Winter Wheat at Advanced Growth Stages due to Warm Winter in KY

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky
Lloyd Murdock, Emeritus Extension Soil Specialist, University of Kentucky
Edwin Ritchey, Extension Soil Specialist-Princeton, University of Kentucky

Table 1. Wheat plants at jointing (Feekes 6).

Unseasonably warm temperatures in KY since wheat planting (October 15, 2016) may become a major challenge to wheat yield and profitability this year. Since Oct 15, 2016, KY has accumulated about 2000 GDD growing degree days (GDD) or heat units. In most years, only about 1500 GDD are accumulated by mid-February, while 2000 GDD are typically accumulated around the end of March in KY.

These extraordinarily warm days and large number of GDD have resulted in wheat crops that are at a more advanced growth stage for this time of year. Typically, most of KY wheat in mid-February is beginning to break dormancy and initiate active growth: Feekes 3, Green-up. However, there are several reports in KY that wheat is jointing (Feekes 6; Figures 1 & 2).

This is very concerning because at jointing (Feekes 6) the growing point (developing wheat head) is above the soil surface and is vulnerable to damage, including freeze damage. The risk of freeze damage is quite high because throughout KY there is still at least a 6 to 9 week window that a freeze typically occurs (Table 1).

Figure 2. Wheat plant at jointing with dissected wheat head. 

Table 1. Probabilities for the date of the last spring freeze (32°F) in Kentucky based upon data from 1981 to 2010 (Arguez et al., 2010 provided by S. Foster, State Climatologist for Kentucky). Probabilities that the last spring freeze will occur on or after the date listed. For example, for 90% probability the last spring freeze will occur on or later than the date listed 90% of the time (nine out of ten years), while at the 10% probability level the last spring freeze will occur on or later than the dates listed 10% of the time (one out of ten years).

Kentucky Location	Date of Last Spring Freeze (32°F or less) in Kentucky by Probability Level
	90%	50%	10%
Ashland	6-Apr	24-Apr	10-May
Bardstown	30-Mar	14-Apr	29-Apr
Bowling Green	25-Mar	9-Apr	25-Apr
Covington	2-Apr	16-Apr	2-May
Danville	27-Mar	11-Apr	27-Apr
Glasgow	29-Mar	13-Apr	27-Apr
Henderson	24-Mar	8-Apr	23-Apr
Hopkinsville	24-Mar	10-Apr	24-Apr
Leitchfield	14-Apr	28-Apr	15-May
Lexington	29-Mar	14-Apr	29-Apr
Mayfield	23-Mar	9-Apr	23-Apr
Monticello	3-Apr	20-Apr	5-May
Murray	17-Mar	2-Apr	18-Apr
Nolan River Lake	3-Apr	20-Apr	7-May
Princeton	29-Mar	13-Apr	29-Apr
Russellville	25-Mar	11-Apr	29-Apr
Shelbyville	16-Apr	29-Apr	14-May
Somerset	3-Apr	20-Apr	6-May

 

Considerations:
• For wheat crops that have not received any nitrogen, consider a single nitrogen application as late as Feekes 6 or 7 growth stage. Delaying nitrogen application may reduce plant growth and the risk of freeze damage.
    o Research in KY has shown that with sufficient tillers, nitrogen application can be delayed as late
       as Feekes 6 or 7 with little or no yield reduction.
    o Normally nitrogen is applied by Feekes 5 or 6 to maximize yield. With the accelerated growth
       this year, delaying nitrogen application until Feekes 6 or 7 could retard wheat development and
       provide additional freeze protection, depending on when a freeze occurs.
    o Yield will be reduced if nitrogen application is delayed beyond Feekes 7, such as delays due to
       weather or field conditions.
• For wheat crops at jointing, Feekes 6, that have already received nitrogen applications, there is nothing that will protect the crop from freeze damage. The best approach is to consider delaying the second nitrogen application until Feekes 6 or 7, potentially reducing the severity of freeze damage.
• Freeze injury occurs when temperatures fall to 24°F or below for 2 or more hours at the jointing growth stage: Feekes 6.
• If freezing temperatures remain above 24°F there is only a slight risk of freeze damage.
• In Western KY, the wheat crop does not appear to be as advanced as other areas of the state. Last fall there was a considerable drought that may have resulted in ‘dormant’ wheat in the fall (due to lack of water) when other areas of the state wheat was actively growing. These areas will likely be most profitable following ‘normal’ wheat management recommendations.
• Be prepared to scout fields much earlier than usual for insects and plant diseases. The warm winter temperatures have also resulted in greater insect populations in KY, specifically cereal aphid species, which may increase the incidence of barley yellow dwarf virus.

