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The 2023 Oklahoma Wheat Harvest Begins

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Oklahoma Harvest Report by the Oklahoma Wheat Commission

Oklahoma Wheat Harvest had test cuttings with small deliveries last Thursday evening in Eldorado, OK. Rains over the Memorial Day weekend delayed producers from getting into the fields, but machines started moving across the Southern border of Oklahoma in many locations on Monday and Tuesday this week. Light rains and high humidity in parts of Southwest Oklahoma will make a slow start today, but producers are hopeful to get rolling in these locations by late this afternoon. All locations being reported this afternoon are reporting favorable test weights in all locations with ranges from 60-64 lbs. per bushel. Several locations are reporting 62-64 lbs. per bushel.
Moisture has been ranging from 12-13.5%, with most wheat being taken in at around 12.5%. Early yields being reported in Southern Oklahoma are ranging from the mid 20’s to low 40’s depending on location and management practices. Some high management intensive producers have reported a couple locations to be making in the mid 40’s with one report coming in at 55 bushels per acre. Most yields being reported are ranging from the low 30’s to low 40’s in Southern and South Central Oklahoma. Those regions are predicted to have the best overall crop conditions for Oklahoma this year. Protein has not been reported on most early samples throughout the region, although some locations have reported proteins ranging from 12.5% to as high as 15%.

Eldorado– Test weights on early wheat ranging from 60 to 63 lbs. per bushel. No yields reported on early cuttings.
Grandfield/Devol/Chattanooga– Test weights ranging from 62-64 lbs. per bushel. Moisture reported at 12.5% to 13%. Yields ranging mostly from 30 bushels to 40 bushels per acre.
Frederick– Test weights on early cuttings ranging mainly from 60 to 62 lbs. per bushel. Moisture was reported at 12.5% to 12.7% Yields ranging from the low 30’s to low 40’s on the wheat being harvested.
Tipton– This area suffered more from drought than other areas in South Central, Oklahoma. Yields are being reported from the low 20’s to low 30’s depending on location. Test weight has been lower on some fields, but the average for the region is 60 lbs. per bushel. Moisture was ranging from 12.5% to 13%.
Altus/Duke– Harvest has started in this area with great movement yesterday afternoon. Light rains and high humidity will make the start slower this afternoon. Test weights ranging from 60 lbs. to 62 lbs. per bushel. Early yields reported from the high 20’s to low 40’s.
Hobart/Gotebo– A couple loads have just been received in these locations. Test weights reported at 60 to 62 lbs. per bushel. Yields ranging from the mid 20’s to low 30’s. Early reports indicate this area has struggled harder with drought conditions.
Lawton– A couple loads have been taken in at Lawton. Test weight was 62 lbs. per bushel, no yields reported. Moisture was 13.5%.
Rocky/Sentinel– Samples have been received at these locations but nothing has been cut, producers were hoping to start late this afternoon or tomorrow.


Below, see the next 1-3 day rain prediction forecast models provided by the Oklahoma Mesonet. The next Oklahoma Harvest Report will be published on Monday, June 5, 2023, and a regional report will be published by Plains Grain Inc. on Friday, June 2, 2023

2023 OSU Wheat Variety Testing Plot Tours and Wheat Status

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Hello everyone, find below the complete schedule for the 2023 OSU Wheat Variety Trials plot tours and Field Days. We look forward to seeing you all there!

Note that times are subject to change due to environmental conditions. Please call your County Extension Office to confirm the date, time, and location.

Notes:
Abbreviations: DP = Dual-purpose, GO = Grain-only, IM =Intensive management, SM = Standard management
1 Meet at the Extension office
2 Meet at the plot, 1 mile north of Bill’s Corner on the east side of Hwy 177 at Knobhill.
3 Meet at fairgrounds for lunch, plot tour south of town afterwards
4 Meet at plot ¾ mile west of HWY 54 on Arapaho Road
5 Lunch at Wheeler Brothers, plot tour north of elevator afterwards
6 Meet at Ledbetter’s farm @ 9:30, field tour @ 10, lunch @ 12
7 Lunch at Wheeler Brothers, plot tour north of town afterwards
8 Meal at Brook Strader’s farm, plot tour afterwards

The plot maps for each location can be found on our website click here

Below are pictures from some of the variety trial locations from the end of March to early April. Wheat needs rain badly.

