Officials with the Hill County AgriLife Extension Service were looking last week to see if any of the early planted corn or winter wheat was damaged by last week’s freezing weather.

Some corn had been in the ground over a week when high temperatures went from the upper 70s to the mid 20s in just 24 hours.

The cold blast was accompanied by a blanket of sleet and ice across much of the county.

Extension Agent Ryan Collett said that temperatures in the teens, and holding below freezing for over 24 hours, raised the question of whether there might be freeze damage to crops.

“Even though there was no emerged corn in the area, there is still some concern about planted acreage,” he said.

The main concern with any freeze event shortly after planting is the impact on stand establishment.

Plant stand or population is a major component when determining corn yield potential. Significant reduction in plant stands below optimum levels would justify replanting.

Collett added, “The stage of development will determine the potential and type of injury to newly planted or emerged corn plants.

“The impact on newly planted (germinating seeds) and emerged plants should be discussed separately.”

For newly planted corn, the seeds will be in some stage of the germination process, depending on planting date, soil conditions and environmental factors.

Freezing temperatures are unlikely to reach seeds planted deeper than two inches, so officials were assuming that most planted seeds were not reached by lethal cold temperatures below 28 degrees.

However, soil temperatures below 50 degrees can damage germinating corn seedlings, which is known as imbibitional chilling injury.

As corn seeds imbibe or absorb water, the seed swells as the development process begins. Cell tissues that are cold because of absorbing cold water are less elastic and could rupture.

Symptoms of chilling injury include swollen kernels with slow growth of the root (radicle) or shoot (coleoptile) or seeds that fail to germinate at all.

Chilling injury shortly after germination could result in stunting or death of the root system, deformed elongation of the mesocotyl (known as corkscrew), delayed emergence or even complete failure to emerge.

Deeper plantings should buffer the seed from cold temperatures but given the severity of the freeze event, the degree of damage is uncertain, according to Collett.

For emerged corn plants, the key is the growing point. Damage to the growing point due to freezing temperatures will kill the plant and result in stand loss.

The growing point is below the soil surface until about the six-leaf stage, which protects it from minor frost/freeze events.

Even though the growing point is currently below the surface, the freeze could damage young seedlings, Collett pointed out.

For newly planted or recently emerged corn plants, time will be needed to access the extent of damage.

“Given the severity of this freeze event, stand loss is certainly a con-cern and replanting may be justified for fields with poor stands,” Collett added.

As for the winter wheat crop, which was planted in October and November, the verdict is still out.

Officials were looking closer at the early planted fields that might have advanced to the joint or reproductive stage. Those plants are more susceptible to freezing weather.

Most of the later planted wheat hasn’t advanced to that stage due to the cold weather experienced over the winter.

It was noted by the official that the cold weather discolored many of the wheat plants, but that doesn’t necessarily mean there is freeze damage.

Collett estimated it will be a week to 10 days after the freeze event before true damage assessments on the wheat crop can be conducted.

A late freeze in 2013 had producers north of the Hillsboro area baling their wheat crop, while other farmers left the crop in the field, which produced above average yields in many cases.

Source - http://hillsbororeporter.com/