Six days of waterlogging after silking cut Indiana corn yields 13%

Six days of waterlogging shortly after silking cut corn yields by approximately 13% in published research, and the 2026 season in Indiana delivered far worse: prolonged saturated soils, a 20% solar radiation deficit and floodwaters that submerged developing ears in the worst-hit fields.

The November 4, 2026 assessment of the season documents multiple compounding losses. Waterlogging during the R3 growth stage reduced yields by roughly 16% after eight days and 25% after ten days in prior trials. Excessive rainfall and significant flooding struck several areas of Indiana, raising questions about corn yield, stalk health, grain quality and harvestability.

Corn tolerates flooding during reproductive development better than during early vegetative growth. That tolerance has limits. Extended saturation, prolonged cloudy weather, reduced sunlight and floodwater reaching developing ears together erode crop performance.

Why saturated soil starves the plant

The core problem is oxygen, not water. When soil pore spaces stay filled with water, oxygen availability declines, restricting root respiration, nutrient uptake and overall plant function.

During grain fill, a healthy root system and green leaf canopy are critical for kernel development and dry matter accumulation. Prolonged saturation accelerates leaf senescence, reduces photosynthesis and decreases kernel weight and grain yield.

Flooding also deposits mud and sediment on leaves, further cutting photosynthetic activity. The risk rises sharply when floodwater reaches the ear. Prolonged moisture and sediment inside the husk increase the chance of ear rot and grain quality problems.

How much sunlight did Indiana lose?

From July 31 through August 17, central Indiana received approximately 20% less solar radiation than the previous five-year average. Individual rainy days recorded reductions of 60% to 80%.

Sunlight drives photosynthesis and the carbohydrates that feed kernel development. A few cloudy days cause little damage, but extended low-light periods during grain fill limit kernel dry matter accumulation.

Timing matters. Near pollination and early kernel development, insufficient photosynthesis can trigger kernel abortion. By R3 through R5, kernel number is largely established and yield depends increasingly on final kernel weight. Previous research showed prolonged solar radiation reductions during grain fill cut both kernel weight and final yield.

Stalk cannibalization raises lodging risk

Developing kernels create a strong carbohydrate demand during grain fill. When photosynthesis cannot meet that demand, plants remobilize stored carbohydrates from stalk tissues. This process, stalk cannibalization, weakens stalks and increases lodging susceptibility.

Saturated soils compound the threat by compromising root health and anchorage. Fields that experienced prolonged flooding, reduced sunlight and premature leaf senescence face elevated risk of stalk deterioration and stalk rots — and with it, harvest losses.

Where ear rot appeared, and where it did not

In some of the most severely affected Indiana areas in 2026, floodwaters reached the top of the corn canopy and completely submerged developing ears.

Field observations showed the greatest ear rot incidence and severity occurred where severe August flooding pushed water above the ear. In the same fields, areas where floodwater stayed below the ear generally showed few to no visible ear rot symptoms. The ear line, in effect, marked the disease boundary.

What determines the final loss

The combined effects of late-season flooding, saturated soils and reduced sunlight create multiple challenges for Indiana corn production:

• Prolonged waterlogging restricts root function
• Cloudy conditions reduce photosynthesis and kernel weight
• Weakened stalks increase lodging and harvest losses
• Submerged ears add ear rot, mycotoxin contamination and grain quality risk

Severity depends on flooding duration, crop growth stage, sunlight availability, field drainage and whether developing ears went under. Growers assessing damaged fields should prioritise stalk strength checks ahead of harvest and test grain from flooded ear zones for mycotoxins before storage or sale.