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Give corn a chance to recover from storm damage

Corn Watch: Foliar injury from hail or wind before the reproductive stage has minimal impact.

Tom J. Bechman

July 18, 2023

3 Min Read
hail damaged cornfield at V10 stage
HAIL DAMAGE: No one likes to see their crop ripped up by hail or wind. Large hailstones hit this cornfield at about the V10, or 10-leaf, stage. However, past data indicates the damage may hurt yield less than you think. Tom J. Bechman

One of the biggest tests of patience in farming is waiting for corn to recover after being hit by hail. Nothing looks worse than a field that was thriving one day and is battered the next.

“If you have a field hit by hail or battered by wind, you need to ask yourself several questions,” says Dave Nanda, director of genetics for Seed Genetics Direct, sponsor of Corn Watch ’23. “Once you answer those questions, check out information used by insurance hail adjusters to determine yield impact on corn from hail.

“Often, damage turns out to be less than you first think, especially earlier in the season. Many factors combine to determine whether storm damage on corn is primarily unsightly and a nuisance, or if it delivers a large yield hit.”

Here are basic questions to consider. They’re not based on the Corn Watch ’23 field, which has escaped wind and hail damage so far this year, but on a field in the same general area.

What does the field look like several days after the storm? It’s going to look worst immediately following the event, Nanda says. Most hail adjusters advise waiting a week before making assessments. That gives plants time to recover. What will grow back becomes clearer.

What stage of growth was the crop in when the storm hit? If the crop hasn’t reached the reproductive stage, damage may look severe, but yield impact may still be insignificant, Nanda says. Damage to leaves during the reproductive stage, when the plant is attempting to feed kernels on an ear, becomes more critical.

Related:Don’t forget about gray leaf spot

What percentage of the total plant was defoliated? How much total leaf mass was lost? Estimating loss of leaf tissue can be difficult, especially when leaves are shredded but still on the plant. Base estimates on the total leaf area of the entire plant, not just what percentage of a few individual leaves are lost.

Are key parts of the plant still intact? Even if a corn plant was at the V10 to V12 stage, if stalks are not bruised and the whorl is still intact, overall damage may be limited. If the tassel inside a V12 whorl is still intact, and leaves aren’t wrapped into a ball, normal development should occur.

How much regrowth can occur? For corn, tattered leaves will remain tattered. However, leaves not yet emerged from the whorl, if the whorl was undamaged, should be normal.

Crop damage assessment

After you’ve answered these questions, you can make an assessment. Use the defoliation chart for corn found in the Purdue University Corn & Soybean Guide. Here are examples:

  • Six-leaf corn, 50% defoliation. 0% expected yield loss; damage estimates start at V7 corn

  • 10-leaf corn, 50% defoliation. 6% expected yield loss, or 12 bushels per acre on 200-bushel yield

  • 12-leaf corn, 50% defoliation. 9% expected yield loss, or 18 bushels

  • 12-leaf corn, 75% defoliation. 16% expected yield loss, or 32 bushels

  • 15-leaf corn, 50% defoliation. 15% expected yield loss, or 30 bushels

  • Tassel, 25% defoliation. 9% expected yield loss, or 18 bushels

  • Tassel, 50% defoliation. 31% expected yield loss, or 62 bushels

  • Blister stage, 50% defoliation. 22% expected yield loss, or 44 bushels

  • Milk stage, 50% defoliation. 18% expected yield loss, or 36 bushels

  • Dent stage, 50% defoliation. 7% expected yield loss, or 154 bushels

Read more about:

Hail Damage

About the Author(s)

Tom J. Bechman

Editor, Indiana Prairie Farmer, Farm Progress

Tom J. Bechman is editor of Indiana Prairie Farmer. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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