September 30, 2019 | By: | Agronomy

Will My Crops Finish This Year?

We’re getting a lot of calls lately asking if the corn is going to finish. While I can’t predict when the first frost will come, there is some good university data available on staging and yield loss that can help you predict potential impact.

Ideally corn will get to black layer before we experience a killing frost meaning temps are near 32 degrees F for a few hours and near 28 F for a few minutes. If we have a killing frost before corn reaches R6 (black layer) there will be yield impacts.

This chart from the University of Wisconsin is a good guideline for estimating yield loss based on development stage and a frost event.

 Frost Impact on Corn Yields

Corn development  Killing frost

(Leaves and stalk)

Light frost

(Leaves only)

Stage  Percent yield loss
R4 (Soft dough)  55  35
R5 (Dent)  40  25
R5.5 (50% kernel milk)  12  5
R6 (Black layer)  0  0

Read the complete study from the University of Wisconsin here.

Frost Impact on Soybean Yields

Similar research has been published on the impact of frost damage to soybeans. Impact to soybeans occurs under 30F for an extended period of time. The following table shows the growth stages and potential impact of a killing frost on soybeans.

Soybean Growth Stage Days after bloom begins Days to maturity Percent of total
Begin Pod (R3) 15 68
Full Pod  (R4) 24  59
Begin Seed  (R5) 33  50 25
Full Seed  (R6) 48  35 47
Begin Maturity (R7) (One brown pod on plant) 73  10 95
Full Maturity (R8) (95% of pods are mature) 83  0 100

Read the full report here.

Scouting is key to predicting yield impacts. Scout regularly so you know what stage your crop is at when a frost event occurs.

Questions? Reach out! Call me or your Peterson Farms Seed dealer if you have questions about how to stage your corn or about your crop in general.

Adam Spelhaug, Agronomy Lead CCA

Adam Spelhaug

As the agronomy manager, Adam Spelhaug works diligently to determine the best genetics for our region, bringing growers what they need in their fields. Adam has been making his mark on Peterson Farms Seed since 2005. When he’s not discovering genetic breakthroughs, Adam can be found spending time with his family, golfing or bowhunting. He’s a North Dakota State University alumnus, and he’s proud of it. Don’t take any UND green into his office.

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