Bird Cherry Oat Aphid Activity in Southwest Oklahoma

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Ashleigh Faris, Cropping Systems Extension Entomologist & IPM Coordinator
Maxwell Smith, Cotton IPM Specialist

Reports from southwest Oklahoma indicate Bird Cherry Oat Aphid (BCOA) infestations in winter wheat. While these aphids are often present in Oklahoma wheat every year, heavy infestations—especially during the grain-fill stages or in fields intended for grazing—can lead to economic loss through direct feeding and the transmission of viral diseases.

Identification and Differentiation from Other Small Grain Aphids

The Bird Cherry Oat Aphid is relatively easy to identify if you know what to look for, but it can be confused with the Rice Root Aphid (RRA).

  • Bird Cherry Oat Aphid (BCOA), Rhopalosiphum padi:
    • Appearance: Small, pear-shaped, olive-green to greenish-black bodies. Tips of legs are black. “Old” aphids found in winter and early spring often are black but will give birth to more typically colored aphids in the spring.
    • Key Feature: A distinctive reddish-orange or “rusty” patch at the rear of the abdomen, specifically surrounding the base of the cornicles (tailpipes) (Figure 1).
    • Location: Primarily found on the leaves and stems in the lower to middle canopy and can be found throughout the wheat growing season. When in high numbers, feeding can result in honeydew.
  • Rice Root Aphid (RRA), Rhopalosiphum rufiabdominale:
    • Appearance: Very similar in color and possesses a reddish-orange patch.
    • Key Differences: The RRA has a hairy appearance with long & prominent hairs on its antennae and body (Figure 2)
    • Location: As the name suggests, RRA is typically found at or below the soil line on the roots or the very base of the crown. BCOA will stay on the green tissue above ground. RRA typically appear in the fall, soon after wheat emerges.
Figure 1. Bird cherry oat aphid (BCOA) adults and nymphs. Image courtesy of iNaturalist.
Figure 2. Rice root aphid (RRA) adults can appear similar to BCOA. RRA are rarely economically damaging. Image courtesy Rick Grantham, OSU.

BCOA Biology

In Oklahoma and the southern Great Plains, BCOA populations consist entirely of females that give birth to live young (parthenogenesis). This allows for extremely rapid population growth when temperatures are mild. They can survive the winter as active nymphs and adults in the wheat canopy, though their development slows during extreme cold. As the wheat matures or populations become crowded, winged alates are produced to migrate to other fields.

BCOA Damage: Feeding and Disease

The impact of BCOA is twofold:

  1. Direct Feeding Damage: BCOA are sapsuckers. Large numbers can cause leaf yellowing and stunting (Figure 3). In grazing systems, BCOA feeding can interfere with protein assimilation in the plant, potentially reducing the nutritional quality of the forage for cattle.
  2. Viral Transmission: BCOA is a primary vector for Barley Yellow Dwarf Virus (BYDV).
    • Symptoms: Infected wheat displays brilliant yellow or reddish-purple leaf tips. Plants infected in the fall are often severely stunted and have significantly reduced root systems, leading to high yield loss (Figure 3). Spring infections are usually less severe but still impact test weights.
Figure 3. Heavy bird cherry oat aphid (BCOA) with honeydew accumulation and chlorosis/stunting. Image courtesy Angus Catchot, Mississippi State Extension.

Scouting Techniques
Because BCOA often hides in the lower canopy or in the “whorl” of the plant, thorough scouting is essential.
Method: Examine 25 randomly selected tillers across a zigzag transect of the field.
Focus: Look closely at the underside of leaves and inside the leaf sheaths.
Threshold: While wheat can tolerate a surprising number of BCOA, treatment is generally recommended if populations reach 20 to 50 aphids per tiller during the seedling to boot stages. If the wheat is under moisture stress or if the goal is to prevent BYDV spread in early spring, use the lower end of the threshold.
 
Management Recommendations
Natural Enemies: Before spraying, check for the “Three L’s”: Lady beetles, Lacewings, and Lysiphlebus (parasitic wasps). If you see aphid mummies, bloated, tan/bronze-colored aphid husks (Figure 4), the wasps are actively working. If natural enemy populations are high, they can often crash an aphid population without the need for chemicals. Based on recent observations, natural enemy numbers appear be on the low end this year.
Chemical Control: Several insecticides are labeled for BCOA in wheat (Table 1). Organophosphates or pyrethroids are generally effective but be mindful of the flare risk: sometimes spraying for aphids can kill natural enemies and lead to a secondary surge of other pests like mites. We are having widespread reports of brown wheat mites across Oklahoma. BCOA can be spot sprayed with a ground-sprayer.
Before spraying any insecticides consider the return on investment:
Estimate yield loss: Calculate the average number of aphids per tiller from your scouting ( = # aphids/# tillers).
Estimate crop value: Crop Value = Yield Potential X Price per Bushel
Estimate control costs: Control Cost = Insecticide Cost + Application Cost
Estimate preventable loss: Crop Value X Yield Loss from Aphid (0.07)
Approximately 5-9% yield loss occurs when there are 20-40 BCOA per tiller, making average yield loss from BCOA to be 7% or 0.07.
If preventable loss is greater than control costs, then treat!
Cultural Control: For future seasons, delaying planting can reduce the window for fall BCOA migration and subsequent BYDV infection.

