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David Marburger

David Marburger

Since April 2016, I have served as the Small Grains Extension Specialist at Oklahoma State University. My research and extension efforts focus on delivering science-based recommendations in order to increase small grains production and profitability for stakeholders throughout Oklahoma and the southern Great Plains.

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Oklahoma Wheat Harvest All But Complete Except the Panhandle Regions

Report by the Oklahoma Wheat Commission:

 

The Oklahoma wheat harvest is complete in most areas from the Oklahoma/Texas border to the Oklahoma/Kansas border. A few machines are still moving in Northern Oklahoma but harvest in all areas of this region should be completely finished by the end of the week. In the Panhandle region harvest is in full swing with producers working on the dryland harvest. We have had some reports that harvest on the irrigated wheat is starting to happen around the Hooker area, but no yields have been reported on the irrigated wheat. Dryland wheat in the Panhandle is averaging in the mid 20’s to low 30’s depending on location for the most part.

 

Test weights on the dryland wheat in the Panhandle is averaging about 60 lbs./bu. Proteins on the dryland wheat in this region has been surprising with many reports coming in at 12% or higher, but elevator managers are concerned those numbers will be lower once we get into the irrigated wheat. Proteins across Oklahoma are being reported in the 10.5 to 11.5% range. Harvest has moved faster than expected in a lot of locations since producers have opted to go with other crops or have grazed out in other areas. The decrease in planted wheat acres has caught the attention of many elevator managers in the state. In many places the yields were above average but with the lower planted acres, the amount of bushels taken in at all locations across Oklahoma have been way down from last year. Many elevator locations in Southwest Oklahoma took in 50 to 60% of the bushels they had last year. As harvest progressed further North many elevator locations in that region took in 60 to 70% of the bushels they received last year.

Oklahoma Wheat Harvest Continues while Moving North

Report by the Oklahoma Wheat Commission

Wheat harvest continues in Oklahoma moving full speed ahead in all regions. Along the Oklahoma Texas line many locations are reported to be 97 to 99% complete. Elevators in South Central Oklahoma are reporting harvest to be 75 to 90% complete depending on the location, while parts of Central Oklahoma are 95% harvested. As harvest has moved forward in Northern Oklahoma some locations have reported harvest to be 75% complete along the I-35 corridor. In Northwest Oklahoma reports of harvest completion are ranging from 35% to 50% depending on location.

In some locations producers were able to get back into the fields last Tuesday, but in all areas since Thursday because of the open weather, producers and custom harvesters have been able to take advantage of getting the crop out in record speed since they have started rolling. Test weights across the state have dropped in most locations, but as of today many locations are still reporting 60 lbs./bu. averages. Yields across the state have been ranging all over the board depending on the management, heavy rains and hail damage. Across Southwest Oklahoma, we have heard of yields ranging from the mid teens to the mid twenties, with also better yields in some areas of this region reported to be in the mid 30’s to mid 40’s. The same is holding true for Central and Northern Oklahoma. As we have moved into Northern Oklahoma, we have been hearing higher yields in the mid 40’s to 50’s with many reports of wheat in some locations to be making anywhere from the mid 60’s to mid 70’s.

Harvest has moved faster in Southern Oklahoma due to many of the wheat acres going into cotton. We are also hearing reports in Northern Oklahoma that even though the yields are high the number of bushels will not be taken in because of the other summer crops that producers are opting to go with right now. Proteins across Oklahoma are being reported in the 10.5 to 11.5% range. We have had some reports on some proteins as high as 13% in North Central Oklahoma.

 

Report by Locations:

Grandfield – Harvest reported to be 99% complete. A lot of the wheat in this region was heavily grazed. Due to the heavy rains and hail, they are seeing yield reports making in the mid 20’s to mid 30’s with the occasional 40+ yield. Test Weights reported from 59 to 61 lbs./bu.

Chattanooga – Harvest reported to be 99% complete. A lot of the wheat in this region was heavily grazed and due to the heavy rains and hail, they are seeing yield reports making in the mid 20’s to mid 30’s. Test weights reported from 59-61 lbs./bu.

Lone Wolf – Harvest in this region reported to be 90% complete. The test weights in this region have been averaging 59- 60 lbs./bu. Yields in the region ranging from the mid 20’s to the mid 30’s, with reports of some wheat making better than 40 bushels per acre.

