Stop the March: Starting Your Wheat Season Off Right with Fall Armyworm Management
Ashleigh M. Faris, State Specialist for Cropping Systems Entomology
As Oklahoma summer crops are winding down, we are seeing an increase in fall armyworm reports. Fall armyworms are posing a significant risk of economic damage to our upcoming winter wheat crop. These summer crops and weeds have supported lush vegetation, creating highly attractive habitats for female moths to lay eggs, which can subsequently move into newly planted wheat.
Here is what wheat producers need to know to identify, manage, and prevent fall armyworm infestations this planting season.
Fall Armyworm (FAW) Identification and Life Cycle
Fall armyworms have a distinct, broad, white inverted “Y” present on the front of their head capsule (Fig. 1). Their body varies from light tan to green to dark brown or nearly black in color with three widely separated narrow, yellowish-white stripes down their back (Fig. 2). There are four distinct black dots arranged in a square on the top of the 8th abdominal segment.
Fig. 1 Fall armyworm. Note the white inverted “Y” on the head capsule. Credit: Mitchell Alcala, OSU Agriculture.
Fig. 2. Fall armyworm. Credit: Pat Porter, Texas A&M AgriLife Extension.
The adult moth will lay their eggs that hatch as caterpillars (the damaging stage). Adult moths migrate from Mexico and Texas to Oklahoma usually by late June. Eggs are laid in clusters on host plants and appear pale yellow but darken as they age turning black just before hatching (Fig. 3). Larvae will feed on foliage for 2-3 weeks, increasing with size as they progress through 6 larval instars, then dig into the soil to pupate. A new generation of moths emerge about 2 weeks later. Because there are several overlapping generations in Oklahoma, extending into October and November, protecting wheat stands and monitoring for FAW can be critical for crop establishment. Keep in mind that FAW do not overwinter in Oklahoma; the first killing frost of the season should eradicate the population.
Fig. 3. Fall armyworm eggs laid on grass. The fuzzy appearance is due to scales that are deposited between and over the eggs. Credit: Desiree van Heerden, Syngenta.
Signs of FAW Damage, Scouting, and Economic Threshold
The earliest sign of infestation is “windowpane” damage, where tiny, newly hatched FAW larvae chew off a single layer of leaf tissue, leaving behind transparent patches (Fig. 4). Within a few days, the growing FAW caterpillars can consume entire leaves. Because 90% of crop damage happens during the insect’s final two growth stages, FAW can quickly decimate seedling stands, sometimes forcing producers to completely replant their winter wheat.
Fig. 4. Small FAW larvae will scrape off the top layer of leaf tissue when they feed, leaving behind a “windowpane” appearance. Credit: Lanie Hale, Wheeler Bros.
To scout for FAW, check your fields regularly (e.g., every other day in the evenings), looking closely at the base of newly emerged seedlings. Focus on field borders and edges near grassy or weedy areas where FAW often start. During the day FAW will hide under residue and at the base of the plant, scouting early morning or in the evenings is the best time for spotting FAW in the crop canopy. Look closely and carefully for early instars, as these are very small (Fig. 5).
Fig. 5. Small, early instar FAW can be difficult to see against wheat and residue, especially when scouting in full sun. Red circles highlight the FAW hiding in this image. Credit: Dr. Amanda Silva, OSU Small Grains Extension Specialist.
The economic threshold for FAW in winter wheat is 3 – 4 larvae per linear foot of row alongside visible feeding damage. Alternatively, treat when there are 4 or more larvae (1 inch or longer) per square foot threatening the stand. If 25-30% of plants show window-pane injury, monitor the field daily and treat immediately if the stand is in danger.
Planting Practices: Cultural Control & Insecticide Seed Treatments
Keeping your field and its surrounding borders completely weed-free, in additional to removal of volunteer wheat for at least two weeks before planting is one way to make sure your wheat season starts off on the right foot. This removes early food sources and makes the area less attractive for egg-laying female moths.
Another way to get your season off on the right foot is to consider using an insecticide seed treatment but make sure it is specifically labeled for FAW. This is because not all insecticides are effective against FAW. Seed treatments containing the active ingredient Chlorantraniliprole (Group 28), such as Cedocor CPL and Lumivia, are effective options labeled to control or suppress FAW. These products also provide protection against wireworms, cutworms, and grasshoppers. Insecticide seed treatments can provide protection for four to six weeks.
How do you know if you should invest in a seed treatment? Consider your planting timing and intended use for your wheat. Planting wheat early for use as a dual-purpose crop significantly increases the prevalence of several diseases and damage caused by viruses, fungi, and by insect pests compared to planting wheat later for grain-only. You should also consider the history of the field. If you have seen issues in a particular field, then it may be worth planting treated seed. If you don’t know the history of the field, work with your local agronomist to determine what insects are likely an issue in those fields.
If you are using treated seed, remember that combinations of some fungicidal and insecticidal seed treatments can be toxic to the seed. Read the label carefully before mixing insecticides with fungicides. Also be sure to follow required grazing restrictions and intervals listed on the label. Equipment such as augers and trucks to deliver grain should not be contaminated by treated grain.
Foliar Chemical Control Options
It is critical to treat fields while FAW caterpillars are on the small side meaning less than half an inch long; larger caterpillars do the most damage and can be highly resilient to insecticides. Effective foliar products typically include active ingredients like chlorantraniliprole, lambda-cyhalothrin, spinetoram, or cyfluthrin. Options labeled for FAW control include Coragen eVo, Tombstone, Warrior II, Mustang Maxx, Besiege, and Radiant SC. When selecting an insecticide, it is important to consider if the option is broad spectrum. Broad spectrum insecticides can reduce natural control such as lacewing and syrphid larvae, as well as lady beetles that may be keeping other pests like aphids under threshold. Always read and follow all label instructions to ensure you are applying at the correct rate and adhering to the required pre-harvest and grazing intervals.
This fall, the OSU Cropping Systems Entomology team will be conducting field trials to evaluate the efficacy of insecticide seed treatments and foliar insecticides on FAW in hard red winter wheat. These trials are made possible through support from industry partners and the Oklahoma Wheat Commission. Trial results will be shared at future OSU Field Days and grower meetings.
Cheap Nitrogen is not always the best Nitrogen, Timing matters
Brian Arnall: Precision Nutrient Management Extension Specialist, Oklahoma State University
In 2020, we published a summary of four OSU trial series comparing pre-plant nitrogen (N) to in-season N in grain-only winter wheat. https://osunpk.com/2020/09/10/value-of-in-season-application-for-grain-only-wheat-production/ Since then, three of those trial series have made it through peer review, and additional analyses have added considerably more data to the story. From both historic data from Dr. Raun’s program and new work. All together, these studies now represent more than 90 Oklahoma site-years across a wide range of environments, N rates, and application timings. So, after several more years of research, has the conclusion changed?
Does waiting to apply nitrogen cost wheat yield?
Across these studies, moving N from pre-plant to a properly timed in-season application generally maintained or increased grain yield. How often in-season N increased yield varied among datasets. Souza et al. found that winter wheat could recover from early N stress without sacrificing yield over a surprisingly wide application window. In other studies, in-season N was statistically similar to pre-plant N. The important point is that delaying N did not automatically mean giving up yield.
The Regional N study started by Dr. Raun 2in 2009, adds an important environmental piece to the story. Split N out yielded pre-plant N in approximately 29% of the 52 site-years, specifically those classified as highly responsive to N. These years tend to be wetter environments with greater yield potential. In the remaining 71%, split and pre-plant N produced statistically similar yields. Across all 52 site-years, splitting N never resulted in a significant yield loss compared with pre-plant N.
When a yield advantage with in-season N occurred, it could be meaningful. One study found a single in-season application produced approximately 8% greater yield than a full-rate pre-plant application. Sharry’s Gallagher/Green Hammer study found a single Feekes 4 (spring green up) application averaging approximately 11% greater yield than a single pre-plant application across two varieties and four site-years. The Regional N analysis found an approximately 5.4 bu/ac, or 14%, advantage for split N over pre-plant N in highly N-responsive environments, while there was no difference in the remaining environments. The message isn’t that in-season N always produces more wheat. It doesn’t. Properly timed in-season N generally maintained yield, and about 58% of the time increased it.
Protein Tells an Even More Consistent Story
Protein responded more consistently to N timing than yield. Later N increased grain protein across nearly every dataset. In the Regional N study, split N increased protein by 0.8 percentage points above the pre-plant compared with a 1.1-point increase from all N applied in-season. That advantage occurred across every environmental response category. In the end yield response to delayed N depends heavily on environment. The protein response is considerably more consistent.