Figure 4. Bird cherry oat aphid (BCOA) and brown mummy. These mummies are a result of an aphid being parasitized by Lysiphlebus testceipes wasps.

Table 1. Some foliar insecticides for bird cherry-oat aphid (BCOA) in wheat. The mention, listing, or use of specific insecticides is not an endorsement of that product, nor is it a criticism of similar products not mentioned.

Always follow pesticide label directions, application sites, and rates. Be sure to read and follow the label for preharvest intervals (PHI) and restricted-entry intervals (REI). Use a minimum of 10 GPA by ground and 3 GPA by air (if labelled for aerial application) to ensure adequate coverage.

For assistance with aphid identification or treatment decisions, see OSU Fact Sheet EPP-7099 Small Grain Aphids in Oklahoma and Their Management, or contact your local OSU Extension office.

Brown Wheat Mite Activity in North Central Oklahoma

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Ashleigh Faris, Cropping Systems Entomologist, IPM Coordinator

Following a period of dry weather, wheat growers in central Oklahoma are reporting activity of the Brown Wheat Mite (BWM). Unlike many other wheat pests, BWM thrives in drought conditions, and its damage can often be mistaken for moisture stress or nutrient deficiency.

Identification

The Brown Wheat Mite is small—about the size of a needle point—but is generally easier to spot than the Wheat Curl Mite because it is active on the leaf surface.

  • Appearance: BWM has a dark red to brownish-black, oval-shaped body (Figure 1).
  • Distinguishing Feature: Its front legs are significantly longer than its other three pairs of legs.
  • Behavior: They are most active during the day, particularly in the afternoon, and will quickly drop to the ground if the plant is disturbed (Figure 2).
Figure 1. Brown wheat mite (BWM).
Figure 2. Brown wheat mites (BWM) on wheat. Image courtesy L. Galvin, OSU Extension.

Biology and Life Cycle

BWM populations consist entirely of females that produce offspring without mating (parthenogenesis), allowing for extremely rapid population growth under dry conditions. The BWM has a unique life cycle in that it can lay two types of eggs. Environmental conditions dictate when these two types of eggs are laid:

  • Red Eggs: Laid during the growing season and hatch in about a week when conditions are favorable.
  • White (Diapause) Eggs: Laid as temperatures rise and the crop matures. They are highly resistant and allow the population to survive the summer heat, hatching only when cooler, wetter weather arrives in the fall.

Damage

BWM damage is caused by the mites piercing plant cells and sucking out the plant nutrients.

  • Symptoms: Initial damage appears as “stippling” (fine white or yellow spots) on the leaves. As feeding continues, leaves take on a silvery or bronzed appearance (Figure 3).
  • Tipping: Heavy infestations cause the tips of the leaves to turn brown and die.
  • Weather Interaction: Damage is most severe when plants are already under drought stress. Because both BWM damage and drought cause yellowing/browning, it is essential to confirm the presence of mites before treating.
Figure 3. Brown wheat mite (BWM) damage

Scouting

Because BWM is highly mobile and drops when disturbed, careful scouting is required:

  • Timing: Scout during the warmest part of the day when mites are most active on the upper leaves.
  • The Paper Test: Gently but quickly shake or tap wheat plants over a white piece of paper or a white clipboard. Look for tiny dark specks moving across the surface.
  • Economic Threshold: While thresholds vary based on crop value and moisture stress, research suggests a treatment threshold of 25 to 50 brown wheat mites per leaf in wheat that is 6 inches to 9 inches tall is economically warranted. An alternative estimation is “several hundred” per foot of row. If the wheat is severely stressed, the lower end of that threshold should be used.

Management Recommendations

  • The “Rain” Factor: A significant, driving rain is often the most effective control for BWM. Rain can physically knock mites from the plant and promote fungal pathogens that naturally reduce the population.
  • Chemical Control: If populations exceed the threshold and no rain is in the forecast, chemical intervention may be necessary. Know the cost of the treatment and value of your wheat so you can determine if an application is a worth return on investment.
    • Effective Ingredients: Organophosphates (such as Dimethoate) have historically provided better control than many pyrethroids, as the latter can sometimes result in mite “flaring” or simply fail to provide adequate residual control.
    • Coverage: High water volume is critical to ensure the insecticide reaches the mites, especially if they have moved toward the base of the plant.
    • Pre-harvest Intervals & Grazing Restrictions: Always read and follow the label guidelines. For more on acaricides that can be applied in wheat see the Oklahoma State University Fact Sheet “Management of Insect and Mite Pests in Small Grains” (CR-7194).
  • Cultural Practices: Since BWM thrives in dry, dusty conditions, maintaining good soil moisture and vigorous plant growth can help the crop tolerate feeding. Here’s to hoping for some rain soon in the forecast; we could really use it for lots of reasons in Oklahoma.