Hobart – Harvest in this area is reported to be 85% complete. The test weights in this region have been averaging 58-60 lbs./bu. Yields in the region ranging from the mid 20’s to the mid 30’s with some wheat in the region reported to be making in the mid 40’s.

Granite – Harvest in this region reported to be 90% complete. Test weights in this area have been doing remarkably well, ranging from 60 to 64 lbs./bu. Yields in this region also reported to be higher with reports of a lot of wheat making in the mid 40’s to mid 50’s.

Hinton – Harvest in this area is reported to be 75% complete. Test weights in this region have been averaging 58 to 60 lbs./bu. Yields have been reported all over the board from as low as 10 to as high as 60. A lot of wheat in this region was reported to be making in the mid 30’s to mid 40’s.

Okarche – Harvest in this region is reported to be 95% complete. Test weights in this region were reported to be averaging 60lbs./bu. Yields in this area also have been reported all over the board from as low as 10 to as high as 50. A lot of reports of wheat in the region was stated to be making in the mid 30’s to mid 40’s as an average.

Hennessey – Harvest in this region is reported to be 75% complete. Test weights in this region have been lighter due to the heavier rains, this area for the most part is looking at 58 to 59lbs./bu. average. Yields in the region are reported all over the board depending on the weather and management practices. A lot of wheat was reported to be making in the mid 30’s to mid 40’s, while some yields were lower due to hail.

Perry – Harvest moved quickly over the weekend in this region and elevator managers are calling it 75% complete. Test weights have gotten lighter with the rains. Currently the average test weight for the region is 59lbs./bu. Yields have been reported all over the board, with reports as low as 10 on hail damaged wheat, and other reports with yields as high as 60. We have had a lot of reports of wheat making in the mid 40’s to mid 50’s in this region.

Braman – Harvest in this region is just getting started and would be considered 30% complete. Test weights in the region are averaging 59 lbs./bu. Yields in this region are reported from the mid 30’s to the mid 50’s.

Cherokee – Harvest in this region is approximately 50% complete. Test weights in this area have been reported all over the board and have been lowered due to the rains from last week. The area is still hoping for a 58 to 59lbs/bu. average on test weight, although lower weights have been reported. Yields in this region have been all over the board with reports on damaged wheat to be making in the mid 30’s, while higher yielding wheat has been reported to be making in the low to mid 70’s.

Alva – Harvest in this region is reported to be 35 to 40% complete. Test weights for the region are averaging 58 lbs./bu. Yields have been reported all over the board from the mid 20’s to as high as 60 bushels per acre.

Shattuck – This location just got started with harvest yesterday. They reported to take in 60,000 bushels at CGB at this location. Test weights were ranging from 62 to 63 lbs./bu. No yields have been reported from the region, but it is reported that yields will range from the mid 20’s to mid 40’s for the most part.

Hooker – No wheat has been taken in at this location in the Panhandle. It is predicted that harvest will begin towards the end of the week at this location.

Save the date for the 2017 Oklahoma Crops Conference!

2017 OK Crops Conference - Save the date

Oklahoma Wheat Harvest Progressing from South to North Amidst Rains

Report by the Oklahoma Wheat Commission

Wheat harvest continues to move from Southern Oklahoma with locations on the Oklahoma/Texas State Line reporting to be 95 to 97% complete, while harvest is just starting in locations on the Oklahoma/Kansas state line.  Rain has hindered harvest from progressing across the state this past weekend with rain showers also impacting producers last night in many locations across the Western half of Oklahoma.  The wet conditions with high humidity has made it difficult for producers to get early starts cutting even where the ground was dry enough to carry the combines yesterday afternoon.

