The Eastern Corn Belt is set to get hit with a blast of cold air which will put our overnight temperatures in the mid-30s or below. That kind of freeze event could cause some serious damage to your wheat, soybeans and corn.
Christopher Bauer, Pioneer agronomist, says that wheat acres are approaching the jointing phase. That’s when growing point is above the soil surface, making it vulnerable to frost.
“You need 24 degree temperatures for a couple hours for injury to occur,” he said. “If it does get that low, and you want to see if any injury occurred, I would wait about seven to 10 days to make any assessments as it takes time for any definitive signs to show up in the plant.”
After that time frame has passed, Bauer says growers should split the main stem of the wheat down the middle to look at the growing point.
“You’ll see the developing grain head—just above the uppermost node-that growing point is a lightish green in appearance and turgid-looking, than you wheat is healthy,” said Bauer. “If that growing plant has been damaged, it’ll lose its greenish color and look off-white or slightly brownish
In soybeans, 32 degrees can cause frost damage to emerged beans. On lighter-textured soils, if temperatures reach below 28 degrees, it could be lethal.
“A soybean plant at the cotyledon stage has three growing points,” said Bauer. “Recovery from a freezing injury is possible as long as at least one of those buds survive. Soybean seedlings that have just cracked the soil surface, those will be more tolerant to freezing temperatures.”
If you suspect your soybeans have frost damage, Bauer says the symptoms should show up in about five days.
As for corn, if much has emerged this week, Bauer says frost risk is pretty small as long as the growing point is below the soil line.
“The growing point doesn’t emerge above the soil surface until around V5, V 6, so corn should be pretty safe,” he said.
You can check for frost damage in corn roughly three to five days after the frost.