Freeze Event Across Oklahoma: What Wheat Growers Should Look For in the Next Few Days

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Temperatures dropped below freezing across parts of the state. Here is how growth stage, temperature, and duration of the freeze influence potential wheat injury.

Amanda de Oliveira Silva, Small Grains Extension Specialist

Several areas across Oklahoma experienced freezing temperatures overnight, with some locations recording multiple hours below freezing (Figures 1 and 2). There is potential for freeze injury, especially in drought-stressed wheat that has reached jointing or later growth stages. If wheat is still before jointing, the growing point remains below the soil surface and is more protected from freezing injury.

However, with the warm conditions we experienced earlier this spring, the crop is running slightly ahead of schedule, and some fields have already reached or passed the jointing stage. At this stage, the developing head has started to move up the elongating stem and is no longer protected.

In the coming days we may start to see additional symptoms of freeze injury. The extent of the injury will depend on several factors, including the growth stage of the plants, how low the temperature dropped, and how long temperatures remained at those levels. Brief freezes often cause little damage, but several hours below critical temperatures during jointing or reproductive stages can reduce yield (Figure 3).

Figure 1. Minimum air temperature (in Fahrenheit) over the past 24 hours at each Mesonet station. Figure courtesy Oklahoma Mesonet.
Figure 2. Number of hours spent at or below freezing (32°F) over the past 48 hours at Mesonet station. Figure courtesy Oklahoma Mesonet.

What are the temperatures that can damage the wheat plants?

The potential for freeze injury depends largely on the growth stage of the crop. Anecdotal evidence sometimes suggests varietal differences in resistance to spring freeze injury, but this is often due to differences in plant maturity at the time of the freeze event. Earlier-maturing varieties are more likely to be injured during spring freezes simply because they are typically more advanced in development.

The susceptibility of wheat plants to freeze injury steadily increases as the crop progresses from jointing to heading and flowering.

Figure 3 below provides a general guide to temperature thresholds and their potential impact on yield. Keep in mind that these values are not exact, but they serve as useful rules of thumb.

Temperatures closer to the soil surface may be slightly higher than those recorded by weather stations located about one meter above the ground, especially when soil moisture is present. Because each freeze event is unique, it is difficult to define exact thresholds. For example, a field at the jointing stage exposed to 24°F for two hours may experience similar injury to wheat exposed to 28°F for a longer period of time.

Figure 3. Temperatures that can cause injury to winter wheat at different growth stages. Source: Kansas State University publication C646: Spring Freeze Injury to Kansas Wheat.

How long should I wait to assess the injury?

Patience is important when evaluating freeze damage. The full extent of injury is usually not visible within the first day or two after the freeze event.

If warm temperatures return quickly, symptoms may become evident within 5–7 days. If temperatures remain cool, it may take 10–14 days before the extent of the injury can be properly assessed.

What freeze injury symptoms should I look for?

One common symptom is leaf tip burn, where leaf tips turn yellow and necrotic (Figure 4). This type of damage is often cosmetic and may not significantly affect yield.

More severe freeze damage may cause entire leaves to turn yellow or white, and plants may lose their turgidity and appear flaccid (Figure 5). In some cases, a “silage” smell may be noticeable several days after the freeze event.

Figure 4. Leaf tips that have turned necrotic due to freezing temperatures. Photo taken in March 2017 courtesy of Josh Bushong, OSU Northwest Area Extension Agronomist.
Figure 5. More severe freeze damage causing leaves to turn yellow-white and plants to lose turgidity. Source: Kansas State University publication C646: Spring Freeze Injury to Kansas Wheat.

The most important plant part to check: the developing head (growing point)

This is particularly important in areas where fields are more advanced in growth. Plants may appear healthy overall while the developing head has been damaged or killed.

To examine the growing point, carefully slice the stem lengthwise. A healthy growing point will have a firm, whitish-green appearance and remain turgid (Figures 6 and 7, left). Often you can lightly flick the head; if it bounces back and does not break, it is likely still healthy.

If the growing point is mushy, limp, breaks easily, or appears brown, it has likely been compromised (Figure 7, right). Another indication of damage is when the next emerging leaf becomes necrotic and lower stems appear discolored with lesions or enlarged nodes.

Figure 6. Close up of a healthy wheat head (growing point) above the second node showing  whitish-green color and turgidity.
Figure 7. Plants that appear healthy may still have damaged heads. The photo on the left shows a healthy head, while the photo on the right shows a freeze-damaged head.

Freeze injury at later growth stages

Freezing temperatures at the boot stage may cause the head to become trapped in the flag leaf sheath, preventing proper head emergence (Figure 8). Whitish awn tips are often an indication that the head was exposed to freezing temperatures and that the flower parts may have been damaged.

Freezes during flowering may cause sterility due to damage to the anthers (the male reproductive organ), resulting in poor kernel set and yield losses (Figure 9).

