First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8” or the diameter of dime) of stem below the developing grain head (full explanation). Because of the progress the plants have made at Stillwater, this update will be our final one for this location. Nine of the 11 wheat varieties that were examined earlier today reached or significantly surpassed the 1.5 cm threshold (Table 1). Doublestop CL Plus and Spirit Rider remain the final two hold-outs as they barely missed the threshold. Keep in mind that several factors influence the onset of FHS. These include the wheat variety, location, temperature, available moisture, grazing, and planting date (later sown wheat will typically reach FHS later). The First Hollow Stem Advisor and the updates we provide give an indication of the FHS stem conditions in a particular area. However, because of the number of factors that can influence when FHS occurs, we cannot stress enough the importance of checking for FHS on a field-by-field basis.

Table 1. First hollow stem (FHS) results by variety collected from non-grazed plots at Stillwater on 2/17/17, 2/21/17, and 2/24/17. Plots were sown on 9/13/16. The threshold target for FHS is 1.5 cm (5/8” or the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements. Varieties that have reached FHS are highlighted in red.

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8” or the diameter of dime) of stem below the developing grain head (full explanation). Wheat stem elongation at our Chickasha location has progressed but not as rapidly as we have observed in other areas. Listed below is the second set of FHS measurements from this location (Table 1). At this time, only 1 wheat variety has reached the 1.5 cm threshold. As a reminder, these measurements were collected from plots under simulated grazing. Grazing delays FHS, which is why we recommend checking plants from a non-grazed area of the field (e.g., just outside the hotwire). This helps provide time for finalizing plans to remove the cattle as the grazed area reaches FHS. For example, our border plots of Ruby Lee, sown at the same time, just reached FHS; whereas, within the plots, Ruby Lee measured 0.5 cm. Keep in mind that several factors in addition to grazing influence the onset of FHS. These include the wheat variety, location, temperature, available moisture, and planting date (later sown wheat will typically reach FHS later). The First Hollow Stem Advisor and the updates we provide give an indication of the FHS stem conditions in a particular area. However, because of the number of factors that can influence when FHS occurs, we cannot stress enough the importance of checking for FHS on a field-by-field basis. 

Table 1. First hollow stem (FHS) results by variety collected at Chickasha on 2/16/17 and 2/22/17. Plots were sown on 9/15/16. The threshold target for FHS is 1.5 cm (5/8” or approximately the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements. Varieties that have reached FHS are highlighted in red.

*triticale variety

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture (full explanation). Wheat growth at our Stillwater location has continued to progress rapidly. Listed below is the second set of FHS measurements from this location (Table 1). These measurements were collected from plots that were not grazed. The point of reference I gave the last post was approximately 50% of the varieties reach or pass FHS by March 1 at Stillwater under normal conditions. Of the 31 wheat varieties we took measurements on today, 20 of those have reached FHS. That brings the total to 51 out of 62 wheat varieties (82%) which have reached FHS. 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. The First Hollow Stem Advisor can provide an estimate of first hollow stem progress in your area.

Table 1. First hollow stem (FHS) results by variety collected at Stillwater on 2/17/17 and 2/21/17. Plots were sown on 9/13/16. The threshold target for FHS is 1.5 cm (approximately the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements. Varieties that have reached FHS are highlighted in red.

This article was written by Dr. Bob Hunger, Extension Wheat Pathologist

Department of Entomology & Plant Pathology

Oklahoma State University – 127 Noble Research Center

405-744-9958

     I indicated last November that leaf rust was severe in many wheat varieties that had been planted early (mid-September) in Dr. David Marburger’s variety demonstration strips here at Stillwater. As we moved into December and January, there were two severe cold spells along with drought that caused significant death of the rank foliage.  Many of the burned/dead leaves were infected with leaf rust, and killing of these infected leaves stopped the spread of leaf rust to new/young foliage.  The burning of the foliage in these plots was quite noticeable in mid-January (Figure 1A).  Last week I examined these plots to see if leaf rust had overwintered, and sure enough, viable leaf rust pustules were present on some of the newer/younger leaves (Figure 1B).