If In-Season N Works, Is There a Reason to Split It?
Once the decision is made to move N away from a full pre-plant application, another question follows: should some N still go out pre-plant and the remainder in-season, or can the entire rate wait until the growing season? Two datasets tested that question directly, and neither found a consistent yield advantage to splitting N over a single, well-timed in-season application.
Sharry’s study found that a single green up application out-yielded both two-way and three-way splits by approximately 4.4 to 9.4 bu/ac at the site-years where treatments differed. At no site-year did a split application out-yield the single in-season timing. Abiola (2025) reached essentially the same conclusion. A single in-season application matched or exceeded a 50/50 pre-plant/in-season split across the timings evaluated. There was, however, an important exception. As the single in-season application was pushed into late March and April, having some N already applied reduced the potential downside.
Splitting N appears to be more about risk management than yield management.
Putting some N out early provides insurance against weather, field conditions, equipment problems, or other factors that prevent the planned in-season application from being made on time. If a single in-season application can be made at the proper time, however, these data provide little evidence that splitting N improves yield. So, in the end you reduce the “risk” but double application cost.
Timing Still Matters
None of this should be interpreted as saying N can be applied whenever it is convenient. The window for applying N to grain-only winter wheat is wider than many growers assume, but it isn’t unlimited. As application moves later, the opportunity for unfavorable weather to interfere with N availability becomes increasingly important.
The Regional N study provides a good example. For post top-dress applied N rainfall alone explained 27% of the site-to-site variation in how much the crop responded to N. The environments where split N increased yield over pre-plant N were generally the wetter, higher-yielding environments.
Waiting on N is a management strategy. Waiting too long is not.
Moving N in-season allows the rate decision to be made when considerably more is known about stand, growing conditions, and yield potential. But that flexibility only has value if the application is made while the crop can still effectively use the N. The data shows that the most risk adverse timing falls in the January to mid-March time frame.
What About Fertilizer Price?
Agronomy is only part of the decision. Anhydrous ammonia can provide a substantial cost-per-pound-of-N advantage over fertilizer sources typically used for in-season applications. When that price gap becomes large, the in-season strategy needs to create enough additional value through yield, protein, improved N-rate decisions, or reduced N loss to pay for the more expensive source.
The break-even calculation is straightforward: Additional N cost per acre ÷ wheat price = additional bushels needed to break even. At a 100 lb N/ac rate, every $0.10/lb difference in N price represents $10/ac in fertilizer cost.
For example, if the in-season N source costs $0.30/lb N more, that is a $30/ac disadvantage before the crop is planted. At $4.00 wheat, in-season N needs to produce 7.5 additional bu/ac to cover that difference. At $5.00 wheat, it needs 6 bu/ac, and at $6.00 wheat, it needs 5 bu/ac.
The range becomes fairly large as the difference in N price changes. At a 100 lb N/ac rate and wheat prices between $4 and $6/bu, a $0.20/lb N-price difference requires roughly 3 to 5 additional bu/ac, while a $0.50/lb difference requires roughly 8 to 13 additional bu/ac.
That doesn’t make either strategy automatically more profitable. In environments where yield is the same, the cheaper N source has the economic advantage. Where in-season N increases yield or protein, the economics can move in the other direction. There is also another economic benefit to waiting that is harder to put into a simple table: by waiting, the producer can adjust the N rate to the yield potential that is there rather than the yield potential hoped for before planting.
So fertilizer price adds another question to the N-timing decision: How much is the flexibility of waiting worth this year?
After more than 90 Oklahoma site-years, there is little evidence that grain-only winter wheat inherently benefits from having the entire N requirement available before planting. A properly timed in-season application generally maintains yield and can increase yield under responsive conditions. The opportunity to increase grain protein is even more consistent. Waiting also allows the final N decision to be made when the producer knows considerably more about the crop, weather, and realistic yield potential.
Splitting N does not appear to provide an additional yield benefit over a single, properly timed in-season application. Its primary value is insurance against missing that application window. But fertilizer price matters. When anhydrous or another pre-plant source provides N substantially cheaper than the available in-season source, those savings have real value and should be weighed against the potential benefits of waiting. There isn’t one N-timing strategy that wins every year. The goal isn’t simply to maximize yield or minimize fertilizer cost. It is to choose the N source, rate, and timing combination that provides the best economic return for the conditions in front of you.
These conclusions apply to grain-only winter wheat. Dual-purpose wheat requires sufficient fall growth for forage production and has a different early-season N requirement.
If you have any questions or comments, please feel free to reach out.
Brian Arnall
b.arnall@okstate.edu
Sources
Souza, J.L.B., Antonangelo, J.A., Silva, A.O., Reed, V., and Arnall, B. 2022. Recovery of Grain Yield and Protein with Fertilizer Application Post Nitrogen Stress in Winter Wheat (Triticum aestivum L.). Agronomy 12:2024.
Abiola, S.O., Souza, J.L.B., Sharry, R., Derrick, J.R., Maatougui, M., and Arnall, D.B. 2025. Split nitrogen applications provide no benefit over a single well timed application in rainfed winter wheat. Frontiers in Plant Science 16:1698494.
Ballagh, B., Ballagh, A., Bushong, J., and Arnall, D.B. The Effect of Nitrogen Fertilizer Placement and Timing on Winter Wheat Grain Yield and Protein Concentration.
Sharry, R. 2025. Response to nitrogen timing of varying winter wheat genotypes Dissertation, https://hdl.handle.net/20.500.14446/344867
Regional N study. 52 Oklahoma site-years, 2009–2023, Okstate Soil Fertility data unpublished.
Be on the Lookout: The Pasture Mealybug (Heliococcus summervillei), An Emerging Threat to Pasture and Hay
Ashleigh M. Faris1, Kelly Seuhs1, and Kenny Naylor2
1Department of Entomology and Plant Pathology, Oklahoma State University
2Consumer Protection Services, Oklahoma Department of Agriculture, Food, and Forestry (ODAFF)
The pasture mealybug is not currently detected in Oklahoma. However, this invasive pest is spreading rapidly across the Gulf Coast and neighboring states. Oklahoma producers should remain vigilant, proactively scout pastures, and understand how to prevent its introduction.
Background & Threat
Originally described in Australia, the pasture mealybug, Heliococcus summervillei, was first detected in the United States in Texas (2025). The pest has since been confirmed in 70 Texas counties, as well as in parts of Louisiana and Florida (Figure 1). The pasture mealybug exclusively feeds on grasses—including Bermudagrass, Bahiagrass, bluestems, and other tropical/subtropical forage grasses.
Figure 1. Current documented distribution of the pasture mealybug in the United States. Credit: EDDMapS, https://www.eddmaps.org/distribution/uscounty.cfm?sub=110977.
The pest injects toxic saliva into the plant while feeding on sap. This weakens the grass, makes it susceptible to secondary fungal infections, and leads to a devastating condition known as “pasture dieback.” Millions of acres of highly productive grazing land have been lost in Australia, and U.S. producers are currently seeing massive yield reductions in heavily infested areas.
Pest Identification & Biology
Pasture mealybugs are tiny, highly mobile, and can easily go unnoticed until significant damage occurs. They prefer the lower parts of the plant canopy. Look on the undersides of the lower leaves, deep in the thatch layer, at the soil surface, on the roots, or even clustered under dried cow patties.
- Size and Appearance: Adult females are small (2 – 5 mm long), oval-shaped, and covered in a white, powdery, or “mealy” wax. They are covered in fine hairs extending from all sides of their bodies (Figure 2). Adult males are rarely seen due to their short lifespan. Males are winged, have a long wax tail and do not feed.
- Color Changes: Older, mated females turn a distinct pink color.
- Nymphs (Crawlers): The youngest nymphs are the most active feeders but are nearly invisible to the naked eye (less than 1 mm).
Figure 2. Close up of adult female pasture mealybug (left) and pasture mealybug on hand (right). Credit: Isaac Esquivel, University of Florida Extension.
Damage Symptoms
Immature pasture mealybugs secrete honeydew as they feed. This honeydew can promote sooty mold fungi which can inhibit photosynthesis. Because mealybugs inject a toxin, grass injury can appear within a week of infestation. Symptoms are often mistaken for drought stress, nutrient deficiency, or disease.
- Yellowing: The earliest symptom is a general yellowing of the older leaves (Figure 3).
- Reddening/Purpling: As the dieback progresses, leaves develop distinct red or purple streaks starting from the leaf tip and moving downward (Figure 3).
