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U.S. Drought Monitor map for Missouri released Sept. 4, 2025.
COLUMBIA, Mo. – As harvest nears, University of Missouri Extension agronomy specialists see signs of flash drought creeping into Missouri farmland and threatening crop yields.
According to MU Extension state climatologist Zachary Leasor, the U.S. Drought Monitor map for Missouri released on Sept. 4 shows that 93.68% of Missouri is at least abnormally dry following an unusually wet spring.
The southeastern and southwestern parts of Missouri are hardest hit, but the rest of the state except for northwestern Missouri is showing emerging signs of drought.
Soybean specialist: Anticipate harvest
The rain shortfall comes just as most soybean are in the seed-filling stage, when demand for water is highest to produce and transfer photoassimilates into seed reserves, says MU Extension state soybean farming systems specialist Andre Froes de Borja Reis.
“Under dry conditions, soybean seeds may become undersized, resulting in yield loss,” Reis says.
Related story: MU Soybean monitoring report predicts sharp decline in yield
He recommends that growers consider anticipating harvest. “Drought has already reduced seed formation in some regions and planting date scenarios, and any rainfall on harvest-matured beans could trigger seed deterioration and price penalties,” he says.
Undersized and overdried beans are particularly vulnerable to deterioration if rainfall there’s rain after harvest maturity. Beans with low moisture content become especially prone to damage following rainfall, says Reis.
Low test weights are already expected due to drought during the seed filling, as predicted by the University of Missouri’s Soybean Growth and Yield Tool.
Something similar happened in the 2024 growing season when Hurricane Helene brought heavy rainfall to southern Missouri in late September, exposing mature beans to excessive moisture.
However, seed deterioration and other quality issues only became apparent after the storm. Deteriorated seed from the 2024 storm was tested and found to contain species of Fusarium, Cercospora and Diaporthe, which can lead to dockage at the elevator, says Mandy Bish, MU Extension state plant pathologist. Learn more from the MU Integrated Pest Management article “Soybean Seed Deterioration in Southern Missouri.”
Reis notes that the Soybean Farming Systems Yield Prediction Tool currently forecasts a yield decrease in several areas. More details are available at MU Extension Soybean Growth Monitoring.
Weed scientist: Watch for herbicide carryover
MU Extension weed scientist Kevin Bradley says growers should watch for herbicide carryover to cover crops that will be seeded or planted soon. Residual herbicides applied later than usual in corn or soybean this year may not have fully degraded because of dry conditions at the end of the season. This creates the potential for injury of cover crops species planted in the coming weeks, says Bradley.
Disease and drought
“With rapid corn senescence and drought conditions, farmers should scout for stalk and ear rots, as some fungal pathogens favor these stresses,” says Bish.
The “push test” is a simple way to assess lodging risk: Push 20 plants in five areas of a field about 45 degrees. A weak stalk will snap or break, while a strong one will remain intact.
Bish advises prioritizing early harvest for fields where more than 10%-15% of stalks are weak or where noticeable ear rot is present, as many ear rot fungi continue to grow until grain moisture falls below 15%.
Find more information in “An Overview of Ear Rots” from the Crop Protection Network.
No immediate relief in sight
Leasor says no significant rainfall is forecast, and tropical storm relief like last year is unlikely.
Preliminary data for August 2025 indicated this was Missouri’s second-driest August on record, with just 0.79 inches of statewide average precipitation. Springfield saw its driest August ever with only 0.19 inches, and Columbia recorded 0.11 inches, its second driest.
“This is a classic flash drought, developing rapidly after a wet growing season,” Leasor says.
Since the 1980s, Missouri has experienced 16 drought disasters costing $1 billion or more each in damages, underscoring the need for proactive management, he says.