Friday, November 1, 2013

Freeze Damage to Soybeans and Harvest Options

Chad Lee, Extension Agronomist, University of Kentucky

Freeze Damaged Soybeans. Image courtesy of Curt Judy
The freezing temperatures wilted leaves and killed soybeans in some fields across Kentucky. Now that temperatures have warmed up again, we can better determine how to manage the crop from here.

The vast majority of soybeans were done growing and seeds were in the process of drying down. Those plants were at full maturity where the leaves had dropped, the pods were brown or tan and the seeds were yellow instead of green. Seed moisture was less than 20%. For those soybeans, the freeze events delayed drydown a little but did not harm the plants or the yield.

A few fields of soybeans were planted very late (into mid or late-July) and those soybeans were not as developed at the freeze event. The soybeans in these images were planted late, but they were dropping leaves and the pods were already bronze instead of green. Seeds in these pods were yellow-green instead of green. These seeds had reached full weight and had just started to dry down when the freeze hit.

The freeze most likely will slow down the drying process in this field. The farmer will have to decide between a much later harvest or harvesting wetter seeds earlier. 

If the pods and/or soybeans were green at the freeze event, then the seeds may not ever dry down properly. If there was a lot of viable green material at the time of the freeze events, these soybeans could be candidates for silage, depending on whole plant moisture. Consultation with an animal nutritionist should occur before trying to make silage from soybeans.

Mature Pod Color on Freeze Damaged Soybeans.
Image courtesy of Curt Judy
Our friends further north deal with freeze events on soybeans on a more regular basis. They have some really good information on this topic.

How to Manage Frost-Damaged Soybeans (Michigan State)
Effect of Freezing on Soybean Seed Yield and Composition (Wisconsin)
Odds my Soybean Crop will mature before a killing frost hits (Wisconsin)
Assessing Frost Damage in Soybeans (North Dakota State)
Yellow-green seed on Freeze Damaged Soybeans.
Image courtesy of Curt Judy

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