By Blake Jackson
As harvest season nears, University of Missouri Extension specialists report that a flash drought is developing across Missouri, putting crop yields at risk.
According to MU Extension state climatologist Zachary Leasor, the U.S. Drought Monitor released Sept. 4 shows that 93.68% of Missouri is at least abnormally dry following an unusually wet spring. Southeastern and southwestern regions are most affected, while northwestern Missouri remains relatively resilient.
MU Extension soybean specialist Andre Froes de Borja Reis notes that the drought is impacting soybeans during the seed-filling stage, when water demand is highest to transfer nutrients into developing seeds.
“Under dry conditions, soybean seeds may become undersized, resulting in yield loss,” Reis said. He advises growers to anticipate harvest because drought has already limited seed formation in certain areas. “Any rainfall on harvest-matured beans could trigger seed deterioration and price penalties.”
Beans with low moisture content are particularly vulnerable if exposed to rain after reaching harvest maturity. Low test weights are also expected, according to Missouri’s Soybean Growth and Yield Tool.
A similar situation occurred in 2024 when Hurricane Helene brought heavy rainfall, resulting in seed deterioration due to fungi such as Fusarium, Cercospora, and Diaporthe, which can reduce elevator value, explained Mandy Bish, MU Extension state plant pathologist.
MU Extension weed scientist Kevin Bradley warns of potential herbicide carryover, as residual chemicals may not have fully degraded due to dry conditions, possibly harming cover crops planted soon.
Bish also advises monitoring stalk and ear rots, as drought and rapid corn senescence favor fungal pathogens. A simple “push test” pushing 20 plants at a 45-degree angle in multiple areas can assess lodging risk.
Fields with more than 10%-15% weak stalks or visible ear rot should be prioritized for early harvest, since ear rot fungi can continue growing until grain moisture drops below 15%.
Leasor emphasized that no significant rainfall is forecast, and tropical storm relief like last year is unlikely. Preliminary data for August 2025 show this was Missouri’s second-driest August on record, with just 0.79 inches of statewide rainfall.
“This is a classic flash drought, developing rapidly after a wet growing season,” Leasor said, noting that Missouri has experienced 16 drought disasters since the 1980s, each causing damages exceeding $1 billion.
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Categories: Missouri, Crops, Corn, Soybeans, Weather