Figure 8. Freeze injury at the boot stage may cause heads to remain trapped in the boot.
Figure 9. Freeze during flowering may cause sterility due to damage to the anthers, resulting in poor kernel set and yield loss.

Can wheat recover from freeze injury?

The percentage of damaged heads does not always translate directly into yield loss. At the jointing stage, wheat still has the potential to produce additional tillers or retain secondary tillers.

Whether these tillers can compensate for damaged primary tillers will depend on subsequent weather conditions. If growing conditions are favorable, late-emerging tillers may still produce grain. However, if the crop is already near flowering or later stages, recovery becomes much more limited.

Key points to keep in mind

• Every freeze event is unique. Injury must be evaluated on a field-by-field basis. Temperature thresholds are guidelines, not exact predictors of damage. In some cases, conditions may suggest severe injury but fields recover with minimal impact.

• The extent of injury depends on several factors, including growth stage, minimum temperature reached, and duration of freezing temperatures. Field conditions such as elevation, residue cover, and soil moisture can also influence canopy temperatures.

• Symptoms may take several days to appear. Damage may become noticeable over the next days or into the middle of next week. Healthy wheat heads will remain firm and green, while damaged heads may appear bleached, yellow, or brown and break easily when pressed.

Stay Connected!

Enroll in the OSU Wheat text update service by texting the word “wheat” to (855) 452-0486 to receive timely information throughout the wheat season.

If you start to observe freeze injury in your fields over the next several days, send us a text and let us know what you are seeing.

Additional Resources

Contact your local Extension office.

C646: Spring Freeze Injury to Kansas Wheat.

Check Your Wheat: Greenbugs Reported in Central Oklahoma

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Ashleigh M. Faris, Cropping Systems Extension Entomologist

Wheat producers in central Oklahoma are reporting the presence of the greenbug,Schizaphis graminum, in winter wheat fields. Greenbugs are one of the most important insect pests of wheat in the southern Great Plains and can occur from fall through spring. These aphids feed on plant sap and inject toxins into wheat plants, causing characteristic leaf discoloration and plant injury.

Early detection through field scouting is essential to determine whether populations are increasing and if an insecticide treatment is justified.

Greenbug Identification & Biology

Key identifying characteristics of greenbug (Figure 1):

  • Small aphids (~1/16 inch long)
  • Pale to lime-green body
  • Dark green stripe down the middle of the back
  • Dark tips on antennae and legs
  • Found in colonies on the underside of wheat leaves
Figure 1. Greenbug nymphs and adults on wheat leaf. Greenbugs are distinguishable from other aphids based on their lime green bodies, dark green stripe down back, dark antennae, and dark leg tips. Image courtesy of https://databases.nbair.res.in/.

Greenbugs reproduce rapidly under favorable conditions (between 55° F and 95° F) and often occur in patches within fields rather than evenly distributed populations. During periods of cool weather, the greenbug may increase to enormous numbers, due to the absence of natural enemies, which develop significantly slower compared to greenbugs at such temperatures. On the other hand, cold weather can also influence aphid populations. However, this latest cold snap is not enough to eliminate greenbugs. It takes average temperatures below 20° F for at least a week to kill a substantial number of greenbugs in wheat.

Greenbug Damage in Wheat

Greenbugs damage wheat in two ways, through direct feeding and injection of toxic saliva. Greenbugs may also transmit barley yellow dwarf virus (BYDV), which can further reduce yield potential.

Typical early symptoms include small, reddish or copper spots on leaves (Figure 2) and yellowing around feeding sites. Advanced infestations will result in leaves turning yellow or orange, dead leaf tissue, stunted plants, and expanding patches of dead wheat. Heavy infestations may kill seedlings and reduce tillering, particularly during drought stress.

Figure 2. Early damage to wheat caused by greenbugs appears as yellow to reddish, coppery spots. Image courtesy of Alton Sparks, Kansas State Extension.

How to Scout for Greenbugs

The Glance-N-Go™ sampling system developed by Oklahoma State University can help determine whether aphid populations exceed economic thresholds. Download the Greenbug Glance N’ Go Sampler app for your smartphone. You will then input the control cost ($/Acre), crop value ($/Acre), and the Spring sampling window. Use a zig-zag or W-pattern (Figure 3) to scout your field, checking undersides of leaves at three tillers per stop for greenbugs and brown mummies. Use the app to record the numbers of these insects and sample until the app tells you to stop sampling or tells you treat. As temperatures warm, continue to scout regularly as greenbug populations may build.

Figure 3. Scouting pattern for greenbug. Walk a W-pattern across the field and examine plants at multiple locations. Inspect the underside of leaves and base of tillers for aphids and beneficial insects. Image courtesy of A.M. Faris, Oklahoma State University Extension.