- Desiccation and Death: The plant eventually dies due to premature senescence which allows opportunistic pathogen infections to kill the grass, leaving expanding patches of dead, brown grass in the pasture (Figures 4 and 5).
Figure 3. Yellowing (left) and reddening (right) of grass affected by pasture mealybug feeding. Credit: Danielle Sekula and Stephen Biles, Texas A&M AgriLife Extension Service.
Figure 4. Pasture dieback caused by pasture mealybug. Credit: Isaac Esquivel, University of Florida Extension.
Figure 5. Severe pasture dieback caused by pasture mealybug. Credit: Stephen Biles, Texas A&M AgriLife Extension Service.
Scouting and Monitoring Practices
Since the pasture mealybug is not yet established in Oklahoma, early detection is our best defense.
- Check the Edges: Do not look for mealybugs in the completely dead patches of grass. Instead, scout the green, actively growing edges surrounding areas of yellowing, reddening, and poorly grown grass.
- Part the Canopy: Get down to the soil level. Pull the grass stems back at the soil surface and inspect the undersides of lower leaves, thatch, and root crown (Figure 6).
- Check Hay: In fields recently cut for hay (14 – 30 days post-cutting), check the remaining stubble near the ground.
Figure 6. Adult female pasture mealybug in Bahiagrass. Credit: Isaac Esquivel, University of Florida Extension.
Sanitation and Spread Prevention
Pasture mealybugs move easily. Their tiny nymphs can be blown by the wind, hitchhike on clothing, or be transported on farm equipment.
- Equipment Hygiene: Never drive trucks, ATVs, or tractors into an infested field unless necessary. If you do, thoroughly pressure wash the equipment, tires, and undercarriages and remove any grass clippings before moving to an uninfested pasture. In cases where water is not available, sweeping or blowing equipment is advised. Thoroughly inspect any equipment for pasture mealybugs even after cleaning before moving to another location.
- Clothing Hygiene: Clean boots/shoes and pants when moving between fields (Figure 7). If working in a field that has suspected pasture mealybug damage wear protective coverings that can be disposed of after use and before moving into another pasture.
- Hay and Sprigs: The pest can be transported in freshly cut hay or infested grass sprigs. Do not source sprigs from known infested regions.
- Work Order: Always manage and scout your clean, uninfested pastures first before moving to pastures you suspect might have an issue.
Figure 7. White specks on boot are wax from pasture mealybug after walking through an infested pasture. White specks on blades of grass are pasture mealybug. Credit: Isaac Esquivel, University of Florida Extension.
Cultural Management Options
If the pest is detected, cultural practices can help suppress population numbers. The pasture mealybug thrives in tall, thick, dense grass canopies, which protect it from the elements and predators.
- Reduce Biomass: Shredding, cutting for hay, or utilizing intensive, heavy grazing reduces the dense canopy the insect prefers.
- Baling: If cutting an infested field, baling and removing the dry material removes their food source. Data from Texas shows that 48 hours after cutting, only about 5% of mealybugs remain in the drying hay, as they leave searching for live plant sap.
- Re-establishment: If a pasture is entirely lost to dieback, the dead biomass should be completely removed before replanting a less susceptible/less preferred grass species to reduce mealybug survival rates. More research is needed to identify these grasses.
Chemical Control Guidelines
Controlling the pasture mealybug chemically is difficult. The pasture mealybug’s waxy coatings, overlapping life cycles, and preference for hiding deep in the soil thatch mean getting good chemical coverage is challenging.
- Avoid Broad-Spectrum Insecticides: General pasture insecticides like pyrethroids (Group 3A), organophosphates (Group 1B), and carbamates (Group 1A) have shown very poor efficacy against this pest. Furthermore, they kill beneficial predators and parasitoids that may naturally help keep mealybug populations in check.
- Application Timing is Critical: Never spray a tall, dense pasture. You must first cut, shred, or graze the grass to reduce the canopy. Allow the grass to regrow to 6 – 8 inches so there is fresh, green tissue to absorb the chemical before making an application. The use of adjuvants, like methylated seed oils, is highly recommended to improve leaf absorption.
- Effective Chemistries: While not all are permanently labeled for pastures in every state, research from Texas and Florida indicates that certain systemic products are effective. Currently the only product labeled for pasture mealybug in Oklahoma is Sefina® Inscalis® (ai: afidopyropen, 4.89%) at 8-10 fluid ounces per acre. However, this product provides at best suppression and is not recommended for high infestations or sites where grass injury is pronounced. Chemical control options are still being evaluated, and more information will be shared as it becomes available.
Important Regulatory Note for Oklahoma: Because this pest is not yet established in Oklahoma, Section 18 Emergency Exemptions are not currently available. These exemptions provide temporary authority to use certain pesticides that are not otherwise labeled for this specific pest. Always read and follow all label directions.
What to Do If You Suspect an Infestation
Oklahomans who observe unexplained pasture dieback or find small, white, waxy insects like the photos above or as described, should collect a sample immediately. Package grass clippings in a loose, dry paper towel or crumpled newspaper set inside a Ziploc bag that is sealed and placed in a small box. Do not add water to the sample or Ziploc bag. Submit the prepared package to the local county Extension office (https://extension.okstate.edu/county) for shipment to the Oklahoma State University Plant Disease and Insect Diagnostic Laboratory for confirmation by state entomologists. The Oklahoma Department of Agriculture, Food and Forestry may follow up with you for additional information.
Oklahoma Nitrogen Prices Continue to Move Lower 8.10.26
Nitrogen prices continued to decline in Oklahoma during the past two weeks, led by anhydrous ammonia. The statewide NH₃ reference fell $72 per ton to $875, while urea and both UAN concentrations also declined. The four-week decrease now exceeds 10% for NH₃ and approaches 7% for UAN 28. Phosphate and potash prices, meanwhile, have changed very little.
The Oklahoma average, minimum and maximum prices shown in the accompanying graphic come from the USDA AMS Oklahoma Production Cost Report. USDA collects FOB asking prices from Oklahoma distributors but does not identify the contributing dealers or disclose the number of observations. Public cash quotes from named dealers, including Two Rivers Cooperative, are tracked separately and are not blended into the USDA regional statistics.
The immediate Oklahoma explanation for softer nitrogen prices is relatively straightforward: hot, dry conditions have slowed fertilizer movement. USDA reported reduced demand across the fertilizer market, with triple-digit temperatures accelerating corn dry-down and allowing harvest to begin in parts of the state. With limited field activity and the primary summer application season behind us, dealers have less nearby demand supporting nitrogen values.
International nitrogen conditions are also becoming less restrictive. Fertilizer-market analyst Josh Linville reported that urea values continue to face pressure from weaker demand and a second round of approved Chinese exports. Additional Chinese availability matters because it gives international buyers another major supply origin and reduces competition for other export tons.
Nutrien’s second-quarter results reinforce the mixed nature of the nitrogen market. Global nitrogen benchmarks remained elevated, but second-quarter nitrogen sales volumes were lower. The market will now be watching whether increased export availability is sufficient to offset upcoming fall demand and additional international purchasing.
Phosphate remains a different story. Oklahoma DAP was unchanged during the latest reporting period, while MAP declined only $1.25 per ton. Stable local prices should not be interpreted as evidence that upstream supply risks have disappeared. Linville reported that Moroccan TSP and MAP are moving toward North America, which could improve regional availability. However, phosphate production continues to face elevated sulfur and ammonia costs and limited export availability from some traditional suppliers. These factors may support replacement costs even while weak seasonal demand keeps Oklahoma prices from moving higher.
Potash remains the most stable major nutrient. Oklahoma’s reported average increased only 50 cents per ton. Nutrien reported higher global potash benchmarks and record first-half sales volumes, but it also reported record production. Strong supply performance helps explain why firm global demand has not produced a significant Oklahoma price movement.
For Oklahoma producers, the most important development is the continued separation between nitrogen and phosphate markets. Lower nitrogen quotes may create purchasing opportunities, but the wide reported ranges make direct comparisons essential. Phosphate prices are locally steady but remain exposed to sulfur, ammonia and import-supply risks. Confirm the cash price, nutrient analysis, pickup or delivery basis, quote expiration and application charges before comparing dealer offers.
Fertilizer markets, local prices and product availability can change quickly. Confirm all prices and terms with local dealers before making purchasing decisions.
