Weather patterns for corn production are shifting throughout the United States. The midwestern and eastern United States are experiencing increases in total precipitation as well as in heavy precipitation events (Wilson, et al., 2022; Wilson, et al., 2023; Jay, et al., 2023), indicating more frequent and intense storms than experienced in the past.
As shown in Figure 1, more frequent precipitation has reduced the number of days suitable for fieldwork in April and May (KSU, n.d.). Management decisions to lessen the negative yield impacts from short-term severe weather events could involve decisions prior to their occurrence (e.g., planting date, hybrid selection), as well as responses after occurrence (e.g., fertilizer management, remedial product applications, crop termination decisions, shifting the targeted crop market channel). This fact sheet highlights current knowledge regarding corn response to four short-term or acute weather stressors (Lindsey, et al., 2024):
- cold temperatures (associated with cold fronts)
- flooding or waterlogging
- damage from hail events
- wind damage causing stalk breakage or lodging
1. Cold Temperatures (Early-Season and Late-Season)
Damage to corn crops associated with cold fronts is typically most concerning during the early season (prior to or shortly after emergence) or during late-season grain fill. Prior to emergence, damage to corn is likely to stem from imbibitional chilling (within the first 24 hours of germination process) or from cold injury to seedlings (after imbibition is complete but prior to emergence).
Corn seeds are relatively tolerant to cold-water uptake above 39 degrees Fahrenheit, but cold injury to mesocotyls and emerging plants can occur at temperatures below 46 F. Colder soil temperatures also result in more calendar days needed for emergence as early-season emergence is controlled by soil-accumulated growing degree days (GDDs). Approximately 180 GDDs are needed to achieve 90% emergence.
To manage for cold prior to emergence, consider planting as soon as soil temperatures are predicted to remain at or above 46 F. Also, consider testing seed lots for vigor prior to planting—higher vigor scores should result in better emergence under cold stress. If stand loss is severe, consider replanting after evaluating the actual crop stands, weather forecasts, and time of the year. Be aware that a lower crop stand planted earlier can result in a yield comparable to a higher crop stand planted later.
If cold temperatures cause plant injury but do not kill the plant after emergence, minimal management practices are recommended. No action may be warranted if up to 70% damage to leaves occurs at the vegetative growth stage 4 (V4). Farmers will still want to assess fields with this level of damage over time as delays in canopy closure and flowering may result from early-season tissue injury and may affect weed control strategies or timing of a fungicide application later in the season.
Early frosts in the fall could also be a concern if they are severe enough to damage leaf tissue or prematurely end the grain fill period. Yield losses of 6%–40% were incurred if the seed moisture content was between 35%–55% when the crop was frost-killed. Premature seed death decreases viability and vigor and results in low test weights and greater kernel damage, affecting grain quality and marketability. Management recommendations to address different forms of cold injury during early or later growth stages are shown in Table 1.
2. Excess Water (Waterlogged and/or Flooded)
Injury to corn from waterlogging and flooding is more severe early in the season and lessens as the crop develops. Waterlogging happens when only the root system experiences saturated water conditions due to excess water, causing anaerobic/low oxygen conditions. Flooding occurs during partial and/or complete submergence of plants in standing water (below ground and above ground).
The survival of plants under flood water prior to emergence is largely dependent on soil temperatures. If soil temperatures are cooler (60 F), survival from waterlogging for up to 96 hours (about four days) is good, with 70%–80% emergence possible. Warmer temperatures (80 F) are more damaging, lowering emergence from 90% to 60% after 48 hours. After 96 hours, 10%–30% emergence is experienced. Warm soil temperatures during flooding early in the season will likely warrant replanting. If cooler temperatures occur before emergence during flooding, shallow surface tillage may be required to remove the surface crust likely to form as the standing water recedes. Evaluate emergence after the waterlogging conditions resolve before making this decision.
After emergence, 96 hours of flooding or less during the early vegetative stages results in yield losses that typically range from 20% to 30%.
While crop injury can occur as a result of flooding, losses of applied nitrogen (N) can also compound yield losses. Consider waiting to side-dress N in fields prone to flooding until the vegetative growth stage 6 (V6). This can reduce N losses and ensure that an adequate supply of N is present in the soil for the crop after the V6 growth stage.
Yield losses are substantially less as the plants enter reproductive stages (0%–20% yield loss from eight days of flooding). Concerns for flooding later in the season relate to the induction of premature grain sprouting (if ears are submerged), as well as contamination of silage or grain due to soil particles deposited on plants. If possible, overhead irrigation can help remove the soil particles deposited on plants due to receding floodwater. For more details on managing for excess water conditions, please refer to Table 1.
3. Hail Damage (Early, Mid, and Late-Season Damage)
Hail and wind damage can occur with strong storms and tend to be more damaging later in the growing season. Consider two factors when addressing hailstorm damage to crops:
- hail characteristics (e.g., size, number, speed)
- target characteristics (e.g., crop, stage, hybrid)
Damage to corn crop from hailstorms can lead to a reduction of plant stands early in the season and during vegetative stages; leaf defoliation and stalk damage during midseason, vegetative, and reproductive stages; and damage to ears, stalks, and grain quality late in the season and during reproductive stages. Yield loss to hail-damaged fields varies based on intensity (more damage corresponds to greater losses) and stage (losses increase during pollination and early seed set). Current management strategies include varying planting dates, planting hybrids that develop and mature at different times to vary the flowering date, and obtaining crop insurance policies for hail protection.
Ohio-specific data from research trials where hail damage was simulated in corn can be found in Ohioline fact sheet AC-1054 Corn Yield Response to Damage from Strong Storms (Lindsey & Thomison, 2022). Current research on corn loss due to actual hail damage is limited. Many studies focus solely on defoliating the plants rather than creating plant damage similar to the damage from naturally occurring hail events, which could include stem breakage, bruising, or damage to the whorls.
