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When Weeds Take Over

by Neil Dougherty
Date Posted: 01-01-2010

As a professional wildlife consultant, I know all too well the impact dry conditions can have on wildlife food plots. I spent most of the summer of 2005, like most land managers, watching the ten day future weather forecast hoping for cooler temperature and just a little steady rain. Every day that passed without rain put more pressure on my food plots and gave some of the more persistent weeds a chance to thrive. If your food plots were weedy last year you’re not alone but now its time to decide what to do when weeds take over.

The first step in dealing with a weedy food plot is to determine why the food plot lost the battle with weeds in the first place. Get to the root of the problem, so to speak. Most weed infestations in food plots can be tracked back to a shortcut taken during the original planting process. For example, a food plot will often be overtaken if the soil has not been properly amended.

That’s right, if your soil pH value is too low or you decided to skip applying fertilizer this year you are giving
weeds a huge advantage over the preferred plants in your field. Let’s take for example a food plot that was
planted on a neighbor’s property near my research facility in southern New York. The food plot was planted in an old abandoned hay field. The land manager planted a perennial clover mix in a food plot with a soil pH value of 5.6. Rather than apply granular lime to fix the low soil pH, he decided to try a quick fix and boost the fertilizer rate. Right off the bat the clover mix was in trouble. The low soil pH made it difficult for the plants to absorb nutrients in the soil and resulted in plants that were growing at 45% of their potential. Slow growing clover plants opened the door for weed infestation. In this food plots case, the weed that infested the plot was Ragweed.
Ragweed unlike the clover blend can absorb nutrients just fine when the soil pH is in the low to mid 5’s. In the end it wasn’t even a fair fight, the ragweed dominated the plot by absorbing the limited amount of moisture in the soil and the plot had to be replanted. If you have been working hard on amending your soil and your food plots still are weedy there are other factors that could be at work.

One of the things I run into quite a bit while trouble shooting weedy food plots, is an unnecessary loss of soil moisture during the planting process. I can’t stress enough the importance of managing soil moisture loss within new food plots. There are two very effective ways to manage soil moisture loss. The first technique to conserve soil moisture is to use trees along your plot to block sunlight from reaching the ground and drying the soil.

If you are planting in a part of the country where hot dry conditions are often encountered during the summer growing season, hide your food plot from direct afternoon sunlight. For most of us, the hottest time of the day during the summer months is between 4-6pm. The next time you are in your favorite food plot pull out your compass and look in a southwest direction. That’s where tall trees should be located blocking direct afternoon sunlight from reaching the food plot.

Remember, in the afternoon air temperature has risen and long since burned off the dew. Hot afternoons and direct sunlight will send the soil temperature soaring in fields. High soil temperatures increase the rate of soil moisture loss and give weeds an advantage over preferred food plot plants. Remember, my neighbors plot with the ragweed infestation? His plots also had direct afternoon sunlight and high soil temperatures. Combined hot dry soil with low soil pH and an increased rate of fertilizer and his ragweed grew like it was on steroids.

Another technique that can be used to control soil moisture loss within a new food plot is to be sure to pack a firm seed bed prior to seeding. Using a roller or cultipacker to tighten the seed bed before seeding will not only allow your seed to germinate more effectively but also faster. A well packed soil will quickly absorb and hold rainfall allowing for a better stand establishment in a shorter period of time. More importantly, a well packed seed bed will allow moisture to seep up from deep below the food plot when it’s not raining.

For example, I replanted a food plot in a perennial mix in the spring of 2005 but was running a little late and decided to cut a corner and only cultipack the field once prior to seeding. After I planted the field we had
sporadic rainfall for the next forty-five days. The field looked horrible, only about thirty percent of the seed had germinated. I pushed a soil probe into the soil and found moist soil about three inches below the surface crust.
Moisture was trying to seep to the surface from deep below the plot but the loose soil allowed the moisture to evaporate before it reached the seeds located on the surface of the soil. It was then I knew I had been caught taking a short cut. To fix the problem I cultipacked the failing food plot stand again. Almost immediately seeds started to germinate, soil moisture was seeping from deep within the plot to the surface allowing for faster germination.

Another common factor that contributes to weed infestation is improper care of existing fields. If you have an established stand of Imperial Whitetail Clover or another Whitetail Institute perennial you should be at the very least mechanically controlling weeds by mowing grasses and weeds before they get a chance to reseed themselves within the food plot. In addition to mowing plots, chemicals can easily be used to kill grasses or broad leafed weeds within the plot but sometimes despite technically sound planting practices, effective mowing and grass control techniques, food plots just wear out and become weedy. Chalk it up to Mother Nature not cooperating but some times weeds just take over.

If weeds have taken over your plot you have two obvious choices, kill and replant or chemically treat the plot to remove the problem plants. As a wildlife consultant my first choice when I encounter a weedy field is to save the field without replanting. That means I will use chemicals when possible to clean up the plot. The type of chemicals and rate of application will depend on the type of food plot you intend on treating.

The first step is to identify the type of weed you wish to control. There are lots of recourses available to land managers to help them identify weeds and grasses. Your first choice may be a local soil conservation extension agent or online resources like the Weed Science Society of America (www.wssa.net). The folks at Whitetail Institute have a great track record for helping customers identify weeds by simply calling their help line. Once the problem plants have been identified it’s time to select the type of herbicide to spray over the food plot.  Selecting the right type of herbicide can be a little tricky as some types of herbicides may kill your preferred plants in your food plots as well as the weeds you wanted to control. There are a few rules of thumb that will help you select the right herbicide for your food plot.

Most broadleaf blends of seed can be sprayed with a grass specific herbicide. That means grasses will die but not the preferred food plot plants. For example, you can control grasses in Imperial Whitetail Clover and all Whitetail Institute perennials with a grass-specific herbicide labeled for use on food plots. The forages will not be affected by the herbicide. The folks at Whitetail Institute again revolutionized the food plot business when they introduced herbicides that were specifically designed to be sprayed over their blends. Arrest is the first ever herbicide sold in affordable quantities designed to kill grasses within food plots. Grasses can effectively be wiped out in Imperial Whitetail Clover, Alfa-Rack and Chicory Plus stands. Grasses are not the only type of weeds that can be killed with the proper type of herbicide. Most types of broadleaf weeds can also be eliminated within Imperial Whitetail Clover stands by applying an innovative broadleaf weed killer called Slay. If you have questions on determining the type of herbicide to use on your weedy food plots contact an expert consultant at Whitetail Institute by calling 800-688-3030.

If you have been planting food plots, chances are you have been struggling with controlling weeds and grasses within your fields. My first suggestion is to first back up and try and find out what went wrong within the plot. Be sure not to repeat the same mistake that caused the original weed infestation then solve the problem. The good news, there are products on the market that can dramatically increase the life of your food plot and can clean up when weeds take over.

Reprinted with permission of the Whitetail Institute of North America.
For more info on this article and other related topics contact them at
(800) 688-3030 or visit their website at wwww.whitetailinstitute.com.