1. Kansas wheat freeze injury update 1 2. Wheat freeze injury in Saline County 3

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1 Number 187 April 13, Kansas wheat freeze injury update 1 2. Wheat freeze injury in Saline County 3 1. Kansas wheat freeze injury update Freeze injury to wheat in the south central Kansas counties of Sumner, Harper, Kingman, Sedgwick, and Pratt ranges from significant to slight, based on conditions as of April 10. The extent of damage varies from field to field. In about half the fields examined, many of the main tillers were dead. Some of this damage appeared to be from the freeze of March 28 since the heads seemed to have been dead for quite some time. But the freeze of April 6 clearly did damage, as well. Where the main tillers had died, symptoms include: * Purplish leaf sheath around the stems * Heads in the stem that are water-soaked and off-color instead of turgid and white * Yellow leaves emerging from the whorl * Leaves around the growing point that are stuck together and hard to unroll * Desiccated plants 1

2 Main tillers on damaged wheat in Kingman County on April 10. Note the purplish color of the leaf sheaths. Photos by Jim Shroyer, K-State Extension Agronomy State Leader. The tiny head inside this stem has been damaged by the freeze. The head should be turgid and white, with a green midrib. Instead, it is slightly mushy and off-white to brownish in color. Where the main tillers have been killed by freeze, it is possible that secondary and tertiary tillers will be released from apical dominance and make it to harvest, if weather conditions are favorable for the remainder of the growing season. In addition, more tillers may develop if the weather stays cool. This can help compensate for yield reductions from the loss of the main tillers. The weather from this point on will be important to the success of wheat that has lost its main tillers to freeze damage. 2

3 Leaves on wheat plants injured by freeze will often turn yellowish or brownish. This may happen to the entire plant, or just the newer leaves coming out of the whorl. In addition, the leaf sheath will turn purplish. There is not as much freeze damage to the lower stems so far this year as there was after the freeze in That s because the wheat growth at the time of the freeze was not as lush and rank this year as it was in There appears to be less damage to the heads and stems in Pratt County, and areas north of there. That s not to say there is no damage, just not as widespread as the damage in far south central Kansas. That s also the case in areas west of U.S. Highway 183. There is less freeze damage in southwest Kansas, overall, than in south central Kansas, especially where wheat had been grazed, although some of the early-maturing varieties do have some damage. The severe and extended drought during the winter and spring, until the recent heavy snows, have been the main problem for wheat in that area. In northwest Kansas, the wheat is not as far along in development as in southern Kansas, and can withstand any loss to main tillers that may have occurred with few problems. If any main tillers were lost, secondary tillers will rapidly fill in and producers should notice little or no effect. The main problem in northwest Kansas has been dry topsoils, which has helped slow the growth and development of wheat in that area. -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu -- Kent Martin, Southwest Area Crops and Soils Specialist kentlm@ksu.edu -- Brian Olson, Northwest Area Crops and Soils Specialist bolson@ksu.edu 2. Wheat freeze injury in Saline County Freeze injury to wheat can be seen at this point, although producers still need to give the wheat more time before assessing the extent of any damage. An examination of wheat in Saline County on April 9 found: * The wheat was well into Feekes growth stage 6 with the 1st node already set at about 1-1.5" in all of these varieties with the growing point at least another 1" higher. * A few heads that were damaged on main tillers. * Suspicious main and secondary tiller heads in early-maturing varieties, such as Overley, Fuller, Santa Fe, Jackpot, and Shocker. These ranged anywhere from looking a little feathery, offcolor, watery, and so on. 3

4 Compared to 2007, this year's crop, for the most part, was not as advanced in development at the time of the freeze. In 2007, the temperatures remained cold, in some cases below freezing, for three days, so damage was slow to appear. The two days immediately after the freeze this year were warm with sunny afternoons. This year, I'd expect to see a general burning down then yellowing in fields where the main tillers were killed, and then a regreening as tertiary or undamaged tillers extend through the damaged canopy. The first photo below shows the regreening that occurred in 2007 in some cases. Cut open the stems and examine the heads to see if they are healthy or damaged, as illustrated in the other photos below from

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6 Photos by Stu Duncan, K-State Northeast Area Crops and Soils Specialist -- Stu Duncan, Northeast Area Crops and Soils Specialist These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e- Update Editor. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 6