A hard freeze in parts of Kansas in the early morning hours of April 14 may have damaged the most advanced tillers in earlier planted wheat in south central and southeast Kansas, but hopefully the damage will not be as severe or as widespread as the freeze damage in April of 2007, says Jim Shroyer, K-State Research and Extension agronomy state leader.
"The wheat is not as far along in development this year as it was at the time of last year's freeze, and the temperatures did not get as cold this year. Where some of the tillers have been damaged, there is still plenty of time for undamaged tillers to compensate and minimize any potential yield loss," Shroyer says.
Wheat in the jointing stage can sustain damage from temperatures in the low 20s for several hours, he said. In the boot stage, wheat is susceptible to damage from two hours or more of temperatures in the upper 20s. Some of the early-planted wheat in south central and southeast Kansas was at the jointing stage on April 14, and primary tillers may have been damaged in some cases. Later-planted wheat is less developed and should have escaped damage.
The best thing producers can do for the first few days is simply walk the fields to observe lodging, crimped stems, and damaged leaves, the agronomist says.
"Be patient. Do not take any immediate actions as a result of this freeze, such as destroying the field for recropping. It will take several days of warm weather to accurately evaluate the extent of damage," Shroyer says. "After several days, producers should split open some stems and check the developing head. If the head is green or light greenish in color and seems firm, it is probably fine. If the head is yellowish and mushy, it may have freeze injury."
There are some early signs producers might have noticed right away.
• Silage smell. If a field of wheat is giving off the aroma of silage, that indicates that leaves have been damaged.
• Ice in the stems. If there was ice in the stems below the first node the morning of the freeze, those tillers will probably be damaged (although not always) and may not produce grain.
• Lodging. If the wheat lodged immediately after the freeze, that indicates stem damage. Later tillers may eventually cover the damaged tillers.
Producers should remember that even if primary tillers are damaged, less-developed secondary tillers may be fine, Shroyer says.
"If there are enough secondary tillers that survive, these tillers should be able to compensate and keep yield losses to a minimum – assuming temperatures did not get into the teens," he explains.
More information on freeze damage to wheat is available in "Spring Freeze Injury to Kansas Wheat," K-State Research and Extension publication C646, available at county and district Extension offices and on the Web at: http://www.oznet.ksu.edu/library/crpsl2/c646.pdf.