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 hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (Table 2) are listed below. For an additional resource and wheat update on FHS, 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 Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
Amanda de Oliveira Silva, Small Grains Extension Specialist
Areas of Oklahoma with dry conditions have begun to see some visible wheat injury due to brown wheat mite (Figure 1) and winter grain mite (Figure 2). Last week, Josh Bushong, OSU Northcentral Area Extension Agronomist, reported seeing fields with injury due to brown wheat mites in Alfalfa and Kingfisher counties (Figure 3). Later that week Tyler Lynch, the Senior Agriculturalist in the Small Grains Program also reported seeing wheat grain mites in our wheat plots at Alfalfa and Woods Counties.
Two common mites can injure wheat, the brown wheat mite and the winter grain mite. Producers need to remain alert so that they don’t mistake damaged wheat from small grains mites for drought or virus disease.
Figure 1. Brown wheat mite with oversummering egg
Brown wheat mite is small (about the size of this period.) with a metallic brown to black body and four pairs of yellowish legs (Figure 1). The forelegs are distinctly longer than the other three pairs. Brown wheat mites can complete a cycle in as little as 10-14 days. Oklahoma experiences multiple generations of brown wheat mites that usually peak in spring, and the last generation occurs in April. At that time, females produce a whitish egg that will over summer.
Figure 2. Winter grain mite with a kidney-shaped egg
Winter grain mite is small (about 1 mm long) with a dark blue to black body and four pairs of orange-red legs, and a small reddish spot on the top of its abdomen that can be seen under magnification (Figure 2). Winter grain mite eggs are kidney-shaped, and change from clear, to yellow to reddish-orange after several days. They are laid on leaf blades and stems or the roots near the crown. Besides wheat, many grasses serve as host plants, including barley, oats, ryegrass, and fescue. We typically experience two generations each year, a fall generation and a winter generation that cycles out in March.
Figure 3. Field infested with brown wheat mite. Photos taken by Josh Bushong at Kingfisher County on February 21, 2023.
Figure 4. Leaf stippling from brown wheat mite (left) and grain wheat mite (right) feeding. Photo on the right taken by Tyler Lynch at Alfalfa county on April 24, 2023.
Figure 5. Field infested with winter grain mite
Both mites feed by piercing plant cells in the leaf, which results in “stippling” (Figures 4 and 5). The leaves take on a characteristic brown-grayish or cast and could be mistaken for injury due to herbicide. These mites are more likely to cause injury in wheat stressed from lack of moisture or nutrients.
Figure 6. Winter grain mite hiding in residue
Threshold
Brown wheat mites are not light sensitive but are vulnerable to driving rains of more than 0.25 inches, which tend to reduce populations. Winter grain mites are more tolerant of rainfall but are very light sensitive and tend to avoid bright, sunny days and windy days, so adjust your scouting accordingly. It is best to scout for winter grain mites on still, cloudy days or early morning/late evening. On sunny or windy days, they hide under the soil surface (up to a couple of inches) or congregate under dirt clods (Figure 6). Both mites are associated with continuous wheat production. Research suggests that brown wheat mite can be economically treated when there are 25-50 mites per leaf in wheat that is 6-9 inches tall. An alternative estimation is “several hundred” per foot of a row. The best recommendation for winter grain mite is to treat when plants show visible injury, and there are still mites present.
Chemical control
Only a few insecticides include either mite species on their label. Work conducted by Dr. Gerald Wilde at Kansas State evaluated several insecticides for the control of winter grain mites. Of those registered for winter grain mites, the insecticide dimethoate (Dimethoate and other generics) is effective. Other pyrethroid insecticides, lambda-cyhalothrin (Karate, Warrior II, and its generics), gamma-cyhalothrin (Declare) and beta-cyfluthrin (Baythroid and its generics) are also effective for both mites, even if they are not specifically listed on the label.
Additional resources
Contact your County Extension office
For more information on these mites, consult fact sheet EPP-7093 Mites in Small Grains by clicking here. If you find active mite infestations in your field, consult fact sheet CR-7194 Management of Insect and Mite Pests in Small Grainsfor registered insecticides, application rates, and grazing/harvest waiting periods by clicking here.
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 hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (Table 2) are listed below. For an additional resource and wheat update on FHS, see the Mesonet First Hollow Stem Advisor and the latest interview with SUNUP TV.
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 Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
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 hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (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 Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
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 hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (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 Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
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 hollow stem below the developing grain head (see full explanation). The latest FHS results from OSU forage trials in Stillwater (Table 1) and Chickasha (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 Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
Amanda de Oliveira Silva, Small Grains Extension Specialist
The wheat growing season up to this point has been extremely tough. The forage situation has been a kick-in-the-knees again this year. Wheat “dusted in” emerged at least one month later than the ideal time to promote fall forage production. It was challenging to get a stand established with a cool November and limited rainfall since planting. As a result, many producers did not have the chance to graze or are grazing at a lower stocking rate.