When hail damage happens early in the season and is considered severe, replanting corn or other shorter-season crops is an option. Accurate assessments at least one week after the storm and consulting with the crop insurance agent and an agronomist are recommended. Additionally, foliar fungicides at the tassel stage (VT) or later can help protect against disease if pressure is high, but the effect is minimal when disease pressure is low. When hail damage exists and corn is used for feed, some livestock species may be more tolerant to poorer grain quality issues than others. Also, harvesting corn as silage earlier in the season can avoid further disease development and preserve quality.
4. Wind Damage (Lodging and Stalk Breakage)
Floppy corn early in the season can be a result of planting during weather extremes that cause hot dry soil or compacted wet soil. These conditions can restrict or limit early root growth in corn. Plants may appear healthy but could lodge following a rain or wind event. Lodged plants may recover and exhibit goosenecking/bent stalks, but other damaged plants may not recover, leading to yield losses as result of a reduced stand. To guard against yield losses due to lodging and stalk breakage, assess stand losses and consider replanting if the time needed to increase the crop stands will result in yield gains despite the delayed planting date.
Yield losses from root lodging where the stem remains intact are most severe (up to 45% yield loss) when they occur during pollination. However, corn that becomes root lodged during grain fill stages may be non-harvestable, resulting in up to 100% loss if the damage is severe and no harvest accommodation is available. Susceptibility to root lodging rises due to more plant competition when seeding rates are increased. Lodged corn that experiences stalk breakage after crop maturity can result in 5%–25% yield losses. These effects may warrant election of a different crop insurance category to cover potential losses rather than insurance used for hail or wind damage.
Regardless of the lodging type, ears will be closer to the soil surface and canopies may become restrictive for airflow. These issues leads to lower grain quality and can result in ears more prone to development of diseases. To lessen these issues, farmers may consider application of a fungicide at flowering or after flowering if potential diseases are anticipated. Green snap (stalk breakage) typically occurs in later vegetative stages, but is also possible during reproductive stages, resulting in breakage above the ear or below the ear prior to harvest, which can result in major yield losses. Unlike root lodging, seeding rate increases did not affect the occurrence of green snap, suggesting that damage corresponds more to genetic or crop stage susceptibility when storms occur. Reported yield losses due to green snap also suggest that more yield losses occur at seeding rates lower than 36,000 plants per acre.
Management of Stressors: Summary
Corn response to short-term or acute weather stressors (cold, flooding or waterlogging, hail damage, wind damage) is highly variable and can affect corn crop and yields drastically. Varying planting dates to vary the growth stage of hybrids when they experience severe weather and planting hybrids with different characteristics (e.g., leaf number, relative maturity, plant height) are among the agronomic practices that can help lessen the amount of crop loss incurred during short-term severe weather events. Spreading out the flowering and harvest windows over time is a management decision that can help minimize risk, but it requires greater management and recordkeeping and can incur some yield penalties (e.g., delayed planting could result in lower yields if the season is free of severe weather). A list of potential management options to help control damage from severe storms and short-term weather stressors has been assembled in Table 1.
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Additionally, crop damage and losses can result from long-term weather patterns (drought/heat, low solar radiation quality, limited heat unit accumulation). These factors and management recommendations are summarized in Ohioline fact sheet ANR-0150 Corn Response to Long-Term Weather Stressors (Ortez, et al., 2024).
Additional Resources
Video abstract for the Lindsey, et al. (2024) article published in Crop Science:
youtube.com/watch?v=awe4JVU69hc
References
Jay, A. K., Crimmins, A. R., Avery, C. W., Dahl, T. A., Dodder, R. S., Hamlington, B. D., Lustig, A., Marvel, K., Méndez-Lazaro, P. A., Osler, M. S., Terando, A., Weeks, E. S., & Zycherman, A. (2023). The fifth national climate assessment [Webpage]. Retrieved March 25, 2024, from
doi.org/10.7930/NCA5.2023
Kansas State University. (n.d.). K-State fieldwork capacity tool [Webpage]. Retrieved March 25, 2024, from
agmanager.info/farm-management/machinery/days-suitable-fieldwork-all-states
Lindsey, A. J., Ortez, O. A., Thomison, P. R., Carter, P. R., Coulter, J. A., Roth, G. W., Carrijo, D. R., Quinn, D. J., & Licht, M. A. (2024). Severe storm damage and short-term weather stresses on corn: A review. Crop Science, Early View.
doi.org/10.1002/csc2.21212
Lindsey, A., & Thomison, P. (2022). Corn yield response to damage from strong storms [Fact sheet]. Ohioline.
ohioline.osu.edu/factsheet/ac-1054
Ortez, O., Lindsey, A., & Wilson, A. (2024). Corn response to long-term weather stressors [Fact sheet]. Ohioline.
ohioline.osu.edu/factsheet/anr-0150
Wilson, A. B., Avila-Diaz, A., Oliveira, L. F., Zuluaga, C. F., & Mark, B. (2022). Climate extremes and their impacts on agriculture across the eastern corn belt region of the U.S. Weather and Climate Extremes, 37.
doi.org/10.1016/j.wace.2022.100467
Wilson, A. B., Baker, J. M., Ainsworth, E. A., Andresen, J., Austin, J. A., Dukes, J. S., Gibbons, E., Hoppe, B. O., LeDee, O. E., Noel, J., Roop, H. A., Smith, S. A., Todey, D. P., Wolf, R., & Wood, J. D. (2023). Fifth national climate assessment, 24. Midwest [Webpage]. Retrieved March 25, 2024, from
doi.org/10.7930/NCA5.2023.CH24