Scouting recommendations without the Greenbug Glance N’ Go Sampler app:

  1. Walk a W or zigzag pattern across the field.
  2. Examine 10–20 plants at each stop.
  3. Check:
    • Underside of leaves
    • Leaf midrib
    • Base of tillers
  4. Record:
    • Aphids per tiller
    • Presence of aphid mummies (Figure 4)
    • Beneficial insects

Beneficial Insects

Natural enemies frequently control aphid populations. While scouting for greenbug you should also look for lady beetles, lacewing larvae, hoverfly larvae, and parasitized aphids (“mummies”) (Figure 4). If beneficial insects are abundant, aphid populations may decline without insecticide treatment. Where there are one to two lady beetles (adults and larvae) per foot of row, or 15 to 20 percent of the greenbugs have been parasitized, control measures could be delayed until it is determined whether the greenbug population is continuing to increase.

Based on current wheat scouting, it appears that parasitoid numbers are low this 2026 season so continuing to scout for greenbug will be critical in responding to populations that go unchecked by beneficials.

Figure 4. Brown mummy amongst greenbugs. The brown, inflated insect in the top let of the image is a greenbug that has been parasitized. Look for these mummies when making management decisions. Image courtesy of David Voegtlin, University of Illinois.

Economic Threshold Guidelines

The simplest way to determine if action needs to be taken against greenbugs is to utilize the Glance-N-Go™ sampling system developed by Oklahoma State University. Approximate guidelines historically used in Oklahoma wheat can be found in Table 1 below.

Table 1. Approximate guidelines historically used in Oklahoma wheat for greenbug.

Wheat Growth Stage# Greenbugs per Linear Foot
Seedling wheat50
3–6-inch wheat, 3 tillers or more100 – 300
Late vegetative wheat300 to 500

Thresholds are influenced by:

  • Wheat growth stage
  • Crop value
  • Cost of treatment
  • Presence of beneficial insects

Insecticides Labeled for Greenbugs in Wheat

Aphid feeding and insecticide performance are strongly influenced by temperature. Greenbugs tend to move higher on wheat plants during warm conditions but may move lower on the plant or below ground during cold weather, reducing exposure to insecticides. As a result, damaging populations are most often observed in late winter and early spring. Insecticides generally perform best when temperatures are above 50°F, and control may occur more slowly in cooler conditions (e.g., control at 45° F may take roughly twice as long as at 70° F). If applications must be made under cooler temperatures, use the highest labeled rate. Wheat grown under irrigation can typically tolerate higher greenbug populations than dryland wheat.

Table 2. Common foliar options for greenbug in winter wheat.

Active IngredientExample Trade Names
Dimethoate*Dimethoate 4E
Chlorantraniliprole + Lambda-cyhalothrinBeseige*
Lambda-cyhalothrinWarrior II*
Gamma-cyhalothrinProaxis*, Declare
Zeta-cypermethrinMustang Maxx
SulfoxaflorTransform WG
FlupyradifuroneSivanto Prime
*Greenbug is known to have many biotypes. Besiege and Proaxis Insecticides may provide suppression only. Use the maximum rate when treating greenbug.

Always follow pesticide label directions, application sites, and rates. Be sure to read and follow the label for preharvest intervals (PHI) and restricted-entry intervals (REI). Use a minimum of 10 GPA by ground and 3 GPA by air (if labelled for aerial application) to ensure adequate coverage.

For assistance with aphid identification or treatment decisions, see OSU Fact Sheet EPP-7099 Small Grain Aphids in Oklahoma and Their Management, or contact your local OSU Extension office.

First Hollow Stem Update – 3/13/2026

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Amanda de Oliveira Silva, Small Grains Extension Specialist

The first hollow stem stage 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 (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. 

OSU Small Grains Program monitors FHS occurrence on a twice-per-week basis

As in previous years, we will continue monitoring FHS occurrence in our wheat plots at Stillwater and Chickasha and share updates on this blog. In past years, our forage trials—where FHS samples are collected—were seeded early to simulate a grazed system, though forage was not removed. This method created an accelerated growth environment, allowing us to identify the earliest onset of FHS. Varieties that reach FHS earliest in these trials should be closely monitored in commercial fields.

This year, we are continuing with a new approach by simulating grazing with a mower in the forage trial in Stillwater. This will allow us to compare whether varieties reach FHS at different times when grazed versus non-grazed. We hypothesize that the simulated grazing treatment will likely delay FHS relative to the non-grazed treatment, with FHS differences among varieties becoming less pronounced. We also hypothesize that the amount of delay will vary among varieties, such that an early-FHS variety in the non-grazed environment may appear more intermediate in its FHS arrival with canopy removal. This comparison will provide insight into how canopy removal from grazing impacts the timing of reproductive development.

The latest FHS results for each variety planted in our forage trials at Stillwater and Chickasha are summarized below (Tables 1 and 2). All varieties have reached the 1.5 cm FHS threshold.

Table 1. First Hollow Stem (FHS) results for each wheat variety collected at Stillwater. Plots were planted on 10/10/2025, with one section left unclipped and the other clipped to simulate grazing. The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red. For the simulated grazing, plots were mowed on January 2nd and 13th, and on February 9th and 16th at a 3” cutting height, with the frequency representing a light grazing treatment.

