How to Spray Roundup Ready Corn

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Things You'll Need

  • Soil-applied residual herbicide

  • Roundup

Roundup Ready® corn is corn that is genetically modified to be resistant to applications of glycophosphate, or Roundup. Roundup Ready corn allows farmers to spray for weeds without fear of harming their crops. Weed treatment is still necessary when growing Roundup Ready corn, so understanding the proper protocol is essential to bringing a good crop to harvest.


Step 1

Use a soil-applied residual herbicide at the beginning of each growing season. Many farmers skip this step once they switch to Roundup ready corn, thinking that post-emergence applications of Roundup will be sufficient. But Roundup is most effective on weeds that are four inches tall, and in the time between germination and four inch height weeds can siphon off nutrients from the soil that are vital for high crop yields. You can apply the residual herbicide at half strength, but don't skip this step.


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Step 2

Perform the first post-emergence application of Roundup when weeds reach three to four inches in height. The soil-applied residual herbicide should limit the presence of those weeds that are able to grow, but cannot be relied upon to completely eliminate the entire weed population.

Step 3

Scout your fields two to three weeks after the first post-emergence application of Roundup. If you see newly germinated weeds, follow with a second post-emergence application.


Step 4

Follow this protocol every year. Roundup Ready corn allows farmers to control for weeds early in the season before they set seed. This, in turn, reduces the overall presence of weeds in the first place, which means lower overall costs for weed control. There won't be any way to completely eradicate weeds in your fields, but early treatments will keep weed seeds from having a safe place in your soil.



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