Rain averages last night were reported by many locations to be anywhere from .1 inches to over 2 inches depending on the location with the Mesonet reporting only .04 inches in some parts of Oklahoma on the Oklahoma/Texas line.  Over the weekend some parts of Western Oklahoma had locations that received anywhere from 4 to 7 inches of moisture right before the wheat was ready to cut.  Test weights have dropped in many areas across Oklahoma, and some producers are concerned they will have lost another pound after the rains last night.  Fortunately, the test weights were starting out this harvest extremely high. Many elevator locations, as of today, are still hoping for a 60 lbs./bu. average, with some locations starting to report test weights ranging in the 58 to 59 lbs./bu. range. It has been stated that we have two crops in the field since many producers opted for later plantings in Central and Northern Oklahoma based on other crop rotations they have been using. This, and the cooler temperatures, have been helpful on test weight up to this point for the crop that is left in the field to be harvested.  Yields across the state have been ranging all over the board depending on management, heavy rains and hail damage.  Across Southwest Oklahoma, we have heard of yields ranging from the mid teens to the mid twenties, with also better yields in some areas of this region reported to be in the mid 30’s to mid 40’s. The same is holding true for Central and Northern Oklahoma.  As we have moved into Northern Oklahoma, we have been hearing higher yields in the mid 40’s, with some reports of wheat being in the mid 50’s. Many elevator managers are hopeful we will have later wheat coming in with yields higher if we can just get ahead of the rains.  One thing impacting the amount of bushels being taken in at all locations is the amount of wheat acres that have gone into other crops; whether it be cotton, canola, sesame, soybeans or hay.  We have also seen acreage decline for larger amounts of the crop being grazed out early this spring.  In parts of Southwest Oklahoma, elevators plan on taking in 50 to 60 percent of the bushels they would normally take in based on the acres that are being planted to cotton.  Elevators in North Central Oklahoma have been making the same comments based on producers opting for other options with canola and soybeans.

 

Report by Locations:

Grandfield-Harvest reported to be 95 to 97% complete  A lot of the wheat in this region was heavily grazed.  Due to the heavy rains and hail they are seeing yield reports  making in the mid 20’s to mid 30’s with the occasional 40+ yield.  Test Weights reported from 59 to 61 lbs./bu.

Chattanooga- Harvest reported to be 95 to 97% complete.  A lot of the wheat in this region was heavily grazed and due to the heavy rains and hail, they are seeing yield reports making in the mid 20’s to mid 30’s. Test weights reported from 59-61 lbs./bu.

Lone Wolf- Harvest in this region reported to be 85% complete.  The test weights in this region have been averaging 60 lbs./bu. Yields in the region ranging from the mid 20’s to the mid 30’s with reports of some wheat making better than 40 bushels per acre.

Hobart- Harvest in this area is reported to be 85% complete. The test weights in this region have been averaging 60 lbs./bu. Yields in the region ranging from the mid 20’s to the mid 30’s with some wheat in the region reported to be making in the mid 40’s

Granite- Harvest in this region reported to be 85% complete. Test weights in this area have been doing remarkably well, ranging from 60 to 64 lbs./bu.  Yields in this region also reported to be higher with reports of a lot of wheat making in the mid 40’s to mid 50’s

Rocky- Harvest in this region is reported to be 50% complete. The rains over the weekend and last night have producers in this region at a standstill, with hopes they will be able to get back into the fields hopefully on Friday.  Test weights in this region are ranging from 58 to 60 lbs./bu. Prior to the rains, a lot of wheat was taken in at this location with test weights ranging from 62 to 64 lbs./bu. Yields in this region are reported to be making in the mid 30’s for the most part.

Sentinel- Harvest was progressing yesterday with combines planning to continue today since the rains were missed last night. Test weights in this region reported from 59 to 60 lbs./bu.   Yields have not been reported since harvest in the area is just beginning.

Greenfield- Before Friday, test weights in the region were coming in extremely high with most weights ranging from 63 to 64 lbs./bu.  It is estimated 1/3 of the crop is harvested in this area. The rains over the weekend and last night have placed harvest at a standstill with the hopes producers will be able to get back into the fields by Friday at the earliest.  Some wheat was harvested in the region late yesterday afternoon with test weights ranging from 59 to 60 lbs./bu. Yields in the region reported to be making anywhere from the mid 20’ to the mid 50’s.

Kingfisher- After the weekend rains, producers started harvesting again in parts of this region yesterday afternoon.  In many parts of this area the rains went West so producers will be harvesting in the area this afternoon as well.  Test weights, as of yesterday, were ranging for the most part, from 59.5 to 60 lbs./bu. Yields are reported all over the range from the mid 20’s to the mid 40’s, depending on the rains and hail damage.  Some reports indicate a few producers had some yields in the mid 50’s before the rains this past weekend.

Helena–  Harvest in this region has started with a couple of producers cutting. Test weights on the 3,000 bushels that has been taken in is reported in the range of 60 to 61 lbs./bu. No yields from the area have been reported.