Table 2. First Hollow Stem (FHS) results for each wheat variety collected at Chickasha. Plots were planted on 9/25/2025, with all sections left unclipped (i.e., not grazed). The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red.

Contact your local Extension office and us if you have questions. 

Additional resources available:

Acknowledgments: 

Tyler Lynch, Senior Agriculturalist

Francisco H. Aispuro Arana, Graduate Research Assistant

Israel Molina Cyrineu, Graduate Research Assistant

Yanina Correndo, Graduate Research Assistant

Juan Bautista Bruno, Visiting scholar

Ana Sarah Silveira Barbosa, Visiting scholar

First Hollow Stem Update – 3/5/2026

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Amanda de Oliveira Silva, Small Grains Extension Specialist

The first hollow stem stage 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 (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. 

OSU Small Grains Program monitors FHS occurrence on a twice-per-week basis

As in previous years, we will continue monitoring FHS occurrence in our wheat plots at Stillwater and Chickasha and share updates on this blog. In past years, our forage trials—where FHS samples are collected—were seeded early to simulate a grazed system, though forage was not removed. This method created an accelerated growth environment, allowing us to identify the earliest onset of FHS. Varieties that reach FHS earliest in these trials should be closely monitored in commercial fields.

This year, we are continuing with a new approach by simulating grazing with a mower in the forage trial in Stillwater. This will allow us to compare whether varieties reach FHS at different times when grazed versus non-grazed. We hypothesize that the simulated grazing treatment will likely delay FHS relative to the non-grazed treatment, with FHS differences among varieties becoming less pronounced. We also hypothesize that the amount of delay will vary among varieties, such that an early-FHS variety in the non-grazed environment may appear more intermediate in its FHS arrival with canopy removal. This comparison will provide insight into how canopy removal from grazing impacts the timing of reproductive development.

The latest FHS results for each variety planted in our forage trials at Stillwater and Chickasha are summarized below (Tables 1 and 2). Most varieties have reached the 1.5 cm FHS threshold.

Table 1. First Hollow Stem (FHS) results for each wheat variety collected at Stillwater. Plots were planted on 10/10/2025, with one section left unclipped and the other clipped to simulate grazing. The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red. For the simulated grazing, plots were mowed on January 2nd and 13th, and on February 9th and 16th at a 3” cutting height, with the frequency representing a light grazing treatment.

Table 2. First Hollow Stem (FHS) results for each wheat variety collected at Chickasha. Plots were planted on 9/25/2025, with all sections left unclipped (i.e., not grazed). The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red.

Contact your local Extension office and us if you have questions. 

Additional resources available:

Acknowledgments: 

Tyler Lynch, Senior Agriculturalist

Francisco H. Aispuro Arana, Graduate Research Assistant

Israel Molina Cyrineu, Graduate Research Assistant

Yanina Correndo, Graduate Research Assistant

Juan Bautista Bruno, Visiting scholar

Ana Sarah Silveira Barbosa, Visiting scholar

First Hollow Stem Update – 3/2/2026

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Amanda de Oliveira Silva, Small Grains Extension Specialist

The first hollow stem stage 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 (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. 

OSU Small Grains Program monitors FHS occurrence on a twice-per-week basis

As in previous years, we will continue monitoring FHS occurrence in our wheat plots at Stillwater and Chickasha and share updates on this blog. In past years, our forage trials—where FHS samples are collected—were seeded early to simulate a grazed system, though forage was not removed. This method created an accelerated growth environment, allowing us to identify the earliest onset of FHS. Varieties that reach FHS earliest in these trials should be closely monitored in commercial fields.

This year, we are continuing with a new approach by simulating grazing with a mower in the forage trial in Stillwater. This will allow us to compare whether varieties reach FHS at different times when grazed versus non-grazed. We hypothesize that the simulated grazing treatment will likely delay FHS relative to the non-grazed treatment, with FHS differences among varieties becoming less pronounced. We also hypothesize that the amount of delay will vary among varieties, such that an early-FHS variety in the non-grazed environment may appear more intermediate in its FHS arrival with canopy removal. This comparison will provide insight into how canopy removal from grazing impacts the timing of reproductive development.

The latest FHS results for each variety planted in our forage trials at Stillwater and Chickasha are summarized below (Tables 1 and 2). Some varieties have reached the 1.5 cm FHS threshold.

Table 1. First Hollow Stem (FHS) results for each wheat variety collected at Stillwater. Plots were planted on 10/10/2025, with one section left unclipped and the other clipped to simulate grazing. The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red. For the simulated grazing, plots were mowed on January 2nd and 13th, and on February 9th and 16th at a 3” cutting height, with the frequency representing a light grazing treatment.

 Table 2. First Hollow Stem (FHS) results for each wheat variety collected at Chickasha. Plots were planted on 9/25/2025, with all sections left unclipped (i.e., not grazed). The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red.

Contact your local Extension office and us if you have questions. 