Preparing for the Winter Wheat Planting Season

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

The optimal planting window for winter wheat in Kentucky is quickly approaching: October 10-30. Prior to the physical planting of wheat, farmers must make several critical decisions to maximize wheat grain yield and profitability the following June.  

Potential for Winter Wheat Freeze Injury

Wheat Head Freeze Damage, 2015. 
A freeze event (24°F or less for more than 2 hours)
occurred at Feekes 6 (jointing).

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

Much of Kentucky’s winter wheat crop is still tillering (Feekes 4-5; Figure 1) or just beginning to joint (Feekes 6; Figures 2 and 3). The weather forecast for this weekend is predicting that some areas of Kentucky will dip to 32°F or less. Given that most of our wheat is at Feekes 4 or 5, with some at Feekes 6, these temperatures are not cause for concern.  

Temperatures must be 12°F or less for 2 or more hours to injure wheat that is at the Feekes 4 or 5 growth stages, which much of our state is now.  For the more advanced wheat that is jointing, Feekes 6, temperatures must fall to 24°F or less for 2 or more hours.  Although the weather forecasts do not project conditions that we would expect wheat injury, examine weather data and scout your fields to determine is freeze injury occurred. 

Freeze injury can occur in small areas of fields, which are associated to low areas of fields where cold air settles.  Be sure and check for wheat stems damage close to the soil surface; characteristic symptoms of freeze damage are listed in Table 1.  It typically takes about 10 days of warm temperatures before injury can be seen.  Weather data can be accessed by clicking on the link of your county at wwwagwx.ca.uky.edu or www.kymesonet.org. 

Figure 1. Wheat field at Feekes 4 growth stage 

Figure 2. Wheat at Feekes 6 growth stage.
"Joints" are indicated with orange arrows.

Figure 3. Wheat at late Feekes 5/early Feekes 6 growth stage.
The "joint" (growing point; around the 1-3/8" mark) is right at
or slightly above the soil surface.  This 'joint' is visible
after the top few leaf sheaths were removed.   

Fall Nitrogen Considerations for Wheat in 2015

Edwin Ritchey, Lloyd Murdock, and Josh McGrath – Extension Soil Specialists, University of Kentucky

Many producers have completed or almost completed corn harvest and getting ready to start drilling wheat. One question that keeps coming up is the need for a fall nitrogen (N) application. In most years there is adequate residual N following corn. However most areas in Kentucky in 2015 had very good corn yields and a considerable amount of rainfall earlier in the season. Good corn yields coupled with high rainfall probably means that there is very little residual N remaining in the soil profile. Numerous studies at UK have not shown a consistent yield advantage to fall N applications for wheat. However, fall N does stimulate growth and establishment of the stand. Too much fall N could reduce yields by causing excessive growth and more winterkill.

Winter Wheat Meeting Today

Chad Lee, Extension Agronomist, University of Kentucky

The University of Kentucky Winter Wheat Meeting is scheduled for today, January 8, 2013 at the James E Bruce Convention Center in Hopkinsville, Kentucky. Topics include wheat row widths, adapting wheat to a changing climate, problems from the 2012 season and how the carry over into wheat, managing for higher prices, and others.

For the program, click here. 

New Wheat Publications

The Small Grains Variety Trials for 2009 is available at: http://www.ca.uky.edu/agc/pubs/pr/pr586/pr586.pdf

The Wheat Guide (ID-125) has been completely updated with new content, photos and format and is available at: http://www.ca.uky.edu/agc/pubs/id/id125/id125.htm

The Kentucky Small Grain Growers sponsored the updated version and is partly funding the printing of copies.

Printed copies of both publications should be available within several weeks. Both of these publications are linked to the Grain Crops Extension Website at: http://www.uky.edu/Ag/GrainCrops/

Marketing Winter Wheat

Wheat producers may be asking themselves if they should store or deliver wheat and if they store should they forward price or not. Currently, the wheat futures contract at the Chicago Board of Trade is offering a large positive carry (the difference in price between two futures contracts) for storing wheat from now into the fall. The gross return between July and December futures is 53 cents per bushel (6.23 for July and 6.76 for December) as of June 5, 2009. The July to September carry is 28 cents per bushel. The forward price benefit of 53 cents per bushel offers positive returns to storage, thereby making storage with a futures contract (a storage hedge) for fall delivery appealing since net return to storage is positive. To calculate net returns you should subtract variable costs to storage (this includes the interest cost of capital in the wheat), cost of insurance on wheat, and cost of shrinkage from the gross return of 53 cents. Also, any basis improvement between now and delivery would add to storage hedge returns. By Cory G. Walters, cgwalters@uky.edu