Pond Creek- Harvest has just begun in this region.  Test weights are ranging from 58 to 61 lbs./bu. Producers in this area are hoping to get moving at full speed this afternoon.  No yields have been reported on early cuttings, but some of the wheat in this area still looks very favorable.

Tonkawa- Harvest in this region is just getting started. Test weights in the region are averaging so far 60 to 61 lbs./bu.  One producer figured he was making in the mid 50’s.  Indications are a lot of the wheat looks favorable in this region, although many acres within the area also had significant hail damage, depending on where the storms hit.

Burlington- Harvest just started in this region yesterday. Some producers will most likely cut this afternoon, while others will be out of the field for the next couple of days, due to the rains last night.  30,000 bushels have been hauled into Burlington so far.  Test weights are decent with a 60lbs./bu. average reported. No yields have been reported, but producers are hopeful the yields  will be decent if they can get into the fields without more rain.

Shattuck- No wheat has been taken in at this location, but producers are hopeful harvest will get started in this region by the weekend.

Hooker-  No wheat has been taken in at this location in the Panhandle. The cooler temperatures in the region have slowed the ripening.  Many producers think harvest in the area is at least 6 to 10 days away.

Wheat Harvest Progresses in Southwest and Central Oklahoma Over Memorial Day Weekend

Report by the Oklahoma Wheat Commission

 

Wheat producers across Southwest and Central Oklahoma had combines moving at full speed over the Memorial Day weekend. Yields in parts of Southwest Oklahoma were lowered by heavy rains and hail that passed thru the state over a week ago. In other places the crop has been fairing with decent yields and high test weights up to this point.  Elevator managers have been reporting the significant loss of wheat acres to be impacting the speed of harvest in Southwest Oklahoma. This is making the season seem to go much faster. Several managers have been reporting they expect to take in 50 to 60 percent of the bushels in this region they normally take due to the increase in planted cotton acres.

In Central Oklahoma the crop harvest is also progressing with decent yields and test weights reported in most areas. Producers also have had issues with hail damage West and East of Kingfisher. Many elevator managers have stated we have a decent quality crop overall, if we can just get to it before we receive more rainfall. The 7 day forecast of more predicted rains have many producers concerned about what lies ahead for this harvest season all across the state. Proteins across Texas on up into central Oklahoma are being reported in the 10.5 to 11% range.

Grandfield-Harvest reported to be 65% complete. A lot of the wheat in this region was heavily grazed and due to the heavy rains and hail they are seeing a lot of yield reports to be making in the mid 20’s to mid 30’s with the occasional 40+ yield. Test Weights reported from 59 to 61 lbs./bu.

Chattanooga- Harvest reported to be 50 to 55% complete. A lot of the wheat in this region was heavily grazed and due to the heavy rains and hail they are seeing a lot of yield reports to be making in the mid 20’s to mid 30’s. Test weights reported from 59-61 lbs./bu.

Lawton- Harvest reported to be 50% complete. The wheat in this area has been having better yields ranging from the mid 20’s to the mid 40’s. Test weights in this area are averaging 61 lbs./bu.

Altus- Harvest in this region reported to be 60% complete. The test weights in this region have been averaging 60 to 63 lbs./bu. Yields in the region reported from the mid 20’s to the mid 40’s. Overall the visual quality is reported to be very favorable from this region.

Lone Wolf- Harvest in this region reported to be 45% complete. The test weights in this region have been averaging 60 lbs./bu. Yields in the region ranging from the mid 20’s to the mid 30’s with reports of some wheat making better than 40 bushels per acre.

Clinton- This region is just getting started as of yesterday. No yields have been reported but the test weights on what has come in so far is averaging 60 lbs./bu.

Rocky- Harvest in this region has been progressing slowly. Yesterday, was considered to be a decent day for the area with more wheat reported to be coming in. Test weights reported at 60 to 61 lbs./bu. Yields reported to be making in the mid 30’s for the most part.

El Reno- Harvest in this region has been moving steady over the Memorial Day weekend, with producers just getting a good start in this area. Yields in the region from early reports indicate the crop is doing well coming in with a lot in the range of the mid 40’s.  Test weights reported to be making anywhere from 61 to 63.5 lbs./bu.

