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First hollow stem update 03/05/2014

First hollow stem is the optimal time to remove cattle from wheat pasture (full explanation). We measure first hollow in our September-sown wheat forage plots at Stillwater each year, and normally have approximately 50% of varieties at or past first hollow stem by March 1st. I have posted first hollow stem measurements from these plots in a table at the end of this blog. No varieties are currently at first hollow stem at Stillwater, but I anticipate the small amount of moisture gained from recent snow and warming temperatures will spur onset of first hollow stem over the next week or so. We will take another set of measurements on March 10 and report the results on this blog.

Keep in mind that the numbers reported from Stillwater are likely behind those being observed in southern Oklahoma and ahead of those observed in northern Oklahoma. Dillon Butchee in the Altus area reported finding first hollow stem in Jagger last week. The First Hollow Stem Advisor on the Oklahoma Mesonet indicates that  early varieties in southern Oklahoma are likely past first hollow stem and that early varieties in central Oklahoma will reach this point within a week. Keep in mind the one week projection uses historical weather conditions which exceed our current forecast. Cooler than normal conditions will not last forever, though, and my advice is to move cattle off of wheat pasture in southern Oklahoma yesterday, start moving them off of wheat pasture in central Oklahoma today, and move cattle off wheat pasture in northern Oklahoma next week.

Probability of first hollow stem for early varieties 03/05/2014

Probability of first hollow stem for early varieties 03/05/2014

One week projected probability of first hollow stem for early varieties 03/05/2014

One week projected probability of first hollow stem for early varieties 03/05/2014

Variety cm of hollow stem 03/05/2014
Endurance 0.00
Deliver 0.00
Pete 0.24
OK Bullet 0.00
OK Rising 0.00
Billings 0.62
Ruby Lee 0.04
Garrison 0.22
Duster 0.00
Gallagher 0.39
Iba 0.00
Everest 0.29
Jackpot 0.12
Doans 0.00
Greer 0.31
CJ 0.02
SY Southwind 0.11
Exp F14 0.03
Armour 0.22
WB-Cedar 0.51
WB-Redhawk 0.66
WB-Grainfield 0.10
Winterhawk 0.09
WB4458 0.00
T153 0.00
T154 0.23
T158 0.02
LCS Mint 0.02
LCS Wizard 0.02
LCH11-109 0.11
LCH11-1117 0.10
LCH11-1130 0.16
TAM 112 0.14
TAM 113 0.77
Byrd 0.12
Brawl CL Plus 0.00
Centerfield 0.00
Doublestop CL Plus 0.03
OK09125 0.00
OK09520 0.03
OK10126 0.00
OK08707W-19C13 0.02
OK10805W 0.02
OK10728W 0.02
OK11754WF 0.77
Average 0.15

First hollow stem advisor available on Mesonet

First hollow stem occurs just prior to jointing and is the optimal time to remove cattle from wheat pasture. A new first hollow stem advisor tool available on the Oklahoma Mesonet provides Oklahoma wheat farmers a real time assessment of the current first hollow stem situation in the state and a forecast for the next two weeks. While the first hollow stem advisor is a valuable tool, it is not a substitute for scouting, as conditions in your field may vary from the estimates provided.

The advisor uses a mathematical model that predicts the probability of first hollow stem based on soil heat units and wheat first hollow stem category (early, middle, or late). The model was developed by J.D. Carlson at OSU using first hollow stem data from the wheat variety testing program, and model development was made possible through a grant from the Oklahoma Wheat Commission.

You can navigate to the first hollow stem advisor from www.mesonet.org by clicking on “Agriculture” then “Crop-Wheat”  and looking for First Hollow Stem Advisor on the lefthand menubar. Or you can click here.  

Screen Shot 2014-02-14 at 1.01.50 PM

Once you are at the first hollow stem advisor page, you will need to make a few selections. First, you have an option of viewing a statewide map or you can view data for a particular site in a table or graph. Next, you can select whether you want to view the current situation or a projection for the next one or two weeks. Finally, you will need to indicate if your variety falls into the early, middle, or late category. Click on the “look up by category” link if you are unsure where your variety falls.


