Battle for the Belt: Season 2 Episode 5- Freeze Injury to Corn and Soybean

Ohio experienced overnight cold temperatures between April 21st and April 22nd . Early planted corn and soybeans were subjected to frost damage with air temperatures lingering under 30ºF for about five hours, with the low reaching 28ºF.

Freeze damage on corn

Corn at the Western Agricultural Research Station was at V1 when temperatures dropped to freezing. At the V1 growth stage, the growing point is about ¾-inch below the soil surface. The growing point is above ground at the V6 growth stage. Damage to the above-ground leaf tissue (Figure 1) is not detrimental to the crop and leaves can grow back as long as the damage did not affect the mesocotyl and crown, below the soil surface. The mesocotyl and crown should be white when healthy and brown when killed by the frost (Figure 2). Air temperatures between 28ºF and 32ºF can result in tissue damage, but soil temperatures of 28ºF can result in plant death. To assess frost damage, evaluate the crop at least 3 to 5 days after the cold temperatures to see if there is regrowth or death of the growing point.

Figure 1. March 25^th planted corn, 24 hours after frost at the Western Agricultural Research Station

Figure 2. Uprooted corn, showing a healthy mesocotyl and crown at the Western Agricultural Research Station.

Freeze damage on soybean

Soybeans are in danger of frost damage with the same temperatures as corn, between 28ºF and 32ºF. However, the soybean growing point is above ground at emergence, and the apical meristem is at the cotyledons. If there is damage above the cotyledons, the crop can put on new growth and survive, but if the damage is below the cotyledons, at the hypocotyl or the crook of the soybean that emerges from the ground first, then the plant cannot recover (Figure 3). To assess damage, look at the hypocotyl to see if there is discoloration. If the soybeans have not yet emerged, then there should be limited damage.

What’s happening in the field?

As seen above, corn and soybean plants had visual injury from recent freeze events. However, the corn had healthy growing points and will likely grow out of the damage and only a few soybeans sustained lethal damage. Other soybean studies planted the same day (March 25th) at the same location sustained much more frost damage, we think because of the difference in soil type and tillage practices.

The Wooster campus was able to plant the first planting date of corn and soybeans on April 22^nd after weeks of saturated soils (Table 1). Table 2 presents the weekly (April 22 to April 28) weather conditions for planting dates one and two at the Western location and planting date one at the Wooster campus. The first planting date at the Northwest research site is forthcoming.

 Table 1. The planting date conditions for planting date one at the Wooster Campus, 2024.

Table 2. Weekly weather conditions for planting dates one and two at the Western location and planting date one at the Wooster campus, with day of planting, soil, air temperature averages, and Growing Degree Days (GDDS) from April 22 to April 28. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).