Kingfisher-Harvest is just beginning in this region with a few reports of wheat harvest beginning to start around Loyal and Omega. Test weights in the region being reported in the 58 to 63 lb./bu. range. Yields have been ranging all over the board in this region, with reports of wheat making anywhere in the mid 20’s to mid 40’s for the most part. A few reports that some producers in the region have been making in the mid to high 50’s.

Wheat Disease Update – May 27, 2017

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

Department of Entomology & Plant Pathology

Oklahoma State University – 127 Noble Research Center

405-744-9958 – bob.hunger@okstate.edu

 

 

This past week I traveled and looked at wheat in north-central/northwestern OK at Alva and Cherokee, as well as wheat in the panhandle.  I also looked at wheat here around Stillwater and in central OK near Kingfisher/Okarche (30-35 miles northwest of OKC).  Wheat in central OK and around Stillwater is or quickly will be ready for harvest, weather permitting.  Wheat across northern OK (Cherokee and Alva) was quickly approaching maturity, but kernels were still soft and some green was still present in stems/heads.  Wheat in the panhandle ranged from ¼ to full kernel, with stems and leaves still quite green in many varieties.

 

Leaf rust is still active in the panhandle area, and samples testing positive for Wheat streak mosaic virusHigh plains virus, and Barley yellow dwarf virus continue to come to the Diagnostic Lab.  In some fields I saw (and in talking to producers), it is difficult to see where the mites/virus originated, but grassy weeds and perhaps volunteer crops such as sorghum or corn may be the most likely source.  For more information on mite-transmitted wheat viruses such as WSM, please see OSU Fact Sheet EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) available at http://wheat.okstate.edu/wheat-management/diseasesinsects/EPP-7328.

 

One abiotic disease (a disease not caused by a pathogen) that is being reported is a head darkening or head melanism (Figure 1).  Reports of this darkening have come from southwestern and central OK, as well as from northern OK around Blackwell/Tonkawa/Ponca City.

 

Figure 1.  Head darkening (melanism) as seen in the Lahoma variety trial in late May.

fig1afig1b

Although this darkening has been observed in several varieties, it seems to be most noticeable in the variety Bentley.  Dr. Carver had noticed a head darkening in Bentley prior to its release, but apparently environmental factors this year have caused it to be expressed more strongly than in years prior.  One of the parents of Bentley is TAM 303, which was developed by Dr. Jackie Rudd at Texas A&M University.  Dr. Rudd sent the following information:  “Bentley has the same “fluorescent” green glumes early and dark red/brown chaff color at maturity as TAM 303 which is one of it’s parents. TAM 303 and many of it’s descendants normally have 1-2% of near black heads that look like your photos. Most are sterile or have a few shriveled seeds. This is not an impurity, and is expressed more in some environments than others. It is sometimes spotty in a field and sometimes scattered throughout. Our take on it was that it was just a concentration of the unique TAM 303 glume color in sterile heads- whatever might have caused the sterility. Freeze related sterility is a common culprit for us. For us, almost all TAM 303 derived lines that have the fluorescent green heads, would also have some of these black heads if we had sterility.”  Dr. Carver has indicated that during the development of Bentley, he took seed from dark heads and planted that seed to see if there was any effect on the next generation of wheat plants.  He did not see any effect on the next generation either in wheat yield or in the incidence of dark heads.  However, in some environments seed from darkened heads may not be as plentiful or “full” as seeds from non-darkened heads (Figure 2).

 

Figure 2.  Seed taken from a dark and non-dark head of Bentley wheat.

fig2

In summary, this head darkening that has been observed in Bentley and other varieties appears to affect seed yield and kernel filling, and is related to the genetics of the variety that is induced by an unknown stress or combination of stresses.