Above is the statewide map for current conditions as of 14 February 2014. Other than a hot spot near Ardmore, there is less than 5% probability that we are at first hollow stem in Oklahoma. Note, however, that many locations are near the 576 heat unit threshold for 5% probability of first hollow stem. This is where the projection tools come in handy.


The map above is the two-week first hollow stem projection through 28 February 2014 (i.e the map was created on 14 February 2014). These projections are based on historical weather data for the next two weeks, and do not take into account the current forecast which might be warmer or colder than the historical average. Note that almost the entire state up to I-40 is predicted be at or above the 25% probability level for first hollow stem by February 28. It is recommended that you start scouting once the advisor predicts a 5% probability of first hollow stem in your area. If you are going by the first hollow stem advisor alone (not recommended) cattle should be removed no later than when a 50% probability of first hollow stem has occurred.

First hollow stem nearing

First hollow stem occurs just prior to jointing and is the optimal time to remove cattle from wheat pasture. Given the warm forecast for the next two weeks, it is likely that we will start seeing first hollow stem in Oklahoma wheat fields. Grazing past first hollow stem can reduce wheat grain yield by as much as 5% per day and the added cattle gains are not enough to offset the value of the reduced wheat yield.

Similar to previous years, we will monitor occurrence of first hollow stem in our wheat plots at Stillwater and report the findings on this blog. There is also a new first hollow stem advisor available on the Oklahoma Mesonet that can assist in determining when to start scouting.

Checking for first hollow stem is fairly easy.

  • You must check first hollow stem in a nongrazed area of the same variety and planting date. Variety can affect date of first hollow stem by as much as three weeks and planting date can affect it even more.
  • Dig or pull up a few plants and split the largest tiller longitudinally (lengthways) and measure the amount of hollow stem present below the developing grain head. You must dig plants because at this stage the developing grain head may still be below the soil surface.
  • If there is 1.5 cm of hollow stem present (see picture below), it is time to remove cattle. 1.5 cm is about the same as the diameter of a dime.
  • Detailed information on first hollow stem can be found at www.wheat.okstate.edu under ‘wheat management’ then ‘grazing’
  • Image

Grazing considerations: crown roots and first hollow stem

There are a few cattle already on wheat pasture in Oklahoma and more that will be turned out in the coming weeks. An adequate crown root system is required to anchor wheat in place prior to grazing.

Wheat should not be grazed until enough crown roots are present to anchor the plant in the soil

Wheat should not be grazed until enough crown roots are present to anchor the plant in the soil

Without these roots, wheat can be pulled from the soil during grazing, thinning final stands. Aboveground appearances can be deceiving, so it is important to pull plants from the soil to ensure the crown roots are there even if the plants appear large enough for grazing.

It is also important to make preparations for measuring first hollow stem prior to turning cattle out on wheat pasture. Grazing delays plant development; therefore, first hollow stem has to be checked in a nongrazed area. The nongrazed area does not have to be large and can be achieved through a panel exclosure or by simply moving one of the posts for an electric fence in a few feet. The key is to plan for the nongrazed area now so you can measure first hollow stem in February.

First hollow stem update 03/08/2013

We are not progressing towards first hollow stem as quickly as I anticipated, but most varieties are getting close. The drought has likely slowed onset of first hollow stem. Keep in mind that drought stressed wheat might need longer to recover from grazing, so it will likely be better to remove cattle a little early in 2013.


                 cm of hollow stem

Variety           03/06/13

Jagger             .

Endurance       0.46

Deliver             0.43

Pete                 0.4

Ruby Lee         1.3

Garrison           1.44

Duster              0.49

Gallagher        .

Iba                   0.78

Fuller               1.99

Everest           .

Jackpot            1.69

Doans              0.55

Greer               .

CJ                    0.38

Razor               .

