About Me

Amanda De Oliveira Silva

Amanda De Oliveira Silva

I have served as an Assistant Professor and Small Grains Extension Specialist at Oklahoma State University since August 2019. I believe that close interaction with producers is vital to understand their production strategies and to establish realistic research goals. My program focuses on developing science-based information to improve the agronomic and economic viability of small grains production in Oklahoma and in the Southern Great Plains.

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First Hollow Stem Update – 3/17/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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 a dime) of stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. For an additional resource, see the Mesonet First Hollow Stem Advisor.

We use an accelerated growth system to report the earliest onset of FHS stage. Trials are seeded early to simulate a grazed system, but the forage is not removed. Varieties reported here with the earliest FHS date should be the first to monitor in commercial fields. In practice, wheat that is grazed will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/20 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/20 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red.

  • Additional resources available:

Wheat Disease Update – 15 March 2021

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

Although relatively quiet, some wheat diseases have started to appear across Oklahoma over the last week.  For example, around Stillwater I am starting to observe patches of wheat showing symptoms of the wheat soil-borne mosaic (SB)/wheat spindle streak mosaic (SS) complex.  So far, I have observed these symptoms only in susceptible varieties in Dr. de Silva’s variety demo and in my SB-SS nursery.  These virus diseases are not a problem in Oklahoma or the central plains due to effective and durable genetic resistance in nearly all wheat varieties planted in Oklahoma for the last four decades.  However, planting a variety susceptible to either or both of these virus diseases could be an invitation to having an occurrence of these diseases.  It seems as though only far northwest Oklahoma and the panhandle have environments that limit the occurrence of these two virus diseases.

      In trials around Stillwater towards the end of last week, I found sparse powdery mildew and fairly abundant Septoria/Stagonospora leaf spot on leaves of ‘Ruby Lee’ (Figure 2).  This was in Dr. Brett Carver’s dual purpose observation nursery, which is an early planted nursery.  In no trials did I find either leaf or stripe rust, although Dr. Amanda de Oliveira Silva had found both leaf rust and powdery mildew in her demonstration trial in later January before the hard freeze and snow occurred in early to mid-February.

Figure 1.  Wheat showing reaction to the wheat soil-borne mosaic (WSBM)/wheat spindle streak mosaic (WSSM) complex. Left photo:  Wheat breeder line susceptible (left) and resistant (right) to WSBM. Center photo: Symptoms typical of WSBM.  Right photo:  Symptoms typical of WSSM.

Figure 2. Upper photo are symptoms on a wheat leaf indicative of Septoria or Stagonospora leaf blotch found near Stillwater on 13-Mar-2021.  The lower photo is of a wheat leaf with symptoms indicative of tan spot observed in southwest Oklahoma by Gary Strickland, (County Educator; Jackson County), 3-11-2021.

First Hollow Stem Update – 3/12/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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 a dime) of stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. For an additional resource, see the Mesonet First Hollow Stem Advisor.

We use an accelerated growth system to report the earliest onset of FHS stage. Trials are seeded early to simulate a grazed system, but the forage is not removed. Varieties reported here with the earliest FHS date should be the first to monitor in commercial fields. In practice, wheat that is grazed will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/20 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/20 but not grazed or clipped. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements. Varieties exceeding the threshold are highlighted in red.

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.

  • Additional resources available:

First hollow stem update – 3/9/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. Several wheat varieties in Stillwater and a few in Chickasha have reached or passed the 1.5 cm threshold.

The Mesonet 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, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

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.

  • Additional resources available:

Potential risk of leaf injury from topdressing N this week (too hot and windy!)

Amanda de Oliveira Silva, Small Grains Extension Specialist and Brian Arnall, Precision Nutrient Management Specialist

The forecast indicates hot (~75 F) and windy (~20-30 mph) conditions this week in Oklahoma (Mesonet). If you plan to topdress N to wheat, be aware that there is a high risk of causing leaf burn due to the predicted weather.

When comparing application methods, a stream bar is better than a flat fan for topdressing N in general. A flat fan would burn and even kill the wheat if used this week. However, using a stream bar under 20-30 mph wind is also problematic, as the wind will spread out the stream over the wheat, making it splash over larger areas result in more foliar burn.

Streamer nozzles provide uniform application of UAN in a wide variety of environmental conditions.

What rate can I apply without causing leaf burn from N this week?