Wheat Harvest Starts Moving Again in Southwest Oklahoma

Report by the Oklahoma Wheat Commission

 

Early reports of wheat harvest beginning in Southwest Oklahoma show the crop to be coming in with decent yields and test weights. Although only 4 percent of the crop is speculated to be cut out in Oklahoma, producers are hopeful those numbers will change over the Memorial Day weekend. Test weights on wheat from most regions is reported in the 59 to 62 lbs./bu range with the occasional 63 to 64 lbs./bu still being reported since the rains this past week. Crop yields are reported to be in the mid 20’s to mid 40’s depending on whether the crop was grazed heavily. Many producers around the Chattanooga and Walters area have reported great yield loss due to the hail storms that passed thru the area earlier in the week. Samples have even been submitted as far North as Okarche, Oklahoma at 14% moisture with the hopes that some will be harvesting in that area of Central Oklahoma later this afternoon. Early reports on protein from Central Texas to the Oklahoma/Texas border have been showing averages of 10.5 to 11.5%, although we have had reports of higher proteins coming in at 13.5% as harvest has progressed North. Producers and custom cutters are hoping Mother Nature will cooperate with them over the weekend and are concerned about potential upcoming storms predicted for later next week!

Wheat harvest has begun in Oklahoma

Report by the Oklahoma Wheat Commission

 

Harvest in Oklahoma has begun on the Oklahoma/Texas border with combines rolling along the Red River down around Grandfield and Eldorado. It has been reported that over the past couple days in the Grandfield area they have taken in approximately 30,000 bushels. Test weights have been averaging 63 to 65 lbs./bu, with yields ranging from the low 20’s to mid 40’s. In Eldorado, some early wheat was harvested as early as last Thursday but combines have started moving at a faster speed within the last couple days. It was reported in this area that approximately 50,000 bushels have been hauled to town. Test weights in this area are ranging from 60 to 61.5 lbs./bu, with occasional loads coming in higher than that. Yields in the region also ranging from the mid 20’s to mid 40’s. Protein from the region is not being reported until a more accurate report can be given when more bushels come in. It was reported that one load was received in Frederick last night, but based on high moisture, it looks like harvest in this region is still a couple days away. Producers across the state are hoping the predicted storms this week do not damage or pro-long the beginning of harvest. The anticipated forecast from the Oklahoma Mesonet on Tuesday, May 16 at 9:00 a.m. for the coming week currently looks like getting into the field is going to be a challenge over the next few days.

Wheat Disease Update – May 15, 2017

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

Department of Entomology & Plant Pathology

Oklahoma State University – 127 Noble Research Center

405-744-9958 – bob.hunger@okstate.edu

 

 

This past week and today, I traveled and looked at wheat in central OK near Kingfisher (35 miles northwest of OKC) and near El Reno (20 miles west of OKC) as well in north-central/northwestern OK near Lahoma (15 miles west of Enid), Alva and Cherokee.  Wheat was mostly in the soft to medium dough stage, but only about full kernel to milk in northern OK (Alva and Cherokee).  In central OK, flag leaves were mostly gone, primarily due to rust (both stripe and leaf, but mostly leaf).  In the more northern areas (Lahoma, Alva, and Cherokee), there was still green flag leaves on varieties with resistance to leaf/stripe rust.

 

Samples testing positive for Wheat streak mosaic virus, High plains virus, and Barley yellow dwarf virus continue to come to the Diagnostic Lab, with samples now coming more from northwestern OK and the panhandle.  For more information on mite-transmitted wheat viruses such as WSM, please see OSU Fact Sheet EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) available at http://wheat.okstate.edu/wheat-management/insectsdisease/EPP-7328.

 

 

Reports/excerpts of reports from other states:

Dr. Erick DeWolf, Wheat Extension Pathologist, Kansas State University, May 12, 2017:  “Stripe rust and leaf rust were rapidly increasing in incidence and severity in parts of central Kansas this week. Stripe rust and leaf rust became established in the upper canopy of wheat in south central Kansas a few weeks ago. Observations this week indicate that stripe rust has increased in severity in many fields of susceptible varieties that were unprotected by fungicides. In some cases, more than 30 percent of the flag leaf area has been damaged by the disease. Leaf rust has also moved to the upper leaves on susceptible varieties in the south central region.

 

Stripe rust and leaf rust were also reported in additional areas of the state this week with many new reports of the disease in middle canopy in west central and northwest regions of the state. There are a few reports of stripe rust moving to the upper leaves in these areas also, but for the moment this seems to be rare.”