You can watch my latest interview with SUNUP TV on the following link: How is Drought Impacting the Wheat Crop?

Balko wheat variety trial on March 28, 2023. Photo: Tyler Lynch.
Hooker wheat variety trial on March 28, 2023. Photo: Tyler Lynch.
Alva wheat variety trial on April 6, 2023. Photo: Tyler Lynch.
Cherokee wheat variety trial on April 6, 2023. Photo: Tyler Lynch.
El Reno wheat variety dual-purpose trial on April 5, 2023. Photo: Tyler Lynch.

Mites in Wheat Fields

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Amanda de Oliveira Silva, Small Grains Extension Specialist

Areas of Oklahoma with dry conditions have begun to see some visible wheat injury due to brown wheat mite (Figure 1) and winter grain mite (Figure 2). Last week, Josh Bushong, OSU Northcentral Area Extension Agronomist, reported seeing fields with injury due to brown wheat mites in Alfalfa and Kingfisher counties (Figure 3). Later that week Tyler Lynch, the Senior Agriculturalist in the Small Grains Program also reported seeing wheat grain mites in our wheat plots at Alfalfa and Woods Counties.

Two common mites can injure wheat, the brown wheat mite and the winter grain mite. Producers need to remain alert so that they don’t mistake damaged wheat from small grains mites for drought or virus disease.

Figure 1. Brown wheat mite with oversummering egg

Brown wheat mite is small (about the size of this period.) with a metallic brown to black body and four pairs of yellowish legs (Figure 1). The forelegs are distinctly longer than the other three pairs. Brown wheat mites can complete a cycle in as little as 10-14 days. Oklahoma experiences multiple generations of brown wheat mites that usually peak in spring, and the last generation occurs in April. At that time, females produce a whitish egg that will over summer.

Figure 2. Winter grain mite with a kidney-shaped egg

Winter grain mite is small (about 1 mm long) with a dark blue to black body and four pairs of orange-red legs, and a small reddish spot on the top of its abdomen that can be seen under magnification (Figure 2). Winter grain mite eggs are kidney-shaped, and change from clear, to yellow to reddish-orange after several days. They are laid on leaf blades and stems or the roots near the crown. Besides wheat, many grasses serve as host plants, including barley, oats, ryegrass, and fescue. We typically experience two generations each year, a fall generation and a winter generation that cycles out in March.

Figure 3. Field infested with brown wheat mite. Photos taken by Josh Bushong at Kingfisher County on February 21, 2023.
Figure 4. Leaf stippling from brown wheat mite (left) and grain wheat mite (right) feeding. Photo on the right taken by Tyler Lynch at Alfalfa county on April 24, 2023.
Figure 5. Field infested with winter grain mite

Both mites feed by piercing plant cells in the leaf, which results in “stippling” (Figures 4 and 5). The leaves take on a characteristic brown-grayish or cast and could be mistaken for injury due to herbicide. These mites are more likely to cause injury in wheat stressed from lack of moisture or nutrients.

Figure 6. Winter grain mite hiding in residue

Threshold

Brown wheat mites are not light sensitive but are vulnerable to driving rains of more than 0.25 inches, which tend to reduce populations. Winter grain mites are more tolerant of rainfall but are very light sensitive and tend to avoid bright, sunny days and windy days, so adjust your scouting accordingly. It is best to scout for winter grain mites on still, cloudy days or early morning/late evening. On sunny or windy days, they hide under the soil surface (up to a couple of inches) or congregate under dirt clods (Figure 6). Both mites are associated with continuous wheat production. Research suggests that brown wheat mite can be economically treated when there are 25-50 mites per leaf in wheat that is 6-9 inches tall. An alternative estimation is “several hundred” per foot of a row. The best recommendation for winter grain mite is to treat when plants show visible injury, and there are still mites present.

Chemical control

Only a few insecticides include either mite species on their label. Work conducted by Dr. Gerald Wilde at Kansas State evaluated several insecticides for the control of winter grain mites. Of those registered for winter grain mites, the insecticide dimethoate (Dimethoate and other generics) is effective. Other pyrethroid insecticides, lambda-cyhalothrin (Karate, Warrior II, and its generics), gamma-cyhalothrin (Declare) and beta-cyfluthrin (Baythroid and its generics) are also effective for both mites, even if they are not specifically listed on the label.