Figure 1. (A) Severe leaf burn of wheat in mid-January, 2017.  (B)  Leaf rust pustules as observed on leaves in mid-February in the same plots in (A).

     Hence, leaf rust has overwintered in much of Oklahoma and inoculum to start this disease in the spring will come not only from within the state, but also from Texas where widespread, moderate levels of leaf rust have been reported (see report below from Texas).  The two recent widespread rain events also will support the further infection and spread of leaf rust in Oklahoma, but weather through March and April still will be the ultimate determiner as to how severe leaf rust becomes in Oklahoma in 2017.  However, be sure to start checking your wheat over the coming weeks for the presence of leaf rust (especially if you have a moderately susceptible to susceptible variety).  I can’t imagine any spraying is needed at this time for leaf rust, but you should stay alert for the presence of this disease as we proceed into March and April when conditions for leaf rust infection and spread typically become more favorable.

     The other rust that can greatly impact yield in Oklahoma is stripe rust (Figure 2). Typically if stripe rust is going to be a problem in Oklahoma we start to see “hot spots” in fields from late February into early March.  Note that often early season stripe rust infections do not typically show the striping pattern associated with stripe rust but rather pustules tend to occur more in clusters as depicted in Figure 3.  Reports of moderate to severe stripe rust also typically are coming in from Texas by this time in years when stripe rust is severe in Oklahoma.  However, no stripe rust has yet been reported in Oklahoma this year, and reports indicate stripe rust is sparse in Texas (see below).  This is good news in terms of the likelihood of stripe rust in Oklahoma, but continue to watch for stripe rust when looking for leaf rust.

Figure 2.  Early season infection of stripe rust.  Note that in contrast to later season stripe rust infection, early season infections do not show the “striping” typically associated with stripe rust.

     Other foliar disease to watch for include tan spot, Septoria leaf blotch, and powdery mildew (Figure 3A-C).  These diseases (especially tan spot and Septoria leaf blotch) are more likely to occur in no-till, continuous wheat fields.  If sufficiently severe in a no-till field, spraying for these in March may be beneficial but only if young wheat plants are severely spotted with one of these diseases.  For additional information regarding early season foliar wheat diseases and possible control with an early fungicide application, please see our fact sheet (PSS-2138) that discusses split application of fungicides by clicking here.

Figure 3. Wheat diseases typically observed in no-till, continuous wheat fields include (A) Tan spot; (B) Septoria leaf blotch; (C) Early season powdery mildew.

Reports/excerpts of reports from other states:

Texas:  Dr. Clark Neely; Assistant Professor & Extension Small Grains and Oilseed Specialist; Texas A&M University; Feb 14, 2017: Weather conditions have been drier this fall and winter than the previous two years, which is having a positive impact on wheat rust presence across the state. This time last year, producers were dealing with widespread reports of stripe rust in their wheat fields due to wet conditions. This year, stripe rust has been reported in a few locations throughout Central and South Texas, however, pressure appears lighter overall and observed mainly in highly susceptible border plots (‘TAM 111’) in research trials. A few reports of very light stripe rust in producer fields in the central Blacklands was reported also. Light pressure was reported in an Ellis County trial and trace amounts were found in trials near Thrall and College Station. No stripe rust has yet been found in South Texas (Uvalde, Castroville, Corpus Christi), Northeast Texas (Greenville), or the Rolling Plains. Though inoculum is currently low, forecasted weather conditions appear to be favorable for further development beginning this weekend through mid-week as a large percentage of the state is expected to receive an inch or more of precipitation and coincide with cooler temperatures. Therefore, producers in the Blacklands should keep an eye on wheat fields over the next couple of weeks to watch for further stripe rust development.

     Meanwhile, leaf rust is present in much of Southeast Texas. Research plots in Thrall, College Station and Wharton all show moderate leaf rust pressure so far. Light levels of leaf rust are also reported in producer fields in Hill and McLennan Counties with a single severe case reported in ‘TAM 304’ that was sprayed with a fungicide. With plenty of inoculum present, this disease is likely to spread once temperatures increase in the coming weeks, though moisture conditions throughout the spring will influence the degree and speed to which it will increase. As of two weeks ago, leaf rust was not observed at Uvalde or the Castroville nursery and recent reports indicate little to no leaf rust further north in Northeast Texas and the Rolling Plains.

