How to Apply Herbicides in a Cold Snap

emerging corn in a cold snap

Facing a cold snap? Give your young corn plants a few days to recover before spraying your herbicides.

  • Herbicides perform best when ambient temperatures are above 50 degrees.
  • Avoid applying herbicides during a cold snap, when they can’t penetrate the weed’s cuticle.
  • Spraying during a cold snap also increases stress on your corn crop.

It’s early spring and you’re eager to apply your burndown, but then it happens: a cold snap. Suddenly, it feels like winter again.

“Wait until it warms up a couple of days, and then go out and make your application.”

Mike Weber
Principal Scientist, Bayer

You might be tempted to push it and spray anyway, but Bayer Principal Scientist Mike Weber recommends waiting until temperatures climb back up to at least 50 degrees.

“It’s not uncommon for me to get a lot of questions like, ‘If I'm below 40 degrees can I still go out and spray my herbicide? And can that herbicide perform as well as it can at 50 degrees?’” Weber says.

Weber also recommends to retailers and growers “to hold off on that spray until it warms up a couple of days, and then go out and make your application.”

Why a cold snap affects herbicide performance

Chemical weed control is better the higher the ambient temperature is outside – but to a point. (Excessive heat can also hinder herbicide performance). “Cold weather causes weeds to shut down, reducing herbicide uptake through the weed’s stomates – the tiny pores that remain open under warm temperatures – and the waxy cuticle that covers its surface,” Weber says.

“We are able to burn through that cuticle whenever you have warmer temperatures,” he says. “When we have cooler temperatures, those adjuvants are not able to penetrate the cuticle, and therefore the herbicide cannot get into the plant in order to do its job and control that particular targeted weed.”

Spraying during a cold snap increases risk of crop injury

An additional consideration is the stress of the cold snap on your corn crop.

“Anytime you have a really cold snap, the crop is under stress as it is – because it has to battle Mother Nature’s temperature swings,” Weber says.

“Anytime you have a really cold snap, the crop is under stress as it is – because it has to battle Mother Nature’s temperature swings.”

This isn’t the time to add the extra stress of an herbicide application. “Give your corn a few days to recover from the cold snap,” he advises.

For young corn plants that have experienced stress, Corvus® herbicide is a great choice. It even further decreases the chance of crop injury, thanks to built-in safener technology.

“Now Bayer is a very unique company in that we have safeners that are built into Corvus, which actually really enhance and decrease the amount of crop injury that growers would typically see from spraying other products on the market during a cold snap,” Weber said.

CSI™ Safener is a unique technology that aids metabolization of Corvus herbicide in stressed corn plants. The result is a quicker recovery compared to use of an herbicide without a safener.

Applying Corvus herbicide

With over 10 years of proven performance, Corvus (2,27) is the No. 1 pre-emergence corn herbicide.* Growers turn to Corvus to get an early win against weeds for end of season rewards.

  • Application rate: 3.3 to 5.6 fl oz/A
  • Timing: Burndown, pre-plant, pre-plant incorporated, pre-emergence and post-emergence through V2
  • Recommended tankmix options: Atrazine (5), Roundup® Brand Agricultural Herbicide (9), Harness® (15), Dual® (15)

To learn more, contact a Bayer representative.

*Amongst growers – Source: Brand Health Check


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©2019 Bayer Group. Always follow grain marketing and all other stewardship practices and pesticide label instructions. Bayer, the Bayer Cross, Corvus, Harness and Roundup are registered trademarks of Bayer Group. Roundup Ready® 2 Technology contains genes that confer tolerance to glyphosate. Glyphosate will kill crops that are not tolerant to glyphosate. Corvus is a restricted use pesticide. Not all products are registered in all states and may be subject to use restrictions. The distribution, sale, or use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Dual is a registered trademark of Syngenta. For additional product information, please call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at www.CropScience.Bayer.us. Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167.

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