There is a high risk of causing leaf burn by applying any rate (20 to 200lbs/ac) of N in the next 2-3 days (March 8-11, 2021). If using streamer nozzles the total amount of leaf damage could be small resulting in no yield loss. In this case, applying N this week may result in streaked fields later, but the wheat should grow out of it if conditions are appropriate. However, as you start to increase coverage (i.e. the amount of leaf burn) there is a threshold at which yield is lost. In cases with flat fan the high N rate will potentially kill the majority above ground biomass and negatively impact yield.

Other options to reduce the potential risk of injury. Wait to topdress N when the weather cools down (if you believe you will be able to get into the field before jointing) or split the N rate between now and sometime before jointing. If you want to apply and are very worried about tissue damage, one option is to dilute the UAN with water. Usually a 50/50 (UAN/H2O) ratio does a good job of reduction impact of the salt in UAN. 

If you have questions, please feel free to reach out to us!

Brain Arnall at b.arnall@okstate.edu

Amanda de Oliveira Silva at silvaa@okstate.edu

First Hollow Stem Update – 3/5/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. A few more wheat varieties in Stillwater have reached or passed the 1.5 cm threshold.

The Mesonet 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, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

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.

  • Additional resources available:

First Hollow Stem Update – 3/2/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. A few more wheat varieties in Stillwater have reached or passed the 1.5 cm threshold.

The Mesonet 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, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

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.

  • Additional resources available:

First Hollow Stem Update – 2/26/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. A few more wheat varieties in Stillwater have reached or passed the 1.5 cm threshold.

The Mesonet 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, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

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.

  • Additional resources available:

First hollow stem update – 02/25/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

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). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The photo shows the first hollow stem in wheat
Figure 1. First hollow stem occurs when hollow stem equivalent to the diameter of a dime (1.5 cm) is present below the developing grain head.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. Few wheat varieties in Stillwater have reached or passed the 1.5 cm threshold.

The Mesonet 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, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

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.

What will these cold temperatures do to the wheat crop?

Amanda de Oliveira Silva, Small Grains Extension Specialist

Weather forecasts indicate that temperatures will continue to drop in the next few days. The extent of possible damage from these below-normal temperatures on wheat will depend on several factors such as wheat developmental stage, soil moisture, snow cover, field conditions, and how cold and for how long these cold weather stays.

Most of the wheat in Oklahoma was dormant or just starting to come out of dormancy before this extreme cold front came in. The more advanced in growth the wheat is, the more exposed the growing point is and susceptible to injury. On the other hand, wheat fields planted late in December are also vulnerable as the wheat may not have had the time to develop its crown roots and tiller to sustain these cold temperatures. The most important part of the plant is the crown at this moment. We may see leaf damage, but if the crown remains alive, the plant can survive. Figure 1 provides a general guide to the minimum temperature threshold and its impact on yield. Keep in mind these temperature thresholds are not exact but provide a decent rule of thumb. Temperatures closer to the soil surface might be higher than those reported by weather stations one meter above the soil surface, especially if moisture is present. 

Figure 1. Temperatures that can cause injury to winter wheat at different growth stages. Source: Kansas State University publication C646: Spring Freeze Injury to Kansas Wheat.

Except for the western OK and Panhandle regions, most areas of the state were with adequate soil moisture, which helps to insulate the crop and improves survival chances. Also, if we receive the snow cover that is forecasted, the wheat will be more protected from the harsh conditions.

Regarding my last post that some varieties may have reached first hollow stem (FHS). Growers should keep in mind that FHS is based on the largest tiller on the plant. Even if we lose the largest tillers, we are fine as long as other tillers are viable and we have favorable growing conditions.

Figure 2. Leaf tips which have turned necrotic due to freezing temperatures. Photo taken in March 2017 courtesy of Josh Bushong, OSU Northwest area Extension agronomist.
Figure 3. More severe freeze damage causing the leaves to turn yellow-white with plants losing their overall turgidity. Source: Kansas State University publication C646: Spring Freeze Injury to Kansas Wheat.

Each freeze event is unique. It will take some time (1-2 weeks after the cold weather passes) to assess the actual impact of the below-normal temperatures on wheat. We will have to keep watching it as it will vary on a field-by-field basis.  

Resources

Contact your local county Extension office.

For additional read refer to:

Assessing Freeze Damage on Wheat

 C646 – Spring Freeze injury to Kansas Wheat