Wheat Gets Cold Feet

Be Alert for Winter Flooding Effects on Wheat

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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Wheat that sat under water during last week's floods will survive longer than actively growing summer crops, but damage should still be assessed in the coming months. (DTN photo by Pamela Smith)

ST. LOUIS (DTN) -- What a difference a season makes.

The floodwaters that swamped parts of Missouri and Illinois last week would have covered crops and swept away seedlings in the spring or summer. In late December, however, the biggest agronomic threat to farmers was the winter wheat crop hunkering down for the winter, noted University of Missouri plant scientist Greg Luce.

Fortunately for growers, a dormant, overwintering plant will sustain far less damage from a long swim than a plant that is actively growing in the spring or summer, Luce told DTN. However, some fields have yet to enter full dormancy thanks to the mild temperatures in December, so growers should still make a note of flooded fields and check on their wheat's viability in the coming months, he said.


The December storms were "El Nino-fueled," noted DTN Senior Ag Meteorologist Bryce Anderson. "Rainfall totals reached more than 5 inches in the southern half of Missouri, the southern half of Illinois, and in western Kentucky. Locally-higher amounts covered much of eastern Missouri and southern Illinois, where 8 or more inches of precipitation fell during the Dec. 26-29 time frame alone. And, parts of the St. Louis area took in more than 10 inches during that time frame."

The areas most affected by the flooding -- namely river bottomlands -- aren't prime wheat ground, so the number of wheat acres affected is probably not extensive, Luce said. Moreover, the speed with which the floodwaters rose and then fell means that many wheat plants that were submerged may have come back up for air within a day or two.

During the warm growing months, most crops can't survive underwater beyond four days, and yield loss can begin after just two days. "We don't know exactly how long a plant can survive like that in the winter, but we know it would be longer than that," Luce said.

Plants underwater essentially suffocate; they run out of oxygen, Luce explained.

"When wheat plants are in dormancy, they're not dead; they're still breathing and need oxygen and they use it, but to much less of an extent," he said. "The demand for oxygen is not as great so they're not going to perish as quickly."

Moving water will actually supply plants with more oxygen than still, stagnant pools of water, so rushing floodwaters might have done less damage if the crop stayed in place, Luce added.


Dean Campbell has some alarmingly good-looking wheat on his southern Illinois farmland right now. "It's probably 4 or 5 inches tall and just the prettiest grain -- green as a golf course," he told DTN. "Really, it's too good looking of wheat -- it hasn't gone into dormancy because we haven't gotten too much cold weather yet."

Normally, his wheat has gone dormant by early December, but not this year. The night of Jan. 4 was the first time his fields experienced below-freezing temperatures for the entire night, he said.

Campbell's non-dormant wheat fields escaped the floodwaters, but those that didn't might be at risk for more flood damage, Luce said.

"Even though it's colder and the plant is not growing as rapidly as it would in April, it's using more oxygen than it would if it was dormant," he said of green wheat fields.


If you're worried about the fate of some wheat, you don't have to wait until the spring green-up to assess the damage, Luce said. Growers can dig up wheat plants from the flooded areas and set them inside for a few days.

"Evaluate it for two or three days and see if in the warmer environment it starts to green up and if roots start to develop," he said. "Make sure roots are white and firm. If they are brown or discolored, that's a sign they didn't make it."

This early scouting can cue you into trouble spots, but it will be easier to evaluate entire wheat stands once green-up begins in the early spring. Stands with fewer than 12 to 15 live plants per foot are good candidates for replanting to another spring crop. Thin stands will also benefit from nitrogen applications around Feekes growth stage 4 or 5, Luce added.

For more information on flooded wheat effects and management, see this University of Missouri article by Luce on the topic: bit.ly/1PMqyho

Emily Unglesbee can be reached at emily.unglesbee@dtn.com

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Emily Unglesbee