Additional resources available:

Acknowledgments: 

Tyler Lynch, Senior Agriculturalist

Francisco H. Aispuro Arana, Graduate Research Assistant

Israel Molina Cyrineu, Graduate Research Assistant

Yanina Correndo, Graduate Research Assistant

Juan Bautista Bruno, Visiting scholar

Ana Sarah Silveira Barbosa, Visiting scholar

First Hollow Stem Update – 2/17/2026

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Amanda de Oliveira Silva, Small Grains Extension Specialist

The first hollow stem stage 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 (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. 

OSU Small Grains Program monitors FHS occurrence on a twice-per-week basis

As in previous years, we will continue monitoring FHS occurrence in our wheat plots at Stillwater and Chickasha and share updates on this blog. In past years, our forage trials—where FHS samples are collected—were seeded early to simulate a grazed system, though forage was not removed. This method created an accelerated growth environment, allowing us to identify the earliest onset of FHS. Varieties that reach FHS earliest in these trials should be closely monitored in commercial fields.

This year, we are continuing with a new approach by simulating grazing with a mower in the forage trial in Stillwater. This will allow us to compare whether varieties reach FHS at different times when grazed versus non-grazed. We hypothesize that the simulated grazing treatment will likely delay FHS relative to the non-grazed treatment, with FHS differences among varieties becoming less pronounced. We also hypothesize that the amount of delay will vary among varieties, such that an early-FHS variety in the non-grazed environment may appear more intermediate in its FHS arrival with canopy removal. This comparison will provide insight into how canopy removal from grazing impacts the timing of reproductive development.

The latest FHS results for each variety planted in our forage trials at Stillwater and Chickasha are summarized below (Tables 1 and 2). Most varieties are still well below the 1.5 cm FHS threshold.

Table 1. First Hollow Stem (FHS) results for each wheat variety collected at Stillwater. Plots were planted on 10/10/2025, with one section left unclipped and the other clipped to simulate grazing. The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red. For the simulated grazing, plots were mowed on January 2nd and 13th, and on February 9th and 16th at a 3” cutting height, with the frequency representing a light grazing treatment.

Table 2. First Hollow Stem (FHS) results for each wheat variety collected at Chickasha. Plots were planted on 9/25/2025, with all sections left unclipped (i.e., not grazed). The FHS threshold is 1.5 cm (5/8″ or approximately the diameter of a dime). Reported values represent the average of ten measurements per variety. Varieties that exceed the threshold are highlighted in red.

Contact your local Extension office and us if you have questions. 

Additional resources available:

Acknowledgments: 

Tyler Lynch, Senior Agriculturalist

Francisco H. Aispuro Arana, Graduate Research Assistant

Israel Molina Cyrineu, Graduate Research Assistant

Yanina Correndo, Graduate Research Assistant

Juan Bautista Bruno, Visiting scholar

Ana Sarah Silveira Barbosa, Visiting scholar

Oklahoma wheat planting – 2025

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Amanda de Oliveira Silva, Small Grains Extension Specialist

Soil moisture conditions are currently favorable for wheat planting across much of Oklahoma. Many of you may be eager to get seed in the ground, but before moving ahead, it is important to consider a few key points.

Planting date

For dual-purpose wheat (grazing + grain), the optimal planting window in most of Oklahoma is mid-September (Figure 1). Planting during this period provides the best balance between fall forage production and maintaining grain yield potential.

  • Early planting may increase fall forage production but also raises the risk of pests and diseases. It’s usually only recommended for wheat intended for graze-out or dual-purpose.
  • Grain-only wheat should generally be planted about 3-4 weeks later (mid-October, Figure 1) in many parts of the state. Our recent work shows there is more flexibility than we thought, and planting a little later can still work well depending on the weather.
Figure 1. Forage and grain yield potential in relation to the day of the year. Every 1,000 kg/ha is equal to approximately 900 lb/acre or 15 bu/acre. Ideal planting dates for dual-purpose wheat in Oklahoma are mid-September (i.e., approximately day 260). Planting for grain-only should occur at least 3-4 weeks after dual-purpose planting (i.e., mid-October or approximately day 285).

Watch for Fall Armyworms

Planting too early increases the chance of fall armyworm infestations. These pests are small and easy to miss, but you might notice “window-pane” feeding on leaves (Figure 2). Check beneath crop residue as well, since they often hide there during the heat of the day (Figure 3).

Figure 2. Symptom of “window paned” leaves shows severe feeding from the fall armyworm. Photo taken on October 2, 2019, at Canadian County by Amanda Silva.
Figure 3. Fall armyworms may be found under crop residue during the day. Photo taken on October 2, 2019 at Canadian County by Amanda Silva.

Volunteer wheat and Virus Risk

Early planting also raises the risk of wheat streak mosaic and Triticum mosaic viruses, spread by the wheat curl mite. Because seed treatments do not control these viruses and few varieties have strong resistance (i.e., Breakthrough), cultural practices are critical:

  • Control volunteer wheat and other grassy hosts as much as possible.
  • Ensure volunteer wheat is completely dead for at least two weeks before planting. This breaks the “green bridge” that mites use to move into new seedlings.
  • Planting a little later can also help lower virus pressure.