Spring-planted oat has been a “go to” forage crop for southern Great Plains beef producers for years. It is a good option when winter wheat was not planted in the fall due to wet conditions, or, as may be the case in certain areas of Oklahoma this year, when wheat failed to emerge due to drought. Forage production potential for spring-planted oat is around 1,500 to 2,00 lb/ac, but you will need about 60 – 75 lb/ac of nitrogen to make this type of yield. A fact sheet detailing spring oat production for hay and grazing can be found by clicking here or going to www.wheat.okstate.edu under “Wheat Management” then “Seeding”. Some of the key points from that fact sheet are listed below:

Spring oat can provide an alternate hay or forage source in the spring.

Seed — Plant 80 – 100 lb/ac of good quality seed that has a germination of no less than 85%. There aren’t many options regarding varieties, so you will likely be limited to whatever seed is available in your area. The key is not to cut back on seeding rate, regardless of variety.

Seedbed — Sow oat seed at approximately 1/2 to 3/4 inches deep. Most producers will be better off with a conventionally-tilled seedbed. You are planting seed at a time of year when the ground is already marginal regarding temperature. Conventionally-tilled seedbeds warm more quickly, which should speed germination. There is one exception to the conventional till recommendation. If you are sowing into a stale seedbed or a failed wheat crop that is very thin, no-till should be okay. Just avoid situations where excessive residue will keep the soil cold.

Grazing — Oat plants should have a minimum of six inches of growth prior to grazing. Unlike fall-seeded cereals, you should not expect a large amount of tillering. A good stand of spring oat can provide a 750 lb animal approximately 60 days of grazing when stocked at 1.5 animals per acre

Hay — Oat should be cut for hay at early heading to maximize yield and quality.

Yesterday, we posted our first hollow stem (FHS) results from Chickasha. None of the varieties had reached FHS, but as I cautioned in that post, those measurements were collected under a simulated grazing scenario based on the way forage data was collected from that trial.

Listed below is the first set of FHS measurements from our Stillwater location (Table 1). These measurements were collected from plots that were not grazed. The point of reference I gave yesterday was approximately 50% of the varieties reach or pass FHS by March 1 at Stillwater under normal conditions. From the results below, 30 of the 62 wheat varieties examined have just reached FHS. Compared to the point of reference, that is about 12 days ahead of schedule.

On February 10, we checked several of the known ‘early’ varieties (e.g., Billings, Gallagher) at Stillwater, and little to no hollow stem was present at the time. Therefore, we thought we would be safe with taking measurements in the middle to latter part of the week. Well, the warm temperatures over that weekend and the rainfall we received at Stillwater earlier this week provided great growing conditions. As a result, about half of the wheat varieties reached FHS. I suspect that we missed being on the front side of the 1.5 cm threshold by about a day or two for a lot of these varieties that have reached FHS. Our next round of measurements from Stillwater will come early next week.

Table 1. First hollow stem (FHS) results by variety collected on 2/17/17 at Stillwater. Plots were sown on 9/13/16. The threshold target for FHS is 1.5 cm (approximately the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements. Varieties that have reached FHS are highlighted in red.

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture (a more detailed explanation can be found by clicking here). Each year, we collect FHS measurements from the varieties in our forage variety trials. This year, we have two forage variety trial locations, Chickasha and Stillwater. Both locations were sown in mid-September. To give you a point of reference, under normal conditions approximately 50% of the varieties reach or pass FHS by March 1^st at Stillwater. However, with the warmer than normal temperatures and estimates from the First Hollow Stem Advisor on the Oklahoma Mesonet, we have begun collecting our FHS measurements.