Additional resources

Contact your County Extension office

For more information on these mites, consult fact sheet EPP-7093 Mites in Small Grains by clicking here. If you find active mite infestations in your field, consult fact sheet CR-7194 Management of Insect and Mite Pests in Small Grains for registered insecticides, application rates, and grazing/harvest waiting periods by clicking here.

Impacts of the current long-term drought extend beyond the wheat crop itself

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Amanda de Oliveira Silva, Small Grains Extension Specialist and Brett Carver, Wheat Breeder

Oklahoma farmers plant on average 4 million acres of winter wheat each year, making wheat the largest cash crop in the state. Depending on market conditions approximately 30-60% of Oklahoma wheat acres is grazed by stocker cattle during the winter months. Therefore, wheat plays a crucial role in the cattle industry as it is the primary source of cool-season forage to fall-weaned calves.

Producers intending to use wheat for grazing purposes begin planting wheat around early to mid-September. The optimal time for planting wheat in a dual-purpose system (i.e., wheat used for both grazing and grain production) in central Oklahoma is around mid-September. This maximizes forage production while minimizing yield losses from an earlier planting date. However, with the current dry conditions and lack of soil moisture to drive germination, the likelihood of having forage this year is severely reduced to non-existent.

The current drought conditions result in the loss of a grazing opportunity, which leads to a significant loss of income to OK and OK wheat farmers in the US Beef Industry.

Cattle on wheat pasture near Apache, OK December 2021.

If this drought is extended later into the fall, as weather predictions indicate, it will threaten OK wheat intended for grain production.
What does that mean?

Oklahoma is the 2nd largest producer and an important source of high quality hard red winter wheat (HRWW) in the US (USDA-NASS, 2022). HRWW is the main source of wheat used to make almost all types of bread consumed in the US and abroad (e.g., Mexico). Therefore, a drought that prolongs in October and November will again deprive OK wheat farmers from that source of income (i.e., grain) and the country’s access to a key source of bread wheat.

Research efforts have been made from OSU to test and develop resilient varieties and management practices adapted to changing climate. A history about this was shown on FOX 25 News yesterday morning (link below). A drought of this magnitude uniquely and negatively impacts Oklahoma’s farm economy in two commodities, wheat and beef. We will continue to pray for rain!

FOX 25 News story: Oklahoma wheat farmers devastated by heat conditions while scientists develop solutions

Pre-harvest sprouting damage in wheat

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Amanda de Oliveira Silva, Small Grains Extension Specialist

Pre-harvest sprouting is the onset of grain germination while still on the wheat head. Once wheat reaches physiological maturity, it can initiate germination if exposed to ideal moisture and warm temperatures for a few days. This is the case in some areas of Oklahoma that have received rainfall for several days after wheat has ripened. Genetics and environmental conditions are responsible for the differences in susceptibility to sprouting. Thus, wheat varieties differ in their resistance to sprouting (i.e., some are more prone to sprouting than others).

The occurrence of pre-harvest sprouting damage in the state has been low to moderate so far. But, due to the number of questions/calls I have received with the same concern in the past days, I thought I would share a few thoughts.

Can I use sprout-damaged wheat for seed?

It depends on several factors, but more importantly, is the level of sprout damage that has occurred. Grains that are swollen and with split seed coat, without visible root or shoot emerging from the seed, might still be viable to be used as seed. In this case, a germination test is warranted after harvest and before planting. Suppose the grain shows broken seed coat with visible roots and/or coleoptile. In that case, it should not be kept for seed because they will likely have reduced viability or not be viable at all (Picture 1).

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, the Extension Ag Educator at Washita County.

Will pre-harvest sprouting damage affect quality?

The extent to which pre-harvest sprouting grain will affect quality depends on the level of damage. Grain germination causes the production of alpha amylase, an enzyme that breaks down starch. As the level of sprout damage increases, this enzyme also increases, leading to an impairment of grain quality. Sprouted damaged grain can negatively impact wheat flour and baking quality by affecting mixability, crumb strength, loaf volume, etc.