We saw significant wheat streak mosaic issues last year, making these steps especially important in 2025.

Other Planting Considerations

Before planting:

  • Soil test to guide fertility needs and reduce input costs.
  • Use high-quality seed to promote good germination and stand establishment.
  • Consider fungicide and insecticide seed treatments to protect against soilborne diseases and early pest pressure such as root rots.

Need More Information?

Your county OSU Extension office is a great resource for information. You can also reach out directly to us:

Pre-harvest sprouting and post-harvest seed dormancy in late harvested wheat

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Amanda de Oliveira Silva, Small Grains Extension Specialist, Oklahoma State University

The Oklahoma wheat harvest was delayed in many areas this year due to frequent rainfall events. I have received several questions about sprouted wheat seeds and potential issues with post-harvest dormancy, especially when using that grain for seed this fall. So, I would like to share a few considerations.

Pre-harvest sprouting

Pre-harvest sprouting refers to wheat grains that begin to germinate while still on the wheat head, before harvest. Once wheat reaches physiological maturity, it can begin to germinate if exposed to ideal moisture and warm temperatures for just a few days. That is what happened in some locations in northcentral OK this season.

The risk of sprouting depends on both genetics and environmental conditions. Wheat varieties differ in their resistance to sprouting (i.e., some are more prone to sprouting than others).

Can I use sprout-damaged wheat for seed?

It depends, especially on the level of sprouting.

  • If wheat kernels appear swollen or with a cracked seed coat, but with no visible root or shoot emerging from the seed, they might still be viable to be used as seed. In this case, run a germination test to assess seed quality before planting.
  • However, if you see visible roots or a developing coleoptile emerging from the seed (see Picture 1), those seeds should not be used. They will likely have poor viability and may fail to emerge.
Picture 1. Pre-harvest sprouted wheat damage, showing grain with split seed coat and radicle starting to become visible. The photo was taken on June 10, 2022 by Glen Calvert, former Extension Ag Educator at Washita County.

Will pre-harvest sprouting damage affect wheat quality?

Yes. As wheat starts to sprout (i.e., begins to germinate), it produces alpha-amylase and other enzymes that break down starch and protein in the grain. Increased enzyme activity can reduce flour and baking quality, affecting dough strength, loaf volume, and crumb structure. The more severe the sprouting, the greater the loss in marketability and end-use quality.

Post-harvest seed dormancy

Since harvest was late this year, will post-harvest dormancy affect planting this fall?

It is possible. Wheat seed is considered dormant when it fails to germinate even under favorable conditions or take so long that emergence is delayed, thus causing poor stands. Dormancy can be worsened when planting in warm soil (above 70F), which is typical during early sowing of graze-out or dual-purpose systems in Oklahoma.

Some level of seed dormancy is beneficial as it helps prevent pre-harvest sprouting as previously discussed. Dormancy is highest right before harvest and gradually decreases over time. But the rate at which it decreases depends on genetics and several other factors, including:

  • Seed coat properties: Inhibitory compounds in the seed coat of hard red winter wheat varieties can extend post-harvest dormancy.
  • Storage conditions: Seed stored at extreme temperatures (hot or cold) tend to lose dormancy faster than those stored at ambient air temperatures. This is why placing seed samples in a refrigerator for a day or two before conducting germination tests is a common practice.
  • Grain-fill environment: Cooler and wetter conditions during grain fill result in stronger dormancy than hot and dry conditions during this period. This means that the same wheat variety may exhibit different germination behavior depending on the environment in which the seed was produced.

For most hard red winter wheat varieties, dormancy naturally dissipates by October. However, early sowing shortens the interval between harvest and planting, which increases the risk of planting dormant seed, leading to delayed emergence and poor stands.

Dormancy can be mistaken by other problems like dead or damaged seeds. Running a germination test can help to identify what is going on.

What to check before planting saved seed:

  1. Germination Test

      Even if the grain didn’t visibly sprout in the head, it may have undergone internal changes (like enzyme activity) that reduce vigor. A standard germination test is the best way to assess viability.

      The Oklahoma Department of Agriculture, Food and Forestry offers this service. Click here for more information.

      2. Fungal infections and seed quality:

      Prolonged wet conditions during grain filling and harvest can lead to seed-borne fungal diseases. These can reduce seed quality and emergence. Consider using a fungicide seed treatment to reduce this risk.  

      3. Test weight and shrunken kernels

      Low test weight and shriveled seeds often indicate poor grain fill. These seeds might have reduced starch reserves, which weakens seedling growth.

      Aim for test weight above 58 lb/bu for seed use.

      Summary

      • Delayed harvest increases the risk of pre-harvest sprouting.
      • Both can impact seed viability and plant emergence this fall.
      • Before using your own grain as seed, be sure to run a germination test and assess overall seed quality.

      Resources: