Cold Damage to Small Grains is Multifactorial

Frost damage to little grains is highly dependent on the stage of the crop. The actual subfreezing temperature reached the low temperature's duration, and the environmental conditions existed before the frost occurred.

Terry Gregoire, Extension Agronomist, says: "Small grains are one of the coldest tolerant crops. "From the earliest stages of development to germination, young grains can easily withstand temperatures of 25 F."

After mixing, the growth point moves above the ground and is vulnerable to frost damage. Slow to flower, young grains are hardy and can't withstand temperatures below 28 F, Gregoire says. But when the temperature is below 50 F for a few days before frost, small grain crops go through a tougher and more frost-tolerant period. Drought stress before frost can also cause the hardening of young grains and increase frost tolerance. Before being combined, the small hard grains have been shown to withstand temperatures as minor as 14 F.

Once the growing plant is above ground, it's more susceptible to frost damage, but Gregoire says that young grains can survive in the process of consolidating. Tolerate a temperature of 25 F without damage to the growing area, although the damage may occur more in the earlier stages.

Young grains are more susceptible to cold from the beginning of the flowering period, which is the time when the reproductive cells are developing. The anthers, the parts of this plant that produce seeds, are easily damaged by cold, which prevents or greatly reduces the production of seeds. Frost injury during flowering occurs when temperatures drop below 28 F. Barley is more susceptible to frost damage than wheat during boot because it flowers while still in the boot. The longer the temperature goes down, the greater the chance of injury, Gregoire says.

Small grain plants can avoid injury with a method called "super cooling", especially when the temperature cools slowly, explains Gregoire. Great cooling occurs when water from the plant's cells escapes - the effect is to lower the temperature at which the water inside the cells will freeze. This reduces the possibility of forming ice crystals and damaging the cells physically.

Assessing Damage

Before checking for frost damage, producers should wait two or three days for the damage to be easily seen. Most of the winter wheat fields are now in the flowering stage and are at high risk of frost damage. Checking these crops for damage involves separating the flowers and looking at the stamens, says Gregoire. A darkening of the water's appearance indicates the risk of frostbite. Damaged anthers will not release pollen. If pollination has already occurred, What should check the flowers for kernel development, which may take several days?

During the first development, the growing area of ​​the small grain plant is below the soil surface, so it is not damaged. Plants can lose their upper leaves to the ground without dying with this protection. Also, Gregoire advises producers to wait a few days to make an accurate risk assessment. By this time, new plant growth should have started.

"If it is not seen again, the stem of the plant may be split open to explore the growing area," explains Gregoire. "The growing point should be white or cream in color. Darkening or softening, with a watery appearance of the growing point, indicates danger and usually precedes the death of the plant."