You can’t predict exactly when yield-robbing weather events will occur, but it helps to know when your crop is most at risk and what to look for to calculate yield loss if your crop incurs damage from frost, flood, hail, wind or drought.
Frost damage to soybeans
Soybeans are most susceptible to frost damage during April and October. The severity of frost damage depends on how low the temperatures drop, how long freezing temperatures last and the soybean growth stage. A few hours at or below 30 F can be long enough to kill soybean tissue and impact yield.
Soybean plants with green pods (R6) are most affected by frost. Green beans cause harvest issues and incur dockages at the elevator. More mature plants can withstand frost better, especially if one or two pods on any of the upper four nodes have turned completely brown and the others are yellowish tan (R7).
Yield impact of frost damage in soybeans
Some plants can recover from frost, so wait a week before scouting for frost damage to get an accurate assessment of yield potential.
Spring freeze damage symptoms
Symptoms include:
- Water-soaked lesions on cotyledons, leaves or hypocotyl that dry and turn brown, usually within seven days
- Discolored hypocotyl
- Brown leaves and wilting (for later growth stage soybeans)
Fall freeze damage symptoms
Symptoms include:
- Shriveled, discolored leaves
- Grain discoloration (green indicates damage)
- Delayed soybean maturity and dry down
- Abnormal filling of small pods on the upper part of the plants
- Pod abortion
- Increase shatter risk
Excessive rain and flooding impacts on soybean
Soybeans are most at risk for experiencing damage from flooding between May and June. Yield loss is most severe when flooding occurs during the reproductive phases of growth.
Symptoms found in a flooded soybean field can include:
- Reduced germination rate (in early-season floods)
- Yellowing of foliage (due to poor N fixation)
- Increased risk of disease
- Lodging
- Increased pod shattering (in late-season floods)
Yield impact of flood damage in soybeans
Flooding doesn’t always kill soybeans plants outright, but indirect effects of a flooded soybean field can significantly impact yield.
Flood damage severity is typically based on the following:
- Growth stage when flooding occurs
- Duration of flooding
- Temperature during flooding
- Soil type and field drying capabilities
You can reduce flood damage with proper management.
Wind and hail damage in soybeans
Wind and hail damage are most likely to occur in June through September.
Symptoms of hail damage in soybeans include:
- Leaf defoliation
- Stem damage
- Pod damage
- Stand reduction
- Increased susceptibility to stem rots and disease
- Reduced oil and protein content
Scout seven to 10 days after the event to obtain an accurate estimate of stand loss and leaf defoliation.
Yield impact of hail damage in soybeans
Yield loss due to hail varies at different soybean growth stages. Calculating potential yield loss from hail must account for the percentage of leaf area destroyed (including leaves lost because of broken or cut-off nodes).
Soybeans at R1 withstand hail defoliation better than R3, R4, and R5 soybeans. With up to 50% loss of leaves at R1, yield was still ~95% of maximum potential. But with 50% leaf loss at R3, R4, or R5, only ~80% of yield potential was reached, dropping to ~60% of yield potential when 75% leaf loss occurred at R3, R4, or R5.¹
Late-season hail events especially can result in significant yield loss. Wind damage in soybeans is uncommon but can occur if plants are already weakened.
Soybean drought stress
Most common in July and August, drought stress can pose severe challenges to soybean crops. Especially during the reproductive stages of soybean growth, if water supply is limited, yield potential can fall significantly.
Symptoms of heat and drought stress in soybeans include:
- Stunted vegetative growth
- Leaf flipping (leaves flip upside down, exposing their silvery undersides)
- Leaf curling or clamping
Scouting for these symptoms can help you determine how best to manage soybean drought stress.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent or a seed company professional like your regional BASF representative.
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Endnotes
- Soybean Recovery After Leaf Defoliation.” Purdue University, 4 May 2026, extension.entm.purdue.edu/newsletters/pestandcrop/article/soybean-recovery-after-leaf-defoliation/. Accessed 23 June 2026.