Listed below are the first set of FHS measurements from our Chickasha location (Table 1). A couple of the ‘early’ varieties are beginning to show hollow stem, but none of the varieties have reached FHS at this time. However, with the recent rainfall and warm forecasted temperatures, I suspect some of the early varieties will reach FHS very soon. I also need to provide you a word of caution with the Chickasha results. Based on how we collected our forage measurements this year, the FHS results at this location are coming from a simulated grazing situation. Grazing can delay the onset of FHS, which is why we recommend checking for FHS from a non-grazed area of the field (e.g., just outside the hot wire) to give a short buffer time for finalizing plans to remove the cattle. Because of this, there may be some varieties on this list if planted in the Chickasha area that may be closer to FHS than what is presented in the table. As always, keep in mind that wheat varieties in areas south of Chickasha may be further along, while varieties in areas further north may be a little behind yet. We are also taking measurements today from our trial at Stillwater, and I will get those results posted as soon as we get them summarized.

Table 1. First hollow stem (FHS) results by variety collected on 2/16/17 at Chickasha. Plots were sown on 9/15/16. The threshold target for FHS is 1.5 cm (approximately the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements.

*triticale variety

First hollow stem (FHS) occurs just prior to the jointing growth stage and is the optimal time to remove cattle from wheat pasture. This is the optimal time because the added cattle weight gains associated with grazing past first hollow stem are not enough to offset the value of the reduced grain yield (1-5% loss every day past FHS). With the warmer than normal temperatures throughout the beginning of this year and the forecasted warm temperatures, it is likely we will start seeing FHS occur for some of our “early FHS” wheat varieties in Oklahoma in the next 7-14 days, especially towards the southern border.

One of the moving targets each year is determining when to start scouting for FHS. To help combat this, the First Hollow Stem Advisor was developed by researchers at Oklahoma State University. This is an online tool available on the Mesonet website, https://www.mesonet.org/index.php/agriculture/category/crop/wheat/hollow_stem_advisor. This tool uses soil temperature data to show the current probability of FHS occurrence, as well as 1-week and 2-week projections (detailed information on how this works can be found here). With this tool, producers can select their variety from a list of varieties that separates them into three FHS categories: early, middle, and late. Then, maps can be generated to provide the probability of FHS based on current conditions and the 1- and 2-week projections. Charts and tables can also be generated for individual Mesonet sites. Created maps have a color scheme to represent the probability of FHS occurrence. When using this tool, it is recommended to start scouting for FHS from a non-grazed part of the field once the 5% probability level is reached (green color). Because stem elongation will begin moving quickly as the temperature warms up, starting your scouting at the 5% level will help give you the time it takes for making the necessary preparations for removing the cattle by the time FHS occurs. Methods on how to scout for FHS are listed at the end of this post. For producers who do not scout, it is recommended to remove cattle when the 50% probability level is reached. A 50% probability level indicates that over a multi-year period (e.g., 10 years), FHS has occurred by that date in 50% of those evaluated years (e.g., 5 years). The same interpretation is used for other probability levels.

To give an example of what the tool provides and show some of the FHS conditions around OK, I have generated some statewide maps below. For producers in areas of southeastern and south central OK who planted an “early” wheat variety (e.g., Gallagher), now would be the time to go out and start scouting for FHS (Figure 1).

Figure 1. Current FHS probabilities for “early” wheat varieties.

Looking at the 1-week projection for “early” varieties, you can see how the probabilities have increased, and producers in areas further north should begin scouting (Figure 2).

Figure 2. One-week FHS projection (i.e., through February 8) for “early” wheat varieties.

For producers who planted “middle” or “late” FHS varieties, the 1-week projections indicate producers across much of the state still have a little bit of time yet before beginning to scout. However, producers along the southern border will need to begin scouting (Figure 3).

Figure 3. One-week FHS projections (i.e., through February 8) for “middle” (top) and “late” (bottom) wheat varieties.

Methods for scouting for FHS:

• Check for FHS in a non-grazed area of the same variety and planting date. Variety can affect FHS date 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 the developing grain head may still be below the soil surface at this stage.
• 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.
• More detailed information on FHS can be found at wheat.okstate.edu under ‘wheat management’ then ‘grazing’ or by clicking here.

The first hollow stem growth stage is reached when there is 1.5 cm of hollow stem (about the diameter of a dime) below the grain head. Photo by Dr. Jeff Edwards.

Similar to previous years, we will monitor occurrence of FHS in our wheat plots at Stillwater and Chickasha and report the findings on this blog.