Update from the Field: Jack Frost Nipping at Your Nose
Posted by Dave Dyson, Agronomist on May 26, 2020
Last week’s low temperatures not only produced a frost, but a hard freeze. A hard freeze is defined as temperatures dropping to 28 degrees Fahrenheit for at least four hours. The chart in Figure 1 shows a frost or hard freeze is unusual for the middle of May. The cold event experienced last week could cause havoc for specialty crops that were planted, but for the corn, soybeans, and wheat, the most damage I saw was leaf burning.
Figure 1: This chart from https://www.thespruce.com/first-and-last-frost-date-2539701, shows the average first and last frost for the United States.
The wheat crop in the Eastern Corn Belt was mostly between the jointing and boot stage when the cold weather hit. The University of Illinois has a good chart, Figure 2, showing the different stages of wheat. Jointing is when the plant moves from a flexible grass plant to a rigid stalk. The boot stage is when the head is in the stalk but not yet visible. While the head is protected by the stalk, the crop can overcome colder weather and the yield will not be affected, Figure 3.
Figure 2: This chart from the University of Illinois shows the different stages wheat goes through during its life cycle. Jointing is when the plant moves from a flexible grass plant to a rigged stalk. The Boot stage is when the head is the stalk but not yet visible. https://www.westco.coop/pages/custom.php?id=33411
Figure 3: This chart from Kansas State University shows the different stages of wheat and the potential damage caused by low temperatures. https://www.sunflower.k-state.edu/agronomy/wheat/freeze_damage.html
Growers started planting corn around April 15th, and those plants were at V1-2 during the freezing weather last week. The weather prior to the freeze was warm and dry, so the soil temperature was up into the mid-60s. This helped prevent the little seedlings from freezing out, but I have noticed some leaf tissue burn on emerged plants during the frost, Figure 4. This will not damage the growing point of the plant, since the growing point will not be above ground-level for another four weeks. If the ground had been cold enough to freeze the growing point, we would have been talking replant,. However, since the ground was warm, the plants will survive to grow another day.
Figure 4: This picture was taken 5/16/20 in Peru, IN. This corn seedling was planted on 4/20/20 and withstood a hard freeze on 5/9/20. This plant is at V2 but the first leaf, the rounded leaf, was frozen off. This will make staging this corn plant very difficult during the year.
Soybeans can be a little trickier as the growing point on a soybean plant is at every axillary node of the plant. That is why right before R1 stage of the plant there is a prescription to use a Protoporphyrinogen oxidase (PPO) inhibiting herbicide, or group 14, to chemically burn off the top growing point making the plant “bush” out and produce higher yields. The problem with little seedlings is there may only be one growing point until V2, several weeks from now. If the frost would freeze out the only growing point, the plant will not grow out of the frost damage. Walking your emerged soybean fields a week after a frost is the best way to determine how many plants were damaged. Luckily, most soybean fields survived the frosty weather and are continuing to grow through the tissue damage.
To help crops through the frost damage, apply 1 pt/ac of Phosfix®. This is my standard recommendation with a PPO application as well. The application of Phosfix helps to hurry the healing process in the plant following the side effects of the PPO application or frost damage. Phosfix contains cytokinins, gibberellic acid, and auxins that help with cell division, cell elongation, and cell differentiation, respectively.
In conclusion, the frost did do damage to our crops that were emerged; it did not kill the crop but burned the exposed tissue. An application of Phosfix will help the crops to recover, similar to its performance when applied with a PPO inhibiting herbicid. Contact your local sales representative from The Andersons for help in determining and mediating frost damage, or complete this form.
Dave Dyson is a regional agronomist for The Andersons’ Farm Centers which are located throughout Ohio, Michigan, and Indiana. He is an Indiana native and grew up on a dairy farm in Miami County. A graduate of Purdue University with a degree in Crop & Soil Science, Dave has a deep knowledge of various agronomic topics and is committed to helping growers improve their crops. If you have any questions, Dave can be reached at email@example.com.
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