Resources:

Contact your local county Extension office.

Storage and Use of Low Test Weight and Sprouted Wheat –  Factsheet BAE-1109

Acknowledgments:

Gary Strickland, Jackson County Extension Director and SWREC Regional Agronomy Specialist

Glen Calvert , Extension Educator Ag/4H at Washita County

Wheat Disease Update – 2 June 2022

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This article was written by Meriem Aoun, Small Grains Pathologist

Crown and root rot (Figure 1) was among the common diseases throughout the last two weeks of May. We observed this disease in multiple counties in Oklahoma including Cimmaron, Payne, Major, Texas, Beaver, Canadian, Kingfisher, and Alfalfa. Culturing from infected samples at the Plant Disease Diagnostic Lab at OSU showed that most samples were infected by Fusarium pseudograminearum. Fewer samples from Kingfisher, Alfalfa, Beaver, and Payne counties were infected by Bipolaris sorokiniana which causes common root rot. In these samples, Bipolaris Sorokiniana was often detected in combination with Fusarium pseudograminearum. Bipolaris Sorokiniana also caused spot blotch on the leaves in samples from Payne and Garfield counties.

Figure 1. Symptoms of crown/root rot on the winter wheat variety ‘LCS Atomic AX’ in a farmer field in Kingfisher, OK (Photo credit: Mike Johnson, Albaugh LLC).

In Morris (Okmulgee County, East Central OK) and on May 31, I observed high incidence of Fusarium head blight (FHB or scab) as shown in Figure 2. Bleached heads with salmon-pink color spore masses were observed (Figure 3). Precipitations during May (around flowering time of the crop) favored the development of this disease. In addition, corn, which is another susceptible crop, was grown last year in this field contributing to the increase of the fungus inoculum in the soil. The FHB fungus produces a mycotoxin called deoxynivalenol (DON) which contaminates grain, increasing the likelihood for discounts or rejection of entire grain loads at the point of sale. This high FHB incidence in Morris agrees with the forecast from the wheat scab risk tool (www.wheatscab.psu.edu/), which showed that Eastern Oklahoma had medium-to-high scab risk (Figure 4).

Figure 2. Symptoms of Fusarium head blight (scab) in a winter wheat field in Morris (Okmulgee County, Oklahoma).
Figure 3. Wheat head showing Fusarium head blight symptoms. Salmon-pink color on the spikelet corresponds to Fusarium spore masses (photo credit: Brian Olson, OSU Wheat Pathology Lab).
Figure 4. Scab risk map for the US based on six-day weather forecast (wheatscab.psu.edu, checked on June 2, 2022). Warmer red color corresponds to higher disease risk. Eastern Oklahoma had medium-to-high scab risk.

On June 1st, the OSU Disease Diagnostic Lab received a sample from Kay County showing dark chocolate chaff and tenacious glumes on the winter wheat variety ‘Green Hammer’ (Figure 5). I also observed these symptoms in other locations in Oklahoma including Balko (Beaver County), Lahoma (Garfield County), and Morris (Okmulgee County). These symptoms are triggered by environmental stresses such as drought and can be observed on the winter wheat varieties ‘Green Hammer’, ‘Bentley’, ‘Baker’s Ann’, and ‘Joe’.

Figure 5. Dark chocolate chaff and tenacious glumes on winter wheat in Lahoma, Garfield County, Oklahoma.

Oklahoma Wheat Harvest Moves Forward with Abrupt Halt After Untimely Rains

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Courtesy Oklahoma Wheat Commission

