6 Tips for In-season Corn Weed Scouting

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Scouting corn field for weeds

As a corn farmer, you know regular scouting is an important part of your overall weed control strategy. However, you also know how easy it can sometimes be to let the days — or weeks — slip by as your time gets taken up by other work. With in-crop applications winding down, now is the perfect time to focus on getting in the habit of consistent scouting.

Here are six tips to help you make the most of your weed scouting efforts this growing season:

  1. Create a scouting kit. Before you head into the field, put together a kit of a few items that will make scouting easier. Keeping everything together in a bag, in an easy-to-remember place, will make the task just a little quicker. Here are suggestions for items to put in the kit:
    • A notebook or tablet
    • Plastic bags for plant samples
    • Markers to label sample bags
    • Magnifying glass/hand lens
    • Camera or mobile phone for taking photos
    • Field guide (hard copy or mobile application)
    • Small shovel for digging up plants
  2. Make several stops. Make at least one or two stops per 20 acres of cornfield to look for weeds.
  3. Note weeds present. Take note of which weeds are present, how severe the populations are (roughly how many of each species) and which growth stage the weeds are at. You can refer to this timeline to see when common species typically emerge in Midwestern cornfields.
  4. Watch for resistance. You’ll want to watch out for resistance. If you’re noticing the same weeds escaping the chemistries you’re using while other weeds are under control, resistance could be the issue. If you suspect herbicide resistance, it’s a good idea to take a sample of the weed and send it to your state diagnostic lab. Typically, labs will ask for you to collect seeds from mature plants at harvest and send them in for herbicide resistance testing. However, you’ll want to check with the lab ahead of time to find the proper steps to follow.
  5. Take good notes. Take notes and keep them for future reference. Record the weeds you find, the time you scout, the location, the weather and any other details you think are important. Keep these notes for future reference to help inform plans to control them next season and beyond.
  6. Make it a habit. Scout often, at least every two weeks. Once a week is even better if you have the time. Some weeds can grow very quickly and will limit yield if they get out of control early in the season. Palmer amaranth, for example, can grow at the rate of 2 to 3 inches per day, eventually reaching up to 8 feet tall. If Palmer amaranth is left to flourish among young corn, it can severely diminish yield. Timely scouting will allow for easier control of those weeds.

Although weeds are the focus of this article, don’t forget to watch for other threats to your corn yield while you scout, including diseases and insects. And, during harvest, be sure to use your time in the combine to your advantage to watch for escaped weed populations from your view above the mature corn.

Later on, as you gather all your notes from this year and start planning your weed control program for next season, be sure to consider the corn herbicides from Corteva Agriscience. We have powerful, flexible solutions to fit the way you farm.