KSU: Fields should be watched closely following freeze




K-State Research and Extension

MANHATTAN — A hard freeze — with temperatures well into the teens in western Kansas Tuesday and Wednesday — will almost certainly damage the wheat crop to some extent, said Jim Shroyer, K-State Research and Extension crop production specialist. Central and eastern Kansas also experienced freezing weather, but temperatures there were mostly in the upper 20s instead of the teens.

"The good news is that the wheat crop is not nearly as far along in development as it was at this time last year due to the drought, but any wheat at the jointing stage or later will probably lose some tillers where temperatures were in the teens for an extended time," Shroyer said.

Where only some of the tillers have been damaged, there is still time for undamaged tillers to compensate and minimize any potential yield loss, but that will depend on having adequate moisture, which is uncertain this year, he added.

Wheat in the jointing stage can usually tolerate temperatures in the mid to upper 20s with no significant injury, Shroyer said. But, if temperatures fall into the low 20s or even lower for several hours, the lower stems, leaves, or developing head can sustain injury.

"If the leaves of tillers are yellowish when they emerge from the whorl, this indicates those tillers have been damaged. Existing leaves may also be damaged so severely that they turn bluish-black and water-soaked in appearance, then bleach out. This usually results in the field's having a silage smell," he said.

Wheat that hasn't started to joint yet will probably suffer damage to the existing foliage, but the growing points will be protected by the soil and should escape injury, he added.

"This wheat will have cosmetic damage to the leaves that will show up almost immediately. If new leaves emerging over the next few weeks are green, that will indicate that the growing points survived and the plants will still produce tillers. If the new leaves are yellow, the growing point of that particular tiller was killed by the freeze," Shroyer said. "The best thing producers can do for the first few days is walk the fields to observe lodging, crimped stems and damaged leaves."

"Be patient. Do not take any immediate actions as a result of the freeze, such as destroying the field for recropping. It will take several days of warm weather to accurately evaluate the extent of damage," he said.

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.

If the main tillers are injured, secondary tillers may begin growing normally and fill out the stand, Shroyer added.

"The wheat may look ragged because the main tillers are absent, but enough tillers may survive to produce good yields, if spring growing conditions are good. If both the main and secondary tillers are injured, the field may eventually have large areas that have a yellowish cast and reduced yield potential," he said.

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