Oklahoma Wheat harvest made great strides in South Central and Southwest, Oklahoma over the Memorial Day weekend with producers getting started in regions as far north as Omega and Hennessey with some minor cutting being reported by Seiling.  Moisture has been challenging for producers in Central Oklahoma and variety selections made a difference on whether producers were able to get into the fields or not this past week in central Oklahoma. Rains have now delayed harvest from moving forward in all regions of Oklahoma that began on Tuesday evening.  Reports from across the state have been fairly consistent on yields being reported mainly in the mid teens to mid 20’s, across most Southern and Western regions.  The occasional yield of 30 to 40 bushels have been reported on non-grazed management intensive ground.  We have had one or two reports of some fields making 51 to 52 bushels per acre.  It is thought yields will be better as harvest moves further North and reports have trended higher on yields in Central, Oklahoma around the El Reno, Okarche, Kingfisher, Omega areas. Yields in these regions are mainly being reported in the mid 20’s to mid 30’s depending on the variety and management practices. Producers have made great strides down around Grandfield, Tipton, Altus, Fredrick, Walters with approximately half of the crop being reported as harvested.  Harvest is just beginning in the Chickasha and Apache regions with producers getting good starts.  Heavy rains in several areas of Southwest Oklahoma from Hollis, Tipton, Altus to Frederick last night will most likely have an impact on quality from here on out.  South of Altus it was reported that they received 3 inches at the OSU research station and East of Altus some areas received 6 inches of moisture in less than an hour.  Flash flooding happened in several places from Hollis, Tipton and Altus to Frederick. It was reported that a rail line was washed out in Headrick early this morning.  Several places have been without power in this region as of this morning, due to high winds that knocked down power lines.  While yields have been below average the quality of the crop up to this point has been extremely favorable.  All the data on quality was taken before the late Tuesday evening /early Wednesday morning rains, so producers are concerned what things will look like once they get back into the fields.  

Grandfield- Harvest is reported as 50% complete in this region.  Test weights before the rain have been 60 pounds per bushel or higher. Yields making from the mid teens to mid 20’s depending on variety and management. Protein reported from 11.5% to 12%, with some higher proteins reported between 14% and 17%

Devol- Harvest in this region reported at 45% complete. Test weights before the rain making 59 pounds per bushel or higher. (Average is still probably 60+ for this region before the rain.)  Yields being reported in the mid teens to low 20’s.  Some yields reported as low as 6 bushels per acre.  Protein ranging from 11.5% to 12%.

Chattanooga–  Harvest in this region reported at 45% complete.  Test weights reported at 60 pounds per bushel or higher with yields in the mid teens to low 20’s for the most part.  Proteins ranging from 11.5% to 12%.

Frederick- Harvest in this region is 50% complete. Test weights ranging from 59 to 62 pounds/bushel.  Proteins ranging from 10 to 13.5% range. Yields being reported from low teens to one coming in at 38 bushels per acre.

Granite/Lone Wolf/Altus/Duke- Harvest in these regions is reported at 40% to 50% complete depending on location.  Test weights in this region before the rains ranging from 59 to 61 pounds per bushel.  (More falling in the 60+ range).  Yields being reported from 7 bushels per acre to the mid 20’s depending on location. We did have a few yields making in the high twenties to mid 30’s but those reports were minimal.  Proteins ranging from 12% to 17%.  Proteins in the 14 to 15% range not uncommon in these Western corridors.

Apache- Wheat harvest was just getting started in this region at the time of this report on Tuesday afternoon.  Only a couple loads of wheat had been taken in.  No yields, protein and test weights were reported as it would not be a good representation of the area at this point in time.

Sentinel/Rocky- Test weights reported in the 59 to 61 pound per bushel range.  (Samples before the rains were more in the 60+ range.)  Producers did get rolling good in this region over the Memorial Day weekend, the crop has been reported as clean with not much dockage.  Yields being reported from 14 to 25 bushels per acre.  Proteins ranging from 11.5% to 15% depending on variety and management practices.

Okarche– Over the weekend and up until yesterday, producers were just getting a good start in this region.  Grain was being taken in South, West, East and North of Okarche.  Test weights have been reported as decent with most being 60 pounds per bushel or higher.  Yields have been reported from as low at 10 bushels per acre to some making in the mid 40’s depending on management and variety.  It is thought in  the region, most will be looking at averages in the mid 20 to high 20 range.  Proteins being reported from 11.5% to 12%.

Kingfisher/Omega-Test weights on the wheat from this area reported at 60 pounds per bushel or higher.  Yields ranging from the mid 20’s to the mid 30’s.  A couple reports of fields with intensive management making in the mid 40’s to as high as 50. Protein ranged from 11.5% to 12.5%

Hennessey- Wheat harvest was just getting started in this region at the time of this report on Tuesday afternoon.  No yields, protein and test weights were reported as it would not be a good representation of the area at the time of the report.

