Released: March 06, 2002

Sharp Temperature Drop Tough on Wheat

MANHATTAN, Kan. – The Kansas winter wheat crop went from idyllic spring-like weather into the deep freeze in a matter of hours in late February, which has Jim Shroyer concerned.

Shroyer, the wheat production specialist with Kansas State University Research and Extension, said that several consecutive days of mild weather in February had the crop in some parts of the state coming out of dormancy. A cold snap swept the state late in the month, and temperatures plummeted. That may have taken a further toll on a wheat crop that was already beset by dry weather.

"When wheat greens up, it loses its winter hardiness," the agronomist said. "When the temperature has been 60 or 70 degrees [F] for several days or more and then drops suddenly to 10, there could be some problems," he said.

"Wheat can reharden if temperatures go from warm to cold gradually," Shroyer said.

That wasn’t the case in late February, however, when temperatures in Russell went from a high of 72 degrees to a low of 30 on Feb. 23, according to Mary Knapp, state climatologist for Kansas. On the same day, temperatures at Hays fell from 64 degrees to 32 and Garden City went from 76 to 35.

Just a few days later, things got even colder. On Feb. 27, Dodge City dipped from a high of 41 degrees to a low of 5, and Hill City went from 37 degrees to -2. Readings at Hays plummeted from 21 degrees to -4, Knapp said.

Jagger, a popular hard red winter wheat in Kansas, is susceptible to damage from these kinds of temperature changes because it greens up early, Shroyer said.

"The injury is not evident immediately. As springtime weather warms, and plants come out of dormancy again, growers may just notice thinner plants or areas of fields that have died," he said. "That could be because of this last cold snap but it could also have come from a similar situation just after Christmas. The damage that we can see right now is not coming from the late February drop in temperatures. It more likely came from outright winterkill, or drought or army cutworm damage."

A lack of moisture had already left the crop in a precarious situation, with poor crown root development apparent in some areas, Shroyer said. As farmers go out to check why their wheat isn’t greening up, there are things to look for. It could be army cutworms, so they should look for larvae. In those cases the wheat will green up and then starting turning brown. In other areas that don’t green up at all, growers should check for loose, dusty topsoil. Wheat plants in such areas may have no root systems. That’s probably drought compounded by winterkill, he added.

River basin reporting stations from around the state recorded below-normal precipitation during February, Knapp said. The lowest were the Upper Republican Basin at 34 percent of normal and the Cimarron Basin at 37 percent of normal, while the Lower Arkansas Basin reported 73 percent of normal.

But the February readings generally revealed the continuation of a longer-term dry trend. The Cimarron River Basin precipitation for September 2001 through February 2002 came in at 46 percent of normal and Upper Arkansas River Basin posted precipitation at 62 percent of normal. Other areas fared somewhat better, however, with the Upper Republican posting the highest percent-of-normal precipitation at 92 percent of normal for the September-February period.

Spring moisture will be especially important to wheat growers this year, given that many areas are already facing a deficit.

"Normally we get twice as much precipitation in March as we do in February, so if we get half of normal precipitation in March, it’s a lot worse than getting half the normal precipitation in February," Knapp said.

On March 4, the Kansas Agricultural Statistics Service rated the Kansas wheat crop condition as12 percent very poor, 24 percent poor, 38 percent fair, 24 percent good, and 2 percent excellent. "Statewide, wheat remains drought-stressed with a poorly developed root system, particularly in western districts," KASS reported. "Moisture amounts received in many areas have not been sufficient to improve wheat condition. As wheat begins to come out of dormancy, significant amounts of moisture will be needed."

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Mary Lou Peter, Communications Specialist
mlpeter@oznet.ksu.edu
K-State Research& Extension News