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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 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’
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Checking for first hollow stem

First hollow stem occurs just prior to jointing and is the optimal time to remove cattle from wheat pasture. First hollow stem usually occurs in mid to late February in southern Oklahoma and early March in northern Oklahoma. 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
The plant on the left is past first hollow stem and is jointing. The plant on the right is at first hollow stem

The plant on the left is past first hollow stem and is jointing. The plant on the right is at first hollow stem

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.

hollowstem_early.current

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.

hollowstem_early.proj14day

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