MANHATTAN- As the Kansas wheat crop begins to breakdormancy, concerns of winterkill are on the minds of producers. Two sub-zeroevents this winter with little to no snow cover may have frozen some wheatplants to death.

In most areas it is still too early to determine damage butwhen a polar vortex strikes with little to no snow cover, especially combinedwith poor soil moisture, the risk of damage is high. While snow cover savedsome areas from the freeze, Central Kansas lacked the protective white blanketfor the extreme cold temperatures.

"The wheat crop is currently more fragile than we would likebecause of drought and cold temperatures," said Aaron Harries, director ofmarketing for Kansas Wheat.

Winter came earlier than expected this year leaving lesstime for wheat plants to develop before entering dormancy. Plants that arepoorly developed going into winter, with few secondary roots and no tillers aremore susceptible to winterkill.

Risk of winterkill is often determined by how low soil temperaturesget at the crown level of the plant. Dry areas are most susceptible to the coldas soil moisture can help soil retain heat, protecting the crop. The airtemperature above the soil may be 5 to 10 degrees but in moist soil thetemperatures can remain 20 to 25 degrees above zero.

The ongoing drought has caused low topsoil moisture,increasing the risk for winterkill. Topsoil moisture supplies as of January 27were rated 48 percent very short, 37 percent short and 15 percent adequate.

Producers are advised to contact their crop insurancerepresentative before making any management decisions on fields that havesuspected winterkill injury.

Jim Shroyer, Kansas State University extension agronomistsuggests if large areas of the field have winterkill but other areas are fine,it is best to avoid applying topdress fertilizer to the area where the wheathas died.

Plants that are killed outright will not turn green as theweather warms. Damaged plants will begin to green up then go backwards and die.There are enough nutrients in the crown to allowthese plants to green up, but the winter injury causes vascular damage so thenutrients that are left cannot move, or root rot diseases move in and kill theplants. Shroyer says that this slow death is probably the most common result ofwinter injury on wheat.

However, wheat is a hearty crop, built towithstand winter's storms. Last fall temperatures fell gradually, allowing thewheat crop to develop good winter hardiness. If the weather had gone from warmto extreme cold in a day, there would be more cause for worry.

"One general rule is that producers should not make anyquick decisions about the condition of their wheat crop after a freeze," writesShroyer in this week's agronomy eUpdate. "It will take several days of warmweather following freezes to evaluate the condition of the crop and its yieldpotential. Even if some of the main tillers are injured or killed, producersshould wait to see if enough other tillers have survived to compensate for thelost yield potential. Patience is key."

For a successful wheat crop weather conditions need toremain moderate throughout the next few months with an increase in rainfall.