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.
