Soybean damage and replanting

Soybean injury occurs somewhere in Minnesota every year, usually due to hail.

Here, you’ll find guidance on how to evaluate crop damage, make stand counts, assess regrowth potential and decide whether to replant.

Recovery basics: Understanding soybean injuries, growth and regrowth

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Replanting considerations

How damaged soybean plants regrow

A soybean plant will usually regrow when the main stem gets cut off due to insect feeding, hail, sand blasting or other causes.

After a main stem has been cut, one or more axillary buds may develop. One usually becomes dominant because it develops to a greater degree than other branches. Later, it can easily be mistaken for the original main stem, unless you carefully inspect the lower plant section to locate the cut-off point.

Plants cut off below the cotyledons will not recover. In any plant stand evaluation, count these plants as dead. While some hail-damaged plants that look like they should recover eventually die, most regrow from either one or both of the axillary buds located at the node below where they were cut off.

Main stem cut above the cotyledons

Plants cut above the cotyledonary node will re-grow if there’s sufficient cotyledon tissue to provide the plant with energy to regrow.

If the plant doesn’t have sufficient cotyledon tissue left to sustain the plant, count this plant as dead. Plants with all of one and part of the other cotyledon, and should regrow.

The amount of remaining cotyledonary tissue influences the regrowth rate.

Main stem cut above the unifoliolate node

Plants cut off above the unifoliolate node can regrow from any of the four axillary buds located in axils at the cotyledonary node and the unifoliolate leaf node. However, they’re most likely to regrow from one or both of the upper buds at the unifoliolate node.

Green leaf tissue is the key to generating regrowth. Even if unifoliolate leaves are shredded and torn, the remaining green tissue can still generate regrowth. You should see this regrowth within three to four days if growing conditions are favorable.

Bruised stems

In addition to shredding and cutting stems, hail may bruise plant stems. Bruises usually occur on the stem’s lower portion. Intensity ranges from a mild bruise, which is a simple break in the outer stem tissue, to a severe bruise, which exposes the central stem tissue.

Plants with bruised stems that recover after a hailstorm may break at any point before harvest. Such broken-over (lodged) plants usually produce pods and seed. However, because they lie on the ground, harvesting them may not be possible.

Bruised plants that don’t break over don’t affect yield. The challenge is accurately determining which plants will break over at a later date, and which plants sustained only slight bruising. Unfortunately, it’s nearly impossible to determine this shortly after hail damage.

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Making the replant decision

Using the information on plant population and late planting, compare the estimated losses from the crop damage with the yield potential and costs associated with replanting the crop.

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Dale R. Hicks, emeritus Extension agronomist and Seth L. Naeve, Extension agronomist

Reviewed in 2018

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