Ag Line:
Hard freeze devastates
By Wade Parker County Extension Coordinator

History was in the making Sunday morning as a blast of arctic air pounded the southeastern United States. The low reached 25 degrees F in many areas, and I have actually heard of some reports of 22 degrees. In December and January this can be a common occurrence, but it has been years since temperatures have dipped this low for this time of year. You think you have seen it all with weather patterns until something as bizarre as this occurs!

What is the effect of the weather on plants? From an agricultural production standpoint, peaches, pecans, small grains, and corn are on the chopping block. The corn I have looked at has varying levels of damage. In my opinion all of the corn has been damaged, but at varying levels in the field. The million dollar question is, will this corn survive? The very young emerged corn (<1 week) has a better chance of surviving, while the older emerged corn (>2 weeks) will take much longer to recover. The reason behind this lies in the position of the growing point. The younger corn's growing point was still insulated in the soil, the older was exposed to cold temperatures. The bottom line is we are going to have to wait and see what happens. If the temperatures rebound, corn will have a better chance of rehabilitating.

The effect of the cold snap on small grains is undetermined. I looked at several wheat fields Monday morning and did not see any visible damage to the leaf tissue. However, just because you don't see any visible damage does not mean that damage has not occurred. In freezing temperatures like Sunday morning, the male parts of the flowers in the spikes die because they are more sensitive to low temperatures than the female parts. Since wheat is self-pollinated, sterility caused by freeze injury results in poor kernel set and low grain yield. Injury can be detected soon after freezing by examining the anthers inside each floret. Anthers are normally light green and turgid when young and become yellow about the time they are extruded from the florets after anthesis or flowering. The anthers also will become twisted and shriveled within 48 hours after a freeze. Eventually, the anthers turn a whitish-brown. Freezing temperatures that are severe enough to injure leaves and lower stems are nearly always fatal to male flower parts, but less severe freezing may cause sterility without any symptoms appearing on plant vegetative parts. Unfortunately, this is exactly what I am seeing in fields. Just like the corn and everything else, we will have to wait and see.

I am urging people with gardens and our farmers to not rush into any major decision this week. We do have some options available on planting alternative crops and possibly re-planting corn with different maturity dates. Please do not hesitate to call for assistance.

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