Agronomic Review of Derecho Damage

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By Brian Berns and Kevin Fitzpatrick

This large thunderstorm cell stretched 770 miles across the Midwest packing rain, hail, and sustained winds that reached over 100 MPH in many areas across Iowa.

This derecho left severe crop damage in its wake. Corn damage can be categorized three ways; twisted, snapped, and root lodged and flat.

Location map Derecho 2020 vf
Landus' locations in the path of the storm; damage from Churdan through to Bondurant

Twisted: Caused by down drafts from the storm, corn looks very uneven, but the entire field is not lying flat. In most cases this will continue to stay twisted in spots and you will find out the impact at harvest based on the percentage of damage. Today, that could range from 10-40% of stalk damage but still has the ability to yield.

Root-lodged and Flat: Whether laying flat or roots which have come out of the ground, this corn will continue to move forward but we are not elongating cells anymore, so the plant will continue to try to push itself up with leaves, but with no growth, you will see very little goose neck in the fields.

These is a wide range of impacts on yield and it is too early to tell today what that might look like. Iowa State University says there could be a wide range of 12-31% yield impact after root lodging on corn after V17 which is 1 to 3 leaves before tassel.

Snapped: We have also found plants that have snapped off, mostly at spots where there was Physoderma brown spot around the nodes of the plant. Where these plants are snapped, it will be very difficult to harvest these fields without corn reels, and going one direction with the combine.

Today these are the three areas we are looking at, we have seen multiple areas where it was driven by hybrid, and areas where the wind was so forceful that not much survived.

We are still evaluating the damage day by day. We saw big differences in impact just 24 hours after the storm so we will continue to help you assess.