**The Oklahoma average, minimum and maximum prices shown in the accompanying graphic come from the USDA AMS Oklahoma Production Cost Report. USDA collects FOB asking prices from Oklahoma distributors but does not identify the contributing dealers or disclose the number of observations. Public cash quotes from named dealers, including Two Rivers Cooperative, are tracked separately and are not blended into the USDA regional statistics.
Market Sources
- USDA Agricultural Marketing Service. Oklahoma Production Cost Report. August 7, 2026. https://www.ams.usda.gov/mnreports/ams_3621.pdf
- Linville, Josh. Fertilizer-market commentary. August 7, 2026. https://x.com/JLinvilleFert
- Nutrien. Nutrien Reports Second Quarter 2026 Results. August 5, 2026. https://www.nutrien.com/news/press-releases/nutrien-reports-second-quarter-2026-results-1753
- Reuters. Nutrien Misses Profit Estimates as Lower Volumes Blunt Higher Fertilizer Prices. August 6, 2026. https://www.reuters.com/world/americas/nutrien-misses-profit-estimates-lower-volumes-blunt-higher-fertilizer-prices-2026-08-06/
- Two Rivers Cooperative. Fertilizer Index. Accessed August 10, 2026. https://www.tworiversks.coop/pages/custom.php?id=19995
This report is produced via Chat GPT Plus Work, with review by Brian Arnall.
OSUNPK Fertilizer Market Outlook — July 27, 2026
Produced by Chat GPT Work, reviewed by Brian Arnall, OSU Precision Nutrient Management.
Oklahoma fertilizer markets moved in two different directions during the latest reporting period. Nitrogen prices generally declined, while phosphate and potash remained nearly steady. That local stability does not mean the broader market is free of risk. International production costs, sulfur availability, trade flows and large import programs continue to influence the prices Oklahoma producers may encounter later in the season.
The USDA’s July 24 Oklahoma report placed urea at an average of $672.29 per ton, down $14.42 from the previous report. UAN 28 declined $16 to $472.60, UAN 32 fell $5 to $548.86, and anhydrous ammonia declined $29 to $947. One reported urea quote fell by approximately $300 per ton, while an NH₃ quote moved below $900 and a UAN 28 quote dropped below $400. Those individual movements contributed to unusually wide ranges and should not be treated as representative statewide prices without verification.
The USDA attributed part of the softer market to reduced fertilizer demand during triple-digit heat. Seasonal demand also appears less urgent following major spring and early-summer applications. However, the spread between low and high quotes remains substantial: $365 per ton for urea, $232 for UAN 28 and $225 for NH₃. Those differences make product basis, location and service charges particularly important when comparing offers. (USDA Oklahoma Production Cost Report)
International nitrogen conditions remain uncertain. Fertilizer-market analyst Josh Linville recently identified the resumption of vessel traffic through the Strait of Hormuz and the possibility of renewed Chinese urea exports as potentially bearish influences. Either development could improve global availability. However, fertilizer remains expensive relative to grain prices, and freight, energy or geopolitical disruptions could quickly change the cost calculation. (Josh Linville market commentary)
Oklahoma phosphate prices showed little immediate movement. DAP averaged $952.78, an increase of $2.22, while MAP held at $942.88. The local numbers appear quiet, but upstream phosphate conditions deserve attention. Linville has noted renewed strength in international phosphate values as limited sulfur availability and high production costs constrain output.
Sulfur matters because it is used to produce sulfuric acid, a critical input in manufacturing phosphoric acid and finished phosphate fertilizers such as DAP and MAP. Ammonia is another important production input. Consequently, higher sulfur or ammonia costs can support phosphate prices even when Oklahoma retail quotations have not yet responded. This is an upstream warning signal rather than a prediction that local prices must rise. (Josh Linville on phosphate and sulfur, World Bank fertilizer-market analysis)
Potash remained the quietest major nutrient in Oklahoma. The reported average increased only 75 cents to $491.55, with a range of $460 to $550. Global potash supply is geographically broader than the supply chain for several nitrogen and phosphate inputs. Expanded or recovering shipments from major producing regions may help moderate market pressure, although trade restrictions, transportation constraints and regional demand can still affect delivered costs.
International buying also remains important. India reported importing more than 3.2 million metric tons of urea and DAP during its first fiscal quarter and is pursuing longer-term overseas supply agreements. Large import programs can affect competition for available urea and phosphate cargoes, especially when export availability is already uncertain. (Times of India fertilizer-import report)
For Oklahoma producers, the current report offers a somewhat more favorable nitrogen signal, but not a uniform one. Wide quote ranges mean that comparison shopping may be as important as the regional average. Phosphate prices are locally stable, while sulfur availability and production costs remain meaningful external risks. Potash is comparatively steady.
Before acting on any quotation, confirm the nutrient analysis, cash-price basis, pickup or delivery terms, quote expiration and whether application or blending charges have been separated. UAN quotations should always be identified as either 28% or 32% before comparison.
Market Sources
Scout, Identify, Control: Winning the Battle Against Sorghum Headworms
Ashleigh M. Faris, Cropping Systems Entomologist
This week the OSU Cropping Systems Entomology crew detected treatable numbers of sorghum headworms at several North Central Oklahoma sorghum fields at milk to soft dough stages (Figure 1). Sorghum headworms are a complex of different caterpillar pests that can inflict severe economic damage on grain sorghum during its reproductive stages. The two primary species comprising the headworm complex in our region are the fall armyworm, Spodoptera frugiperda, and the corn earworm, Helicoverpa zea. A third species in this complex is the sorghum webworm, Nola sorghiella. Because these pests feed hidden in the developing sorghum head, timely scouting is important for protecting yields.
Pest Identification
Fall armyworm, corn earworm, and sorghum webworm are all moths as adults. The immature forms, caterpillars which are also referred to as “worms”, are the economically damaging stages. These caterpillars will progress through multiple instars, increasing in size and appetite as they grow. Oklahoma has multiple, overlapping generations of these pests. See Table 1 for identifying characteristics of sorghum headworms.
Table 1. Sorghum headworm identification. Image credits: Fall armyworm, OSU Extension. Corn earworm, Ashleigh M. Faris, OSU Extension. Sorghum webworm, Cliff Beaton, Mississippi Entomological Museum.
| Pest | Image | Body Characteristics |
| Fall Armyworm |  | Dark head capsule with a distinct, broad, white inverted “Y” shape. Dorsal lines running lengthwise down the body. Range in color from light green, brown, or tan. |
| Corn Earworm |  | Light-colored head capsule. Alternating light and dark stripes along the body. Body covered with small bristles visible with a hand lens. Vary in color from green and yellow to brown or pink. |
| Sorghum Webworm |  | Four distinct reddish-brown stripes down the back Many spines and clear white hairs on their body, grouped in clusters. |
Sorghum Vulnerability and Damage
Sorghum is most vulnerable to headworm infestations from panicle emergence (bloom) through the hard dough stage. Fall armyworms and corn earworm can also be considered whorl worms, caterpillars that feed during the vegetative sorghum stages. Whorl-stage feeding causes “windowpaning” (Figure 1) and “shot holes” (Figure 2) on the leaves, but this damage rarely reduces yields enough to justify chemical control. Open-headed sorghum varieties are more susceptible to headworm infestations than tight-headed varieties. Tight-headed varieties make chemical control penetration much more challenging but using high gallon per acre (GPA) when spraying can help.
Figure 1. “Windowpaning” caused by early instar whorl worms feeding on a sorghum leaf. Image credit: Ashleigh M. Faris, OSU Extension.
Figure 2. “Shot holes” caused by later instar whorl worms on a sorghum leaf. Image credit: Ashleigh M. Faris, OSU Extension.
Headworms directly feed on flowering parts and the developing starches within the grain (Figures 3 and 4). They feed in an irregular pattern on the sorghum head, leaving the starchy portion of the kernel exposed (Figure 5). A single larva can consume approximately 0.01 pounds of grain (up to 12 kernels per day) during its lifespan. Infestations of 1 to 2 larvae per head can result in a 5% to 10% overall yield loss.
Figure 3. Early instar corn earworm feeding on developing sorghum kernels. Image credit: Ashleigh M. Faris, OSU Extension.
Figure 4. Late instar corn earworm feeding on developing sorghum kernels. Image credit: Ashleigh M. Faris, OSU Extension.
Figure 5. Sorghum webworm feeding damage. Note the empty glumes and irregular feeding pattern. Image credit: Ron Schnell, Texas A&M University.
