Hail Damage to Late Vegetative to Silking Corn and Options

By Jenny Rees and Justin McMechan et.al

Several severe hailstorms have hit portions of Nebraska in the past month. The timing of the storms, development stage of the crop, individual field damage, subsoil moisture and crop insurance are important factors in decision-making.

Much of the corn in Nebraska prior to hailstorms the past two weeks was in the late vegetative stages through silking stages of development. Damage assessment in the late vegetative stages is based on leaf loss and stand reduction.

To determine yield losses due to defoliation, you’ll need to determine the stage of the plant at the time of the hail event. Defoliation should be estimated based on missing leaf area and tissue that is no longer green. Assess defoliation on plants at three places in the field to get an accurate estimate. To estimate yield losses based on these defoliation averages, see Table III of the EC126 Evaluating Hail Damage to Corn. It indicates corn at the 13^th leaf stage with 50% defoliation could have a production loss of 10%; 100% defoliation would lead to a 34% loss in production. Complete yield losses can occur if all leaf area is destroyed in corn at the VT (tassel stage).

Yield losses from plant stand reductions are still accounted for in corn through the 17^th leaf stage. It’s important to note that the Corn Loss Adjustment Standards Handbook has two tables — one for corn prior to 10^th leaf and another from the 11^th to 17^th leaf stage.

Depending on the hail damage and how close the plant was to tassels shooting and silking, you may observe hailstone bruising to tassels and ears. You can pull out a few whorls and carefully unroll the leaves around the tassels to assess this. You can also pull the primary ear shoot and carefully unroll the husk to assess bruising to the ears. From experience, bruising on the ears leads to grain molds developing in those areas (fungicides will not help with this). Also watch for timing of pollen shed vs. silking and any impacts to resulting pollination. Be aware that hailstone bruising to the stem can allow for stalk rot to set in. Fungicide can help with stalk strength.

Options with Additional Considerations

These options are dependent upon the corn development stage prior to hail damage and resulting damage after hail. They’re also dependent on soil moisture as parts of Nebraska are seriously short on subsoil moisture. Perhaps the biggest concern is weed control with these open canopies as tiny waterhemp/Palmer are already emerging in these hail-damaged fields.

1. Leave it alone if the corn had mostly stripped-up leaves and new growth is occurring in the whorl (Figure 2a). For those with a large portion of stalks with tassels above the ear removed in the field, yet there’s also tassels that remain in the field, you may also need to leave the field or at least strips for crop insurance final decisions at harvest.
2. Replant corn: The field must be released by crop insurance. Because it’s past June 14, the corn crop would not be insured by federal crop insurance. We haven’t heard many choosing this option approaching July 15. Using the U2U model can help you assess the probability of different hybrid maturities making it to physiological maturity before the average frost for your area of the State.
3. Plant soybean: For those with only stem bases remaining (Figure 2b), some have considered planting soybeans (either by directly planting/drilling the soybean remaining residue or shredding then drilling/planting beans). The field must be released by crop insurance. Considerations here include seed cost for at least 150,000 seeds/ac, seeding cost, seed treatment fungicide cost and herbicide cost. One also needs to consider any replant restrictions for the corn herbicide used in 2023; one assumes the risk if planting soybeans prior to this interval. We also recommend at least a 0.5-unit reduction in maturity group for better probability of reaching physiological maturity prior to a killing frost. Please see Hail Damage to Soybeans in the Reproductive Stages and Options for more information.
4. Plant a forage crop: For those with only stem bases remaining and with short forage due to drought, many are considering a forage crop. For this option, the field must be released by crop insurance. It is important to check if there are any replant restrictions for seeding a particular cover crop. If one chooses to seed a cover crop before the replant restriction listed on the label, the risk is on that individual for cover crop germination and growth. Opportunities exist for warm-season annual forages planted in July or warm-/cool-season forages planted in August. The following BeefWatch article shares annual forage options for July or August plantings. The following forage options after hail damage to crops video shares additional information.
5. Graze the corn: For the fields where the stalks were mowed off at the ear or lower (Figure 2c), and for those needing forage, some have considered grazing the cornstalks. In talking with producers, some want to graze the stalks first and then plant a cool-season forage this fall after grazing. Others are planning to fly in turnips/radishes to graze with the cornstalks. The corn must be released by crop insurance to consider grazing. One also needs to consider any grazing restrictions from chemicals applied to the corn crop. If choosing to seed a cover crop, consider any replant restrictions; the risk is yours if you plant before that interval is up. Regarding nitrates, we consider this situation similar to cattle grazing drought-stressed corn prior to ear development. Nitrates most likely will be present. For best practices, do not turn the cattle into cornstalks empty — have a source of fresh water, and allow them to openly graze the field. Consider supplementation of hay/energy. It is important to avoid grazing the lower eight inches of the stalk.