Early Season Hail Damage

May 30, 2024 2:36 PM
Blog Post

Over the last week, we've seen a lot of active weather across the state. In addition to tornadoes, wind, and heavy rains, areas across the state also got hit with hail. 

Waiting 7-10 days after a hail event helps give the crops a chance to recover and makes it easier to assess the damage. Mark Licht wrote this ICM Blog that goes into more detail on assessing fields with hail damage and if replanting is warranted.

Additionally, below are some reminders and comments for early season hail damage in corn and soybeans:

Corn: The growing point is still below ground until the V6 growth stage. At V6, the growing point is right at the soil surface. While growth stages vary depending upon planting date, the majority of the corn across the state is at or is less than the V6 growth state. While the leaves may look pretty tattered from the hail, that growing point was likely protected below ground or was just at ground level and the corn should grow out of the hail damage.  

Read more on hail damage in corn in the ISU Publication: IPM 78: Hail on Corn.

Soybeans: Soybeans are more vulnerable to hail at this point in the growing season given their growing point is above ground once they emerge. If a soybean plant is cutoff below the cotyledons, that plant is no longer viable. However soybeans not only have a growing point from their apical meristem (uppermost node on the stem), but also by their auxiliary buds, which are located between the cotyledons and the stem, the unifoliate leaves and the stem, and each trifoliate leaves and the stem. If a soybean has only has one or a partial cotyledon, you may be surprised at what those plants will try and do. Regrowth from the auxiliary buds will result in branches that will flower and produce pods and seeds. It typically takes about 4-7 days to see regrowth on soybeans after hail. 

Read more on hail damage in soybean in the ISU publication: IPM 79: Hail on Soybean.

Fungicide-use on hail damaged crops: The other big question related to hail damage is, should one spray a foliar fungicide on hail-damaged crops, especially if it could be added in the tank with a post herbicide application?

A common misconception is that hail-damaged crops will be at a higher risk for disease infection. Note that fungal diseases such as gray leaf spot, northern corn leaf blight and tar spot in corn, or frogeye leaf spot in soybeans, do not require wounding to infect the plant. This is unlike bacterial diseases that often infect the plant through open wounds. However, a fungicide has no effect on bacterial diseases.

Another reason some consider spraying a fungicide post-hail relates to the physiological benefits and trying to protect the yield potential of the hail-damaged crop

ISU has done some research looking at if a fungicide provides any yield-increasing benefits after an early-season hail event, and the quick and short answer is no. Read more in this ICM blog.

Finally, if you have hail damage, make sure you are in communication with your crop insurance agent


Rebecca Vittetoe Field Agronomist in EC Iowa

Rebecca Vittetoe is an extension field agronomist in east central Iowa. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors.

Areas of expertise include agronomy, field crop production and management of corn, soybeans, and...

Terry Basol Field Agronomist in NC Iowa

Terry Basol is an agronomist in north central Iowa and field specialist for Iowa State University Extension and Outreach.