Scouting Procedures
Active monitoring gives producers the best chance at making timely insecticide applications. Scouting should begin at full panicle emergence and continue every 3 to 5 days until the hard dough stage. OSU Extension Specialists have developed a sequential sampling Sorghum Headworm Quick Count Sampling Plan to aid growers in management decision making. This support tool can be found at the OSU EPP-7087 Fact Sheet Sampling for Sorghum Headworms in Oklahoma Using the Headworm Decision Support System.
Alternatively, one can also scout for headworms using the following steps:
- Walk at least 15 to 20 feet into the sorghum field before taking your first sample.
- Grasp the stalk just below the emerged head and bend it into a white 2.5 – 5-gallon bucket.
- Vigorously beat the head against the side of the bucket to dislodge the larvae.
- Ignore any caterpillars smaller than 1/4 inch, as they feed very little and experience extremely high natural mortality.
- Count and categorize the remaining worms as either medium (1/4 – 1/2 inch) or large (greater than 1/2 inch).
- Walk 30 paces down the row, sample another head, and repeat this process across multiple rows to ensure field-wide representation.
Economic Threshold for Sorghum Headworms
Management decisions should be driven by the size of the larvae and the growth stage of the crop. When sorghum is in the reproductive/panicle stage, use a treatment threshold of 1 to 2 larvae per head for corn earworms or fall armyworms, or 0.5 headworms per head using sequential sampling. The threshold for smaller, less damaging pests like the sorghum webworm is higher, at 3 to 4 larvae per head.
Insecticide Management Options
If economic thresholds are met, selecting the appropriate chemistry is vital for control and the preservation of natural enemies. Spraying broad-spectrum insecticides like pyrethroids or carbamates can kill beneficial insects that are predators of sorghum aphids and other pests (Table 2). Removing these natural enemies can cause sorghum aphid populations to flare and reach/exceed economic thresholds. Always read the label to ensure the product is registered for use on sorghum and the target pest, and to be aware of restricted entry intervals (REI) and pre-harvest intervals (PHI).
Table 2. List of select available products labelled for managing headworms in grain sorghum in Oklahoma as of the date of this publication. Note that inclusion of insecticide in the table below is not an endorsement or guarantee by OSU Extension. Refer to and follow insecticide labels.
| Insecticide Active Ingredient | Trade Name | Notes |
| Spinosad | Blackhawk | Soft on natural enemies. |
| Chlorantraniliprole | Vantacor (formerly Prevathon) | Excellent option for larger worms and populations resistant to pyrethroids; provides effective control with lower toxicity to natural enemies. |
| Zeta-cypermethrin, lambda-cyhalothrin | Mustang MAXX EC, Warrior II with Zeon | Broad-spectrum activity may impact beneficial/natural enemy insect populations, potentially flaring sorghum aphids. |
How Much Nitrogen Does Double Crop Corn Need in Oklahoma?
Kelby Linn, MS Precision Nutrient Management
Emily Staton, MS Precision Nutrient Management
Josh Lofton, Cropping Systems Management
Brian Arnall, Precision Nutrient Management
Double crop (DC) corn is gaining attention in Oklahoma as producers look for opportunities to increase productivity following wheat harvest. While DC soybeans and sorghum remain common options, corn can serve as an alternative when planting windows are missed or when producers want to diversify their rotation. In Oklahoma systems, it is suggested DC corn is followed by a full season soybean crop the next year. This allows producers to maintain an intensive cropping system while maximizing land use. However, managing fertility in DC corn can be challenging because the crop is grown under a different environment than full season corn. One of the questions producers ask is how much nitrogen (N) is needed to maximize returns. Nitrogen is typically the largest fertilizer expense in corn production, but applying more N does not always result in higher yields. Recent Oklahoma research suggests DC corn may require less N than many would expect.
Understanding the System
To evaluate N requirements under Oklahoma DC conditions, field trials were conducted across 11 site years during the 2024 and 2025 growing seasons (Table 1). Corn was planted directly into wheat residue following harvest, creating a true DC production system. Nitrogen was applied as urea (46-0-0) at 13 rates ranging from 0 to 180 lbs N/acre in 15 lb N increments. The following data was collected: biomass production, grain yield, and grain quality responses across environments. The goal was to identify how much N is needed to maximize yield and profitability in Oklahoma DC corn.
Table 1. Field study locations for the 2024 and 2025 double crop corn trials in Oklahoma. Each location is listed with respective planting dates, corn varieties, planting populations and harvest date.
| Location | Planting | Variety | Population | Harvest |
| Perkins | 6/28/2024 | DK119-30 | 20k | 11/9/2024 |
| 7/11/2025 | DKC117-27RIB | 20k | 11/14/2025 | |
| Stillwater | 6/30/2024 | DK119-30 | 20k | 11/11/2024 |
| 7/12/2025 | DKC117-27RIB | 20k | 11/13/2025 | |
| Perry | 6/28/2024 | DK119-30 | 20k | 11/16/2024 |
| 7/7/2025 | DKC117-27RIB | 20k | 11/12/2025 | |
| Perry (Irrigated) | 7/7/2025 | DKC117-27RIB | 28K | 11/12/2025 |
| Lahoma | 7/9/2025 | DKC117-27RIB | 20k | 11/18/2025 |
| Fort Cobb (Irrigated) | 7/2/2025 | DKC117-27RIB | 28K | 11/15/2025 |
Yield Response: Nitrogen Helped, But Only to a Point
Across all harvested site years, N applications significantly influenced grain yield when environment was not the limiting factor. Average yields ranged from 40 to 94 bu/ac, demonstrating how variable DC corn performance can be from year to year and field to field (Staton, 2026) (Figure 1). While some locations responded positively to N fertilizer, others showed little response even when rates reached 180 lbs N/ac. The consistent finding was yield responses often plateaued around 60 lbs N/ac. Once this point was reached, additional fertilizer rarely produced enough additional grain to justify the added cost. Across two Oklahoma studies representing 11 site-years, unfertilized double-crop corn averaged approximately 52 bu/ac. That finding highlights just how much nitrogen can be supplied by the soil through residual nitrate and mineralization before fertilizer is applied. These results suggesting existing soil N and nutrient mineralization contributed significantly to crop demand (Staton, 2026).
Figure 1. Increase in yield of the highest yielding treatment as compared to the non-fertilized check yields of each location. Adapted from Staton (2026)
The Real Story: Return on Investment
While producers naturally focus on maximizing yield, these fertilizer decisions should be based on profitability. Average economic return peaked near 60 lb N/ac. Beyond that rate, additional fertilizer consistently reduced profit (Figure 2). Although individual economic returns varied among environments, the agronomic data suggest producers should approach DC corn fertility programs with realistic yield expectations. Unlike high yielding full season corn, DC systems often encounter environmental limitations that reduce the return on additional fertilizer investment.
Figure 2. Average profit response to nitrogen rate in US dollars (USD)/ac. Adapted from Staton (2026).
What This Means for Oklahoma Producers
The results from this study closely align with previous Oklahoma research evaluating N response in DC corn. Wyma (2022) reported approximately one additional bushel of grain for every 1.8 lbs N applied above the unfertilized control, similar to Staton (2026) who observed one additional bushel for every 1.7 lbs N in responsive environments. Together these studies suggest Oklahoma DC corn requires approximately 1.75 lbs N for every additional bushel of expected yield above 50 bu ac-1.
The goal of nitrogen management is not to apply the most fertilizer, it is to apply the right amount. Two independent Oklahoma studies now indicate that double-crop corn often requires substantially less N than full-season corn. Matching N rates to realistic yield potential can improve profitability while reducing unnecessary fertilizer costs.
Take Home
- Double crop corn is a economically viable option in Oklahoma.
- Use lower total N rates than full-season corn.
- Across two independent studies’, the unfertilized corn averaged about 50 bushels per acre.
- 1.75 lb N per expected additional bushel above the unfertilized expectation.
- Base final N rates on realistic yield potential and expected moisture.
- Consider residual soil nitrate following wheat before increasing fertilizer rates.
- Avoid applying N beyond expected crop demand.
References
Alcoz, Mercedes M., Frank M. Hons, and Vincent A. Haby. 1993. “Nitrogen Fertilization Timing Effect on Wheat Production, Nitrogen Uptake Efficiency, and Residual Soil Nitrogen.” Agronomy Journal 85(6):1198–1203. doi:10.2134/agronj1993.00021962008500060020x.
Chang, Jen-Hu. 1981. “Corn Yield in Relation to Photoperiod, Night Temperature, and Solar Radiation.” Agricultural Meteorology 24:253–62. doi:10.1016/0002-1571(81)90049-2.
