other words, if you have had past weed problems from the grass family, such as crabgrass, plant a broadleaf such as clover, jointvetch, or peas. Vice versa, plant a grass such as grain sorghum if your weed problem is a broadleaf. This system allows for selective control of your weeds with chemical herbicides without killing your target planting. See what I mean by planning? More about selective herbicides later.
3. Control Method (choose your weapon)—Cut, Competition or Chemicals. Many deer food plants are highly tolerant of repeated mowing or cutting. These include clover, alfalfa, and trefoil. You often can give your plants a good competitive edge by mowing, which weakens or kills the weeds and stimulates regrowth of your target plant. This won’t work, however, with peas, beans, or grain sorghum which do not respond well to cutting.

   By planning ahead, you can 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 plant in grain sorghum or corn, which grow tall and shade out these grasses. Broadcast rate is important here (5 lbs/acre grain sorghum and 5 lbs/acre corn mixed or 10 lbs/acre grain sorghum by itself). Plant variety is also important. For grain sorghum, use tall growing bird resistant varieties (not WGF) for best results.

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

4. Getting 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. You will quickly find yourself “under-gunned.” One possible exception is spraying individual thistle plants or fescue clumpsin 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 four-wheeler, pickup truck, or tractor. These are available in electric or gas driven for four-wheelers and electric or PTO driven for tractors. Boom type sprayers with fan nozzles are usually better than rainbow type sprayers. Sprayers range in price from $150 to $2,000, depending on 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.

5. What Chemicals to Use. There are hundreds of herbicides on the market. For purposes of this article, we’ll concentrate on three—Roundup®, Poast®, and 2,4-D. Roundup kills a broad range of both grasses and broadleaves. Its best use is to control unwanted vegetation prior to the use of a grain drill. With Roundup and a no-till grain drill, you can just about get rid of your disk harrows, or plows. This time of year, spray Roundup and drill grain sorghum, peas, jointvetch, or alyceclover. If no drill is available, spray, wait two weeks, plow and plant. Although the Roundup will kill all germinated plants it contacts, the plowing will likely germinate a new crop of weed seeds (probably reduced in number from the previous crop).

   Poast is a grass selective herbicide that basically kills most grasses but no broadleafs. So, if we are still standing in our food plot in June or July and the plot is a broadleaved perennial like alfalfa, clover, or trefoil being invaded with crabgrass, johnsongrass, bermuda, or fescue, then Poast is our weapon. Even new annual broadleaf plantings of peas, beans, clover, or jointvetch are candidates for Poast which must be mixed with a crop oil concentrate for best results. This is where last year’s planning pays off. If this plot had problems with crabgrass or johnsongrass last year, plow repeatedly and plant a broadleaf. When the noxious grass reemerges, spray with Poast for the knockout punch. Whichever scenario, if the noxious grasses are over six inches tall, mow, wait a week or two, and then spray the regrowth.

   2,4-D is a broadleaf killer that has been around under many brand names for several 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. Atrazine is a great herbicide for grain sorghum or corn, but is a controlled chemical requiring a private pesticide applicator’s license. 2,4-D, Poast, and Roundup are all available over the counter with no license required.

6. Read The Label. This cannot be emphasized enough. Do not apply any more chemical than the label directs! Use at least 20 to 30 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 is a good way to waste money and reduce efficiency. Poast always needs to be mixed with crop oil concentrate, while Roundup and 2,4-D sometimes need to be mixed with surfactants. Read the labels.
7. Timing is Everything. Most weeds are more vulnerable to chemicals when they are young and vigorously growing. Do not spray when plants are wet or when rain is expected within 24-48 hours. Do not spray when it is windy as drift will render spraying ineffective and can be harmful to the applicator. Again, when weed growth exceeds four to six inches, mow, wait one to two weeks and spray regrowth. Do not spray during an extended drought, weed control is ineffective and valuable crop species may be injured or killed.

In summary, chemical herbicides are a safe, effective tool to manage weeds in food plots. Once necessary equipment is obtained, effective chemical applications can be made for $15-$50 per acre. Counting equipment and manpower costs, you cannot plow any cheaper 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 herbicides later as needed for final control. By using chemicals, we have maintained vigorous ladino clover stands for five to ten years without replanting. This is really getting efficient and cost-effective. You, too, can win the weed wars by careful planning and judicious use of chemicals. The results will surprise you. Note: There are hundreds of other herbicides that can be used effectively on deer food plots. The three above were featured because of familiarity, name recognition, low toxicity, easy obtainability. and widespread use. Check with your agriculture extension agent for further information.

Kent Kammermeyer is a Senior Wildlife Biologist with the Georgia Department of Natural Resources, Game Management Section. Kent has over 20 years’ experience working with landowners and hunters to improve the quality of their deer herds and has published 40 scientific and 140 popular articles, most on white-tailed deer.