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Missouri expands to D2 drought amid hot spell

Mindy Ward corn plants with rolling leaves indicate signs of stress from drought conditions
DRY HEAT: Later-planted corn is rolling in southern Warren County. Corn in sandy soils desperately needs relief from triple-digit temperatures and could use a shot of significant rain.
Here’s how to manage a stressed corn crop when drought conditions threaten your fields.

Parts of Missouri moved into a D2 drought during the first week in July, while the number of counties in D1 continues to grow.

It has been hot and dry in the Show-Me State. Pat Guinan, University of Missouri Extension state climatologist, says June averaged about 2 degrees above normal temperatures and was dry for parts of central and southern Missouri, where the area received less than 0.50 inches of rain.

Without significant and widespread rainfalls, conditions will continue to quickly deteriorate, he says, especially with extreme heat settling in.

According to the U.S. Drought Monitor’s July 5 map, much of the state — except the northern tier — remains moderately or abnormally dry.

Crop stress is showing

Corn leaves in areas are already rolling, showing signs of stress. As temperatures reached beyond 100 degrees F the first week of July, the little moisture that fell in some areas did not help plant conditions. The earlier leaf rolling occurs in the day, or the longer the time of leaf rolling, the greater the stress the crop is under.

Here is how drought stress affects corn at three stages, according to Iowa State University researchers:

Vegetative. Drought stress during vegetative stages results in shorter plants with less leaf area. When drought stress is combined with heat stress, vegetative development will progress more rapidly. Any stress that occurs during V6 to V8 can result in fewer kernel rows. Stress from V8 to V17 can result in fewer kernels per row.

Pollination. Drought stress seven to 10 days ahead of silking can result in delayed silk development. Drought stress during pollination ultimately results in poor pollination and fewer kernels per ear.

Grain fill. During grain fill, drought stress results in premature death of leaf tissue, shortened grain fill periods, increased lodging, fewer kernels and light kernel weights. Kernel abortion near the ear tip will occur in the two weeks after pollination. Continued drought into the milk stage results in kernel abortion and smaller, lighter kernels. Drought in the mid-to-late grain filling period (milk, dough and dent stages) results in decreased kernel weights and premature physiological maturity.

Managing corn through drought

Famers should make decisions about how to handle the corn crop based on pollination.

If pollination is good, manage the field normally. Where pollination was poor, kernels will likely develop normally, but with reduced yield potential. Farmers may want to consider harvesting poorly pollinated fields for forage or silage harvest.

Missouri drought monitor map

In the event of no pollination, farmers can harvest for possible forage, or leave the crop a cover crop. In the fall, mow or chop.

Here are a few drought resources for farmers:

Report dry conditions

Farmers can submit information to help local, state and national decision-makers assess drought conditions and impacts in Missouri, Guinan says.

You may submit information about conditions in your area to a national survey called Condition Monitoring Observer Reports. Visit go.unl.edu to submit a report.

The survey is for reporting conditions and impacts within the U.S. and its territories. You can directly access the CMOR map at Drought Condition Monitoring Observations and Reports 2022.

“The survey and map will be helpful when it comes to assessing drought conditions and compiling impact reports at the local, county and state level,” Guinan says.

The survey also lets users submit information on extreme conditions and everything in between, from severely dry to severely wet. Input from Missourians helps decision-makers gain a more complete portrayal of drought and flood conditions affecting the Show-Me State, he says.

Contributors can upload image files less than 10 MB in size. “Pictures are extremely helpful,” Guinan says. “When it comes to assessing drought at the local level, a picture is worth a thousand words.”

The University of Missouri and Iowa State University contributed to this article.

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