Kravchenko, Anatoliy G., and Kurt D. Thelen. 2007. “Effect of Winter Wheat Crop Residue on No-Till Corn Growth and Development.” Agronomy Journal 99(2):549–55. doi:10.2134/agronj2006.0192.
Liu, Zheng, Jia Gao, Fei Gao, Shuting Dong, Peng Liu, Bin Zhao, and Jiwang Zhang. 2018. “Integrated Agronomic Practices Management Improve Yield and Nitrogen Balance in Double Cropping of Winter Wheat-Summer Maize.” Field Crops Research 221:196–206. doi:10.1016/j.fcr.2018.03.001.
Staton, Emily. 2026. “Nitrogen Management in Double Crop Corn” M.S., Oklahoma State University, United States — Oklahoma.
Wyma, Rhiannon Nichole. 2022. “Corn Grain Yield Response to Nitrogen Rate and Plant Population in Full and Double-Crop Systems.” M.S., Oklahoma State University, United States — Oklahoma.
Don’t Let the Heavy Rains Fool You – Scouting for Sorghum Aphids and Chinch Bugs in Sorghum
Ashleigh Faris, Cropping Systems Entomologist and IPM Coordinator
Depending on where you are in Oklahoma, you may have had anywhere between just under 0.5” or over 7.5” of rain in the last 7 days. If you were on the higher end, you may think that the rainfall has helped to prevent or wash off any insect pests building up in your summer crops. Unfortunately, this isn’t case; this morning sorghum aphids and chinch bugs were detected in research plots in northern Payne County. With rain out of the forecast and typical summer temperatures kicking in these insects, and other pests, can start to take off. Both pests have the potential to inflict severe economic damage if left unchecked, particularly during vulnerable crop stages or near recently harvested wheat. Scout now, and if needed, get together a plan to help you keep these economically damaging pests in check.
Sorghum Aphid, Melanaphis sorghi
Formerly known as the sugarcane aphid, the sorghum aphid can infest sorghum at any growth stage but causes the most severe damage from the boot to soft dough stages. The aphids form dense colonies on the undersides of leaves and produce heavy amounts of honeydew that can negatively affect plant growth and severely impede harvest.
Identification: Sorghum aphids are small aphids with light tan to pale yellow bodies, black feet, black antennae, and black cornicles (the two “tailpipes” on the back of the abdomen) (Figure 1).They almost exclusively reside on the underside of the leaves, often nestled against the midrib (Figure 2).
Figure 1. Sorghum aphids are light tan to yellow in color, have black legs, black antennae, and black cornicles (two tailpipe-like appendages at the tip of their abdomen. Photo credit: Oklahoma State University IPM.
Figure 2. Sorghum aphid nymphs and adults along the midrib of a sorghum leaf. Photo credit: Ashleigh M. Faris, Oklahoma State University Extension.
How to Scout Sorghum Aphids: Begin scouting once a week and increase to twice a week once the aphid is detected. There are two primary ways to scout:
- Option A: The Glance-N-Go App (Recommended) Download the SCA Glance-N-Go App (available on Apple and Google Play). Enter your control cost (
/bushel). Sample two leaves per plant until the app tells you whether to treat or not. It tracks the threshold automatically based on your specific economic variables.
- Option B: The Pen-and-Paper Method
- Walk 90 feet into the field. Inspect the top and bottom leaves of 3 consecutive plants, walk 5 rows over, and sample 3 more plants. (This is 1 “stop” = 6 plants).
- Walk 30 feet in an inverted “U” shape to your next stop and repeat.
- Complete 9 total stops (54 plants total).
- Record the number of plants that have 50 or more aphids.
Sorghum Aphid Economic Threshold: If using the manual method (Option B), the threshold to treat is when 25% of the plants are infested with 50 to 125 aphids per leaf. Do not spray before the threshold is met, as premature spraying can disrupt the natural enemies (lady beetles, lacewings, parasitic wasps) that naturally keep sorghum aphid populations in check.
Sorghum Aphid Management: Sivanto 200 SL and Transform WD are recommended insecticides as both are soft on beneficials and provide good residual. Follow label rates and directions. Coverage is critical so apply with high water volume (5+ gallons/acre by air; 10+ gallons/acre by ground). Avoid pyrethroids. Using pyrethroids to control secondary pests (like headworms once at grain fill) even when aphid numbers are low will wipe out beneficial insects, frequently causing sorghum aphid populations to explode.
Chinch Bug, Blissus leucopterus
Newly seeded sorghum (think double-crop and late planted sorghum for this time of the year) is especially at risk for chinch bug damage. Chinch bugs frequently migrate into sorghum fields looking for a new food source once adjacent wheat fields mature and are harvested.
Identification: Adult chinch bugs are about 1/8 inch long, black body with white wings folded over their back. The wings have distinctive black, triangular markings (Figure 3). Chinch bug nymphs (immatures) are bright red/orange right after hatching (Figure 4). They gradually darken to brown/black as they mature. They do not have wings but do have a light-colored band across their abdomens.
Figure 3. Chinch bug nymphs photographed with a microscope. Nymphs are wingless, early nymphal stages are orange to red in color with a white band, later nymphal stages are darker in color. Photo credit: Jacie Guerrero and Nikolai Thielepape, Department of Entomology and Plant Pathology, Oklahoma State University Extension.
Figure 4. Chinch bug adults have black bodies and white wings that give a triangular shape to the chinch bug’s back when folded over. Photo credit: Ashleigh M. Faris, Oklahoma State University Extension.
How to Scout Chinch Bugs: Focus on border rows adjacent to harvested wheat or thin stands. Double-cropped sorghum planted directly into wheat stubble is at the highest risk, but we have detected chinch bugs in full-season planted sorghum throughout North Central Oklahoma. Chinch bugs pierce the plant and suck the sap, injecting toxins as they feed. Look for stunting, wilting, reddish discoloration on the stalk, or poor root development (Figure 5).Check the leaf blades, but importantly, look under the leaf collars/sheaths and down at the base of the plant near the soil line where the chinch bugs hide (Figure 6).
Figure 5. Chinch bug damage and chinch bug nymph on sorghum stalk. Photo credit: Ashleigh M. Faris, Oklahoma State University Extension.
Figure 6. Chinch bug nymphs and damage to sorghum stalks found by peeling back lower sheaths of damaged sorghum stalks.Photo credit: Ashleigh M. Faris, Oklahoma State University Extension.
Chinch Bug Economic Threshold: For sorghum seedlings (less than 6 inches), treat if 2 or more chinch bugs are found on 20% of the plants.Larger plants (over 1 foot), treat if you find 10 or more chinch bugs per plant.
Chinch Bug Management: The best defense is an insecticide seed treatment (e.g., Gaucho, Poncho, or Cruiser), which provides about two to three weeks of early control. Avoid planting sorghum directly adjacent to poor wheat stands if possible.If migrating populations breach the threshold, foliar pyrethroids are the primary option (e.g., lambda-cyhalothrin or zeta-cypermethrin). Because chinch bugs hide behind leaf sheaths and at the soil level, high water volume is essential to achieve proper penetration and coverage on small plants. Spot treatments on border rows are often enough if the migration is caught early and chinch bugs have not spread into the field.
Dr. Ashleigh Faris’s Cropping Systems Entomology IPM team is currently conducting chinch bug insecticide efficacy trials. Stay tuned for the results!
For detailed insecticide rates and grazing/post-harvest intervals, always consult the product’s label guidelines and read the label carefully before application.
Bigger Isn’t Always Better: The Relationship Between Plant Size, Yield Potential, and Yield Stability in Summer Crops
Josh Lofton, Cropping Systems Specialist
In the last several years, warmer springs and higher/widespread rainfall have resulted in summer crops reaching with a high amount of vegetative growth. This season has been quite different for the most part, cooler temperatures and more sporadic rainfall has resulted in much smaller plants. So that begs the question, are larger or smaller plants better for yield in Oklahoma. While many that have spent time in Oklahoma will probably have a preference, there is no direct answer to this question.
Larger plants generally have more leaves, more stems, more branches, and more overall biomass. They often appear healthier and more productive throughout the growing season.
In higher rainfall and lower stress environments, this assumption is true. Greater vegetative growth can support higher yield potential because larger plants capture more sunlight, accumulate more photosynthates, and develop a greater capacity to support grain or seed production.
However, in Oklahoma and throughout the Southern Great Plains, yield potential and yield stability are not always the same thing.