Seiling-Wheat harvest was just getting started in this region at the time of this report on Tuesday afternoon.  No yields, protein and test weights were reported as it would not be a good representation of the area at the time of the report.

Below see actual rainfall accumulations for the past 24 hours. (Please keep in mind some of the numbers reported in actual report are higher than what Mesonet is showing based on conversations with agricultural producers in the region).  Also please see the forecast for tomorrow along with the 7-day forecast provided by the Oklahoma Mesonet.  The next harvest report will be scheduled for Monday, June 6, 2022, please keep in mind predicted weather is showing rains across the state over the weekend so the report might not have much change if producers do not get back into the fields before that time.  

Wheat Disease Update – 19 May 2022

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This article was written by Meriem Aoun, Small Grains Pathologist

During my visit to wheat fields in Morris (Okmulgee County) on May 16, I observed multiple fungal and bacterial diseases. Wheat crop in Morris looked good and tall compared to other locations in Oklahoma (Figure 1). Morris got substantial amount of precipitation, which favored some fungal and bacterial diseases.

Figure 1. Winter wheat crop in Morris, Oklahoma was in good condition as of May 16, 2022 (Courtesy Dr. Amanda Silva).

Bacterial streak (on the leaf, Figure 2) and black chaff (on the head, Figure 3) were frequently observed on multiple winter wheat varieties including ‘Big country’ and ‘WB 4401’. Bacterial streak and black chaff are two phases of the same disease and are favored by humid and warm climate, which was the case in Morris.

Figure 2. Symptoms of bacterial streak on the winter wheat variety ‘WB 4401’ in Morris, Oklahoma (Courtesy Dr. Amanda Silva; May 16, 2022).
Figure 3. Symptoms of black chaff on glumes and neck (Morris, Oklahoma; May 16, 2022).

In Morris, I also observed Septoria leaf spot and tan spot in the lower and mid canopy, but nothing much on flag leaves. Septoria leaf spot was more common and found on varieties like ‘Skydance’ and ‘Crescent AX’ (Figure 4). Both diseases were also observed in the Stillwater Agronomy Research Station on OSU winter wheat breeding lines. In addition, spot blotch and powdery mildew were found in multiple experimental plots in Stillwater on susceptible winter wheat varieties and OSU breeding lines (Figure 5).

Figure 4. Septoria leaf spot symptoms on the winter wheat variety ‘Crescent AX’ in Morris, Oklahoma (May 16, 2022).
Figure 5. The black spots show symptoms of spot blotch whereas the white patches correspond to powdery mildew infection on an OSU winter wheat breeding line (Stillwater, Oklahoma; May 11, 2022).

Powdery mildew and leaf rust were observed in both Stillwater and Morris (Figure 6 and 7). As I previously reported powdery mildew was observed in multiple locations in Oklahoma since April whereas leaf rust was first observed this year in Oklahoma during the second week of May.

Figure 6. Leaf rust symptoms on the hard red winter wheat variety ‘Baker’s Ann’ (Morris, Oklahoma; May 16, 2022).
Figure 7. Symptoms of leaf rust (circular orange pustules) and powdery mildew (white patches) on the hard red winter wheat variety ‘Baker’s Ann’ (Morris, Oklahoma; May 16, 2022).

In addition to these foliar diseases, I observed some head diseases including sooty mold (black head mold) (Figure 8) in wheat fields in Morris, El Reno, and Stillwater. Humid conditions promote this disease on wheat heads. Often wheat that has been subjected to a stress such as freeze, root rot, or drought shows a greater severity of sooty mold than healthy wheat. I also observed loose smut (Figure 9) in Chickasha, Stillwater, and Morris.

Figure 8. Symptoms of sooty mold on winter wheat in Morris, Oklahoma (May 16, 2022).
Figure 9. Symptoms of loose smut on the winter wheat variety ‘WB 2158’ (May 3, 2022).