Armour             1.7

WB-Cedar        0.82

WB-Redhawk    2.71

T153                2.27

T154                2.44

T158                0.5

OK08328         0.36

*Average of ten hollow stem measurements in wheat sown 09/20/12 at Chickasha, OK


                 cm of hollow stem

Variety            03/05/13

Jagger                 1.1

Endurance          0.2

Deliver                 0.7

Pete                    0.3

OK Bullet            0.5

OK Rising            0.7

Centerfield          0.3

Ruby Lee             2.4

Garrison               1.6

Duster                  .

Gallgher              0.7

Iba                       0.1

Billings                0.4

Fuller                   1.8

Everest                .

Jackpot                1.5

Doans                  1.7

Greer                   0.5

CJ                        0.2

Razor                   2.8

Armour                1.2

WB-Cedar            1.1

WB-Redhawk       0.9

WB-Duece CL+    .

WB-Grainfield      0.7

Winterhawk          1.2

WB-4458             .

T153                   1.7

T154                   2.0

T158                   0.1

LCS Mint             0.1

LCH08-80            0.1

LCH08 – 109        0.3

T173                   0.4

Byrd                     0.1

Brawl CL+            0.1

TAM 113             0.4

OK09915C          0.4

OK09935C          0.4

OK09634             0.5

OK09125             0.4

OK09528             0.2

OK09729             0.4

OK08328             0.1

*Average of ten hollow stem measurements in wheat sown 09/18/12 at Stillwater, OK


Onset of first hollow stem was affected by severe drought stress

First hollow stem update – 03/01/2013

The OSU Small Grains Extension team checked first hollow stem at Chickasha and Stillwater this week. Measurements from both locations are provided in the tables below. Varieties with 1.5 cm or more of hollow stem are considered to be at first hollow stem. Numbers have not changed much at Chickasha due to the cold weather; however, with temperatures climbing into the 60’s next week we should see rapid progression of first hollow stem. Although planted a few days earlier, Stillwater is about a week behind Chickasha in terms of first hollow stem. This is due to severe drought stress at Stillwater. In fact, there were a few times I questioned wether or not the Stillwater plots would survive. In this situation it is important to not only consider first hollow stem but also the amount of green leaf area remaining after grazing. Wheat with less than 60% ground cover at jointing will likely not achieve full grain yield potential, even if cattle were removed prior to first hollow stem.


                     cm of hollow stem

Variety               02/28/13

Jagger                   2.5

Endurance             0.1

Deliver                   0.3

Pete                       0.2

Ruby Lee               1.1

Garrison                 0.8

Duster                    0.5


Iba                         0.4

Fuller                     1.5

Everest                 –

Jackpot                  0.7

Doans                    0.4

Greer                     1.6

CJ                          0.8

Razor                     4.0

Armour                   1.0

WB-Cedar              1.1

WB-Redhawk          1.1

T153                      1.2

T154                      1.0

T158                      0.3

OK08328               0.4

*Average of ten hollow stem measurements in wheat sown 09/20/12 at Chickasha, OK




                     cm of hollow stem

Variety               02/27/13

Jagger                     0.4

Endurance              0.1

Deliver                     0.7

Pete                        0.3

OK Bullet                0.1

OK Rising                0.4

Centerfield              0.3

Ruby Lee                 1.2

Garrison                   0.5

Duster                      0.0

Gallgher                  0.3

Iba                           0.0

Billings                    0.2

Fuller                       0.5

Everest                    2.3

Jackpot                    0.8

Doans                      0.5

Greer                       0.4

CJ                            0.0

Razor                       0.6

Armour                    0.1

WB-Cedar                0.6

WB-Redhawk           0.9

WB-Duece CL+        4.2

WB-Grainfield          0.4

Winterhawk              0.6

WB-4458                 1.6

T153                       0.9

T154                       0.7

T158                       0.1

LCS Mint                 0.1

LCH08-80                0.0

LCH08 – 109            0.2

T173                       0.0

Byrd                         0.2

Brawl CL+                0.2

TAM 113                 0.3

OK09915C              0.1

OK09935C              0.1

OK09634                 0.0

OK09125                 0.1

OK09528                 0.0

OK09729                 0.2

OK08328                 0.1

*Average of ten hollow stem measurements in wheat sown 09/18/12 at Stillwater, OK


Onset of first hollow stem was affected by severe drought stress