The challenge facing producers across this region is that crops must balance the opportunity to maximize yield with the risk of running short on water during critical reproductive growth stages. As a result, the plant with the greatest theoretical yield potential is not always the plant that produces the most grain across a range of environmental conditions.
The Tradeoff Between Yield Potential and Yield Stability
Many may have heard of this difference. Even you if have not directly of these concepts, most in Oklahoma will be familiar with the trade-offs
Yield potential refers to the maximum yield a crop can achieve when environmental conditions are favorable, and resources are not limiting.
Yield stability refers to a crop’s ability to maintain performance across varying environmental conditions, including drought, heat stress, and erratic rainfall.
These two characteristics are often related, but they are not always aligned.
High vegetative growth frequently possesses greater yield potential because they can intercept more sunlight and support more reproductive structures. However, those same plants often require greater amounts of water throughout the season.
In contrast, plants with more moderate growth habits may have slightly lower maximum yield potential, but they often maintain more consistent performance when environmental stresses occur.
So the difference between excessive, adequate, and too low vegetative production is not consistent and is impacted by a part of the year not yet experienced.
For producers in the Southern Great Plains, where growing conditions can change dramatically from one season to the next, yield stability can be just as important as maximum yield potential.
Why More Growth Often Means More Yield Potential
The relationship between vegetative growth and yield begins with photosynthesis.
More leaves generally mean:
- Greater sunlight interception
- Greater photosynthetic capacity
- More carbohydrate production
- More potential reproductive sites
And when we are talking about farming, what we are often farming is the sunlight indirectly through the crops we are growing. Therefore, the higher amount of sunlight that can be captured, this higher potential yield can be.
In soybean, larger plants often produce more nodes and branches, creating additional locations for pod formation.
In grain sorghum, larger canopies can support greater grain production when moisture remains adequate through grain fill.
In corn, larger plants often contribute to greater kernel production and kernel weight under favorable conditions.
Because of these relationships, management practices that encourage vigorous growth are frequently associated with high yield environments.
The key phrase, however, is under favorable conditions.
The Hidden Cost of Large Plants
Every leaf that captures sunlight also loses water.
As plant size increases, so does transpiration demand. Larger plants require more water simply to maintain normal physiological activity.
This creates a challenge in many Oklahoma production environments.
Rainfall is often adequate during early vegetative development, allowing crops to establish large canopies and accumulate substantial biomass (often during the months of April and early May). However, the period from flowering through grain fill frequently coincides with:
- Higher temperatures
- Greater evaporative demand
- Less reliable rainfall
- Increasing soil moisture depletion
This can be a two-fold issue. One, higher vegetative production early could have utilized and drained total surface and subsurface moisture, which is now not available during reproductive growth. However, it also increased daily moisture demand. This can result in with similar soil moisture and rainfall, a smaller plant will have a lower moisture demand than a larger plant.
The consequence is often a reduction in grain or seed production precisely when yield is being determined.
Soybean: A Classic Example
Soybean perhaps provides the best illustration of this concept.
When moisture is abundant, larger soybean plants can be extremely productive. Additional nodes and branches create opportunities for greater pod production, and large canopies intercept significant amounts of sunlight.
However, soybean also possesses one of the longest reproductive periods among major summer crops.
A soybean crop must successfully retain flowers, maintain pods, and fill seeds over an extended period. Water stress at any point during this process can reduce yield.
Large soybean plants often consume considerable amounts of water during vegetative growth. If drought develops during pod set or seed fill, those plants may experience:
- Increased flower abortion
- Increased pod abortion
- Reduced seed size
- Premature canopy senescence
In contrast, a more moderate-sized soybean plant may use less water during early development and preserve soil moisture for reproductive growth.
While that plant may possess fewer nodes or branches and therefore slightly lower maximum yield potential, it may be better positioned to maintain yield under stressful conditions.
Seeing this in practice
As shown in Figure 1, plant growth regulation substantially reduced soybean height compared to untreated plants. Three weeks after treatment implementation, regulated plants ranged from 5–10 inches shorter than untreated plants. These reductions in height were accompanied by fewer mainstem nodes, but plants compensated by producing more branch nodes and increasing canopy coverage. The response was relatively consistent across both growing seasons, demonstrating that soybean plants can modify their growth habit when mainstem development is restricted.
Figure 1. Impact of plant growth regulation (physical removal) on soybean plant height compared to untreated plants. Data were collected across the 2022 and 2023 growing seasons.
While reduced plant size altered canopy architecture, the impact on yield differed substantially between years (Figure 2). In 2022, when environmental conditions were generally favorable and resources were less limiting, plant growth regulation did not improve yield. In fact, yields were slightly lower than the untreated control. This response likely reflects the reduced yield potential associated with smaller plants, as larger soybean canopies often intercept more light, accumulate greater biomass, and support higher seed production when adequate moisture is available throughout the season.
However, the response was markedly different during 2023, when moisture became increasingly limiting later in the growing season. Under these conditions, regulated plants significantly outyielded the untreated plants. The smaller canopy likely reduced seasonal water use and delayed soil moisture depletion, leaving more water available during critical reproductive growth stages. In contrast, larger untreated plants developed greater vegetative biomass and therefore higher water demand earlier in the season. Although these larger plants possessed greater theoretical yield potential, they were more susceptible to late-season drought stress when water availability became limited.
These results illustrate an important principle for summer crop production systems in water-limited environments. Larger plants often possess higher yield ceilings because of their greater vegetative growth and capacity to capture resources. However, that same vegetative growth can increase transpiration demand and accelerate soil water depletion, increasing the risk of yield loss if drought develops later in the season. Smaller plants may not achieve the same maximum yield potential in favorable years, but they often provide greater yield stability by reducing water demand and preserving resources for reproductive development. Consequently, the optimal plant size is often a balance between maximizing yield potential and minimizing drought risk, particularly in environments such as Oklahoma where late-season moisture stress is common.
Figure 2. Impact of plant height regulation on soybean yield during the 2022 and 2023 growing seasons. Yield responses differed between years, highlighting the tradeoff between maximum yield potential and yield stability under water-limited conditions.
Lessons from Grain Sorghum
Grain sorghum offers another excellent example.
One reason sorghum has traditionally been viewed as a drought-adapted crop is its ability to regulate water use throughout the season. Traits such as leaf rolling, reduced transpiration, and stay-green characteristics help preserve plant function during grain fill.
Many of these mechanisms do not necessarily maximize growth early in the season. Instead, they improve the likelihood that the crop can complete grain development under stressful conditions.
This strategy may occasionally sacrifice maximum yield potential in highly favorable years, but it often improves yield stability across multiple growing seasons.
Managing for Consistency Versus Chasing Maximum Yield
One of the most important questions growers must answer is whether they are managing for maximum yield potential or maximum yield consistency.
In highly productive environments with irrigation or reliable rainfall, encouraging aggressive vegetative growth may be appropriate because water limitations are less likely to restrict grain fill.
In contrast, dryland production systems throughout much of Oklahoma often reward a more balanced approach.
The goal is not necessarily to produce the largest crop canopy possible. Rather, it is to produce enough canopy to efficiently intercept sunlight while preserving sufficient water to support reproductive growth later in the season.
Bigger Isn’t Always Better—Especially in Dryland Systems
This does not mean smaller plants are inherently superior.
A very small plant may lack sufficient leaf area to fully utilize available sunlight and may never achieve high yield potential regardless of rainfall conditions.
The ideal crop is rarely the smallest or the largest plant in the field.
Instead, the most successful crops are often those that achieve a balance between vegetative growth and resource conservation.
They develop enough biomass to support high levels of photosynthesis while avoiding excessive water consumption before reproduction begins.
Final Thoughts
Across Oklahoma and the Southern Great Plains, crop production is often a matter of managing risk as much as maximizing yield.
Larger plants frequently possess greater yield potential because they capture more sunlight and produce more biomass. However, that potential comes with increased water demand. When rainfall becomes limiting during flowering, grain fill, pod set, or seed development, those larger plants can become more vulnerable to stress.
Smaller or more moderately sized plants may not always produce the highest yields in ideal environments. However, they often provide greater yield stability because they conserve resources and maintain reproductive growth when environmental conditions deteriorate.
For soybean in particular, this tradeoff is frequently observed. The largest plants in July are not always the highest-yielding plants in October. More often, the most successful plants are those that balance growth with resource conservation, preserving enough water to support reproduction when it matters most.
In the Southern Great Plains, where late-season drought remains one of the greatest limitations to crop production, understanding the difference between yield potential and yield stability may be just as important as understanding yield itself.