Wheat Disease Update – 28 April 2022

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This article was written by Meriem Aoun, Small Grains Pathologist

During April, the Plant Disease and Insect Diagnostic Laboratory at OSU received multiple wheat samples showing symptoms of streaking on the leaves. Leaf streaks were greenish yellow and parallel as shown in Figure 1. Enzyme linked immunosorbent assay (ELISA) on these samples from different wheat varieties were positive for wheat streak mosaic virus (WSM). WSM infected samples were from fields in multiple counties in Oklahoma including Payne, Blaine, Cimarron, Harper, Grady, and Garfield. A couple of samples that tested positive for WSM were also positive for high plains virus (HPV) and were from Harper and Blaine counties. Both WSM and HPV are transmitted by wheat curl mite. I also observed symptoms of barley yellow dwarf virus (Figure 2) in fields in Payne, Cleveland, and Grady counties.

Figure 1. Wheat streak mosaic virus symptoms on the wheat variety ‘OK Corral’ (Grady County, April 13, 2022).
Figure 2. Symptoms of barley yellow dwarf infection on the wheat variety ‘OK Corral’ in a farmer field in Cleveland County, OK (the photo was taken by Bradley Secraw, extension educator, at Cleveland County on April 26, 2022).

I also observed leaf spotting on the wheat variety ‘OK Bullet’ in the Stillwater Agronomy Research Station. Culturing from the leaves resulted in the identification of the fungi Bipolaris sorokinana which causes spot blotch and Parastagonospora nodorum which causes septoria nodorum blotch. Parastagonospora nodorum was also recovered from leaf spots on leaves of the variety OK Corral in Cleveland County.

Around mid-April, the OSU Diagnostic Lab received a wheat sample from the variety ‘Doublestop CL Plus’ from Blaine County. I examined the sample and I found that the infected plants were stunted and brown and showed weak root systems (Figure 3). Culturing from infected tissues identified Bipolaris sorokiniana which causes common root rot and Fusarium sp. which cause root, crown and foot rots. These fungi are favored by drought conditions in Oklahoma during the fall and spring. Dr. Silva and Gary Strickland also reported seeing root rot at Cotton county.

Figure 3. Common root rot and Fusarium root, crown and foot rots in a wheat sample from the wheat variety ‘Doublestop CL Plus’ (Blaine County, April 13, 2022).

Wheat Disease Update – 12 April 2022

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This article was written by Dr. Meriem Aoun, Small Grains Pathologist

During the first and second week of April, some wheat diseases appeared in Oklahoma. For example, in the Stillwater Agronomy Research Station, I observed high powdery mildew infection on the susceptible wheat variety ‘OK Bullet’ (Figure 1). Similarly, Bradley Secraw (Extension educator at Cleveland county; March, 31, 2022) found little powdery mildew infection on the variety ‘OK Corral’ which is moderately resistant to this disease. In Stillwater and on April 11th, I observed initial stripe rust infection on OK Bullet (Figure 2). Also recall in my previous update of 25-March, I indicated seeing little stripe rust infection in Jackson county. Therefore, I encourage growers to start scouting their fields for these diseases, especially if they are growing susceptible varieties. We will continue to monitor these diseases as we approach flag leaf stage and provide recommendations.

Figure 1. Powdery mildew infection on the susceptible wheat variety ‘OK Bullet’ in Stillwater, OK (April, 11, 2022)

In the Stillwater Agronomy Research Station, I also observed barley yellow dwarf virus (BYD) symptoms on the susceptible wheat variety ‘Pete’. The symptoms appeared as yellow, red/purple discoloration on the leaves as shown in Figure 2. This virus is transmitted from plant to plant by cereal aphids. Enzyme linked immunosorbent assay (ELISA) on a symptomatic sample from Pete was positive for two BYD strains; BYD strain 2 (BYDV-PAV) and cereal yellow dwarf (CYDV-RPV).

Figure 2. Barley yellow dwarf virus symptoms on the susceptible variety ‘Pete’ in Stillwater, OK (April, 5, 2022).

In Stillwater, I observed yellowing on the wheat variety ‘Lonerider’. Older leaves were completely chlorotic (Figure 3). Laboratory diagnosis of a sample using ELISA was positive for wheat streak mosaic virus (WSM) which is transmitted by wheat curl mite. This disease is an issue in our region as many wheat varieties growing in Oklahoma are susceptible to WSM.

Figure 3. Symptoms of wheat streak mosaic virus on the susceptible wheat variety ‘Lonerider’ in Stillwater, OK (April, 5, 2022).