If the predicted shower events occur, it could help to improve conditions in some areas. Still, most of Oklahoma, especially western OK, is under an extreme drought and needs significant rain. For the producers who have pasture to graze, leaving some leaf tissue after grazing will be important for having any chance of a decent grain crop. Ideally, there should be a minimum of 60% canopy coverage (measured from the Canopeo app) left to allow the crop to recover from grazing (PSS-2170). An additional two weeks of grazing past first hollow stem, when conditions are not ideal for plant regrowth and canopy recovery, could reduce wheat yield by approximately 60% relative to its potential (Figure 1).
Figure 1. Grazing past first hollow stem has been shown to reduce grain yield by as much as five percent per day or as little as one percent per day. Factors such as variety, grazing intensity, and environmental conditions will determine the actual yield penalty for grazing past first hollow stem. This figure shows the anticipated yield loss for grazing past first hollow stem given favorable (solid line), unfavorable (dashed line) and average (dotted line) conditions for wheat regrowth following grazing termination (PSS-2147).
The first hollow stem stage (FHS) indicates the beginning of stem elongation or just before the jointing stage. It is a good indicator of when producers should remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8”, or the diameter of a dime) of hollow stem below the developing grain head (Figure 2). This is the optimal period because it gives enough time for the crop to recover from grazing and rebuild the canopy. Also, the added cattle weight gains associated with grazing past the FHS are not enough to offset the value of the potential reduced grain yield (1-5% every day past FHS) (Figure 1). The wheat variety, severity of grazing, time when cattle are removed, and weather conditions after cattle removal determine how much grain yield potential might be reduced.
Figure 2. 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.
Mesonet First Hollow Stem Advisor
Researchers at Oklahoma State University developed the Mesonet First Hollow Stem Advisor to help predict when FHS is nearing. This online tool uses soil temperature data to show the current probability of FHS occurrence and 1-week and 2-week projections. 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 is reached (green color). Because stem elongation will begin moving quickly as the air temperature rises, starting your scouting at the 5% level will help give you the time it takes to make the cattle removal preparations by the time FHS occurs. We listed methods for scouting for FHS at the end of this post. For producers who do not want to scout, it is recommended to remove cattle when the 50% probability level is reached. A 50% probability level indicates that over an evaluated period (e.g., 10 years), FHS would have occurred by that date in 50% of those years (e.g., 5 years). The same interpretation is used for other probability levels.
I have generated some statewide maps below to give an example of what the tool provides and show some of the FHS conditions around Oklahoma. For producers along the southern Oklahoma border who planted an “early” wheat variety (e.g., Gallagher), now would be past the time to remove cattle from the field (Figure 3).
Figure 3. Current FHS probabilities for “early” wheat varieties.Figure 4. One-week FHS projection (i.e., through February 14) for “early” wheat varieties.
Remember that this tool should be used as a proxy to begin scouting for FHS. The best estimate of FHS is still to split stems from plants in each field to determine how developed they are. Another word of caution I want to mention when using the tool for this year is to consider when you finally got stand establishment. If this did not occur until the end of September to the beginning of October (which are most of the cases in Oklahoma this year), this tool might be ahead of where your plants are developmentally. In this case, the tool can still cue you to start scouting. Checking for FHS in each field will let you know if you do have some grazing time left.
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, 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.
If there is 1.5 cm (~5/8″) of hollow stem present, it is time to remove cattle. 1.5 cm is about the same as the diameter of a dime (see picture below).
Find detailed information on FHS and grazing by clicking here.
OSU Small Grains Program is monitoring FHS occurrence on a twice-per-week basis
Similar to previous years, we will monitor FHS occurrence in our wheat plots at Stillwater and Chickasha and report the findings on this blog. Remember that we use an accelerated growth system to report the earliest onset of the 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, grazed wheat will likely reach FHS stage later than reported here, and differences between varieties will likely moderate.
The latest FHS results for each variety planted in our forage trial at Stillwater and Chickasha are listed below (Tables 1 and 2). Most varieties are not near FHS (values well below 1.5 cm). However, values will likely move quickly with a bit of moisture and warmer conditions in the coming weeks in Oklahoma.
Table 1. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 10/06/22 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 Chickasha. Plots were planted on 10/07/22 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.
Contact your local Extension office and us if you have questions.
Acknowledgments:
Tyler Lynch, Senior Agriculturalist
Israel Molina Cyrineu, Graduate Research Assistant
WORLD OF WHEAT 