Corn Leafhopper Detected in Southwest Oklahoma – What Growers Need to Know to Reduce Risk of Corn Stunt Disease
Maíra R. Duffeck: OSU Field Crops Extension Pathologist, Department of Entomology and Plant Pathology
Ashleigh Faris, OSU Field Crops Extension Entomologist, Department of Entomology and Plant Pathology
On June 5, 2026, the first corn leafhoppers of the year were detected in a corn field near Fort Cobb in Caddo County, Oklahoma. The insects were collected from grain corn by Dr. Maira Duffeck’s Row Crop Pathology team, and its identification was subsequently confirmed by Dr. Ashleigh Faris, OSU State Extension Entomologist for Cropping Systems.
The two corn leafhoppers specimens were collected from within the whorls of V6-stage corn plants during routine field scouting. Specimens were collected using a cordless vacuum for identification and documentation. In addition, one corn leafhopper was captured on a yellow sticky trap installed at the edge of the field. The trap has been monitored and replaced weekly since planting as part of ongoing surveillance efforts.
This 2026 detection occurred 18 days earlier than the first corn leafhopper detection reported in Oklahoma during 2025. Due to delayed planting associated with drought conditions, much of the corn across the state is currently at vegetative growth stages compared to this same time last year. This situation raises concerns about the potential transmission of corn stunt pathogens by corn leafhoppers.
Research outside of the U.S. has shown that corn plants are most susceptible to infection by corn stunt pathogens during the vegetative growth stages, from emergence (VE) through tasseling (VT). However, infection can also occur during the early reproductive stages. Early infection can result in significant yield losses because affected plants have a longer period to develop symptoms and experience reductions in growth and grain production.
It is not yet known if the corn leafhoppers detected in Oklahoma are carrying corn stunt pathogens, therefore growers should assume that any corn leafhopper has the potential to be infectious. Consequently, management efforts should focus on early detection and suppression of corn leafhopper populations, particularly in fields with corn at vulnerable vegetative growth stages. Regular scouting and timely management decisions will be critical for reducing the risk of corn stunt development during the 2026 growing season.
The Insect Identification
The corn leafhopper is a small insect, approximately 1/8 inch long (about the size of a grain of rice), with a yellow to tan body color. Adults are characterized by two small black spots surrounded by lighter-colored halos located between the eyes (Figure 1), as well as a clean face meaning there are no additional markings on the head or body. It is important to note that many leafhopper species also possess two spots between their eyes, however, these other leafhoppers will also have other dark marks on their head and/or face.
To distinguish corn leafhoppers from other leafhopper species, look for the combination of the two black spots with halos and the absence of additional markings. Corn leafhoppers do not have spots, stripes, or other markings on their wings, back, abdomen, face, or the top of the head (Figure 2). For mor information on how to distinguish the corn leafhopper from other commonly occurring leafhoppers see OSU e-Pest Alert EPP-25-24.
The immature or nymphal stage is wingless and resembles a smaller version of the adult. Nymphs may also lack the characteristic black spots and halos found on adults (Figure 3), making identification more challenging.
For additional information on corn leafhopper identification, biology, life cycle, and its role in transmitting corn stunt pathogens, see OSU E-Pest Alert EPP-23-17 and OSU e-Pest Alert EPP-25-29.
Scouting Tips and Guidance
Corn leafhoppers can be difficult to detect due to their small size, preference for hiding deep within the whorls of developing corn plants, and their rapid darting movement when disturbed. Because of these behaviors, effective scouting requires a combination of methods, including vacuum sampling, sweep net sampling, and direct visual inspection. Check the borders and edges of corn fields first as this is where most early migrators will be found.
During vegetative growth stages, plants should be carefully examined by inspecting the whorls, where corn leafhoppers often remain concealed (Figure 4 and 5). Individuals may be dislodged from the whorl using a cordless vacuum (Figure 6) or cordless leaf blower equipped with thigh high stockings to capture collected leafhoppers. Vacuum several whorls, randomly at the field borders, moving into the interior of the field.
Sweep net sampling is another useful scouting tool. When walking through corn rows, the net should be swept side-to-side in a figure-eight motion over the canopy and across plants on both sides of the row. After several sweeps, the net should be carefully closed, and contents slowly examined for the presence of corn leafhoppers. As the crop transitions into reproductive stages, sweep netting should be adjusted to target the lower portion up to through the upper and mid-canopy by sweeping up and down along the sides of the corn plants.
Visual inspection remains an important component of scouting throughout both vegetative and reproductive stages. In vegetative corn, focus on whorl inspection. As the canopy closes and plants reach reproductive stages, examine the underside of leaves where leafhoppers may congregate. Check the underside of lower leaves for nymphs. When entering a field, pause periodically to allow leafhoppers to settle, then slowly observe surrounding plants before moving forward.
In addition to the insects themselves, other indicators of corn leafhopper presence include honeydew deposits, which appear shiny and feel sticky, the development of black sooty mold growing on honeydew (Figure 7), and the presence of white or translucent cast skins (exuviae) resulting from molting (Figure 8).
Current Integrated Pest Management (IPM) Guidance for Corn Leafhoppers
Pre-planting and Planting Decisions
There are currently no known corn stunt resistant hybrids available on the U.S. market. In areas where volunteer corn is present, growers should remove it as this vegetation serves as a reproductive resource for the insect and a potential reservoir for corn stunt pathogens. When possible, growers are encouraged to plant corn early, as this will help reduce the likelihood of corn being planted when corn leafhoppers are present. In areas where corn leafhoppers will be present at planting, growers should use a high insecticide seed treatment containing Cruiser® Corn 1250 or Poncho® 1250 to allow for protection of early vegetative stages. Trials conducted by Texas A&M AgriLife Research and Extension indicate that 500 and 1250 rates of the insecticide seed treatments suppress corn leafhopper adults through V5 and suppress nymphs (or egg laying) at least until V10. The higher 1250 rates of insecticide seed treatment outperformed the lower 500 rates.
Scout for the Corn Leafhopper
Follow the scouting guidance outlined above to monitor for the insect. Due to the efficiency of corn leafhoppers in transmitting pathogens associated with corn stunt disease, no economic threshold has been established at this time. As a result, growers are encouraged to manage corn leafhopper populations when they are detected in the field.
At present, the exact corn growth stage at which scouting should cease is not known. Previous guidance suggested continuing scouting through the V8 growth stage; however, based on past observations by state Extension personnel, recommendations have been extended to encourage growers to continue managing corn leafhopper populations through the R1 or R2 growth stages. More research is needed to determine the cutoff point for insect management under U.S. crop production conditions.
Chemical Control Options
Results from foliar insecticide efficacy trials conducted in 2025 by Dr. Ashleigh Faris at Oklahoma State University, and by personnel at Texas A&M AgriLife Research and Extension, provide insight into current foliar management options for corn leafhopper.
In these studies, pyrethroid insecticides and dimethoate were largely ineffective against corn leafhoppers. Foliar applications of indoxacarb at 8 – 10 fl. oz./A rate and flupyradifurone at 7 fl. oz./A rate provided up to 14 days of suppression for corn leafhopper nymphs. Thiamethoxam and lambda-cyhalothrin at 10 fl. oz./A rate provided similar nymph suppression for 14 days. If applying a foliar insecticide prior to tassel, applicators should not use a non-ionic surfactant (NIS) as an adjuvant. An NIS applied pre-tassel, particularly mid to late vegetative stages (V6-VT) can result in arrested ear development which causes “baby” or stunted ears/cobs with reduced or absent kernels, underdeveloped husks, poor or absent silk emergence and reddish/purple leaves These symptoms can appear like corn stunt disease symptoms; however, confirmation of corn stunt disease pathogens can only be done through molecular testing.
When selecting an insecticide, growers should prioritize products that are not broad-spectrum and that are less disruptive to beneficial arthropods, to preserve natural biological control in the agroecosystem. Insecticide applications should only be made when corn leafhoppers are confirmed to be present in the field being treated. As with all pest management decisions, the insecticide label must be followed; the label is the law.
Integrated pest management (IPM) recommendations for corn leafhopper will continue to evolve as additional research becomes available under Oklahoma growing conditions. Growers are encouraged to stay updated through future OSU Pest e-Alerts and to follow Cropping Systems Extension Entomologist Dr. Ashleigh Faris (@OSU_crop_insects) and OSU Field Crops Pathologist Dr. Maira Duffeck (@osu.plantpath) on Instagram for ongoing updates on corn leafhopper and corn stunt disease distribution in the state and results from 2026 insecticide efficacy trials.
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