Wheat Disease Update – May 6, 2017

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

Department of Entomology & Plant Pathology

Oklahoma State University – 127 Noble Research Center

405-744-9958 – bob.hunger@okstate.edu

 

Nearly all of the wheat I saw this past week was along a line for about 100 miles west of Stillwater. Wheat around Stillwater is at the milk to soft dough stage. Wheat west of Stillwater ranged from full kernel to full kernel-milk. In this area, I saw both good and bad wheat. Much of the bad wheat I saw had been hit with wheat streak mosaic (WSM). To date, the Plant Disease and Insect Diagnostic Lab (Ms. Jen Olson, Director) has assessed about 82 wheat samples from 19 counties for Wheat streak mosaic virus (WSMV), High plains virus (HPV), and Barley yellow dwarf virus (BYDV; PAV strain). These 19 counties are located west of Stillwater and mostly west of I-35. Of these 82 samples, 56 were positive for WSMV, 11 were positive for HPV (all 11 co-infected with WSMV), and 42 were positive for BYDV. Four of the samples were positive for all three viruses. These figures indicate the severity of wheat viruses in Oklahoma this year. Reports from other states indicate this problem (mite transmitted viruses such as WSM) is just as severe up through the central plains. The cool, wet weather we have had can mitigate the effects of WSM and BYD and help infected plants to continue to mature and finish. This would be especially true for plants/fields that were infected in the spring. However, yield and test weight will be affected especially if wheat was infected in the fall. For more information on mite-transmitted wheat viruses such as WSM, please see OSU Fact Sheet EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) available at http://wheat.okstate.edu/wheat-management/insectsdisease/EPP-7328.

 

Regarding leaf and stripe rust, I have seen mostly leaf rust over the last week, but signs of stripe rust (both active and inactive) also can be observed. On susceptible varieties that were not sprayed, leaf rust was severe (≥60% flag leaf area showing pustules). In his nurseries at Lahoma in north-central OK, Dr. Brett Carver (OSU Wheat Breeder) is seeing some active and inactive stripe rust. Given our cool and wet weather, stripe rust appears to be re-activating. Dr. Carver also is seeing abundant and severe leaf rust.

 

Related to the rusts and fungicides, I came across an interesting situation in central OK that I would like to share. A producer called this past week indicating he had a wheat field with severe leaf rust on lower leaves, but flag leaves were still green and rust free. So, he had the field sprayed with a triazole fungicide combination. About two weeks after spraying, he felt the flag leaves were showing rust and more flecking/chlorosis than should occur after a fungicide spray. A field visit confirmed what I had seen several years ago in my fungicide trial here at Stillwater in 2012, that is, fungicide was applied when flag leaves were infected with leaf rust but no pustules had yet been formed. Figure 1A shows a wheat leaf with leaf rust pustules on a susceptible variety that was not sprayed along with a single wheat leaf rust pustule magnified 63 times. Figure 1B shows a wheat leaf of a susceptible variety from my fungicide trial in 2012 that was sprayed two weeks before the photo was taken with a triazole fungicide. I remember when first seeing this, I thought it was rust pustules forming, but the rust pustules looked “funny.” With closer inspection I realized the “pustules” I was seeing were basically dead or dying and no viable spores were being formed (Figure 1B). Figure 1C is a photo from the producer’s field I visited on Thursday, which was sprayed with a combination of triazole fungicides approximately two weeks earlier. Note the similarities between the photos in Figures 1B and 1C. To me, this demonstrates two points. The first point is that this is an example of the “curative” action of triazole fungicides. The leaves in Figure 1B and 1C were infected with the leaf rust fungus and the fungus had grown through the flag leaf although no pustules had yet formed. Hence, the flag leaves were green and healthy appearing. Application of the fungicide killed the fungus over a period of time (i.e., “cured” the fungus). Even though “remnant” pustules formed, no viable spores formed in the pustules because the fungus was dead/dying. The second point (and perhaps most important point) is that this demonstrates the importance to apply a fungicide sooner rather than later. The applications made in Figure 1B and 1C helped maintain some green leaf tissue (more in 1B than in 1C), but if not applied when the fungicide was applied, these leaves would have been completely rusted and there would be no green flag leaf area left to contribute to grain fill. As it is, the wheat in Figures 1B and 1C will see some yield and test weight reduction, but not nearly as much as if fungicide had not been applied.

figure1a

figure1b

figure1c

Figure 1. (A) Leaf rust pustules on a wheat leaf of a susceptible wheat variety not sprayed with a fungicide and an individual leaf rust pustule (63X magnification); (B) Leaf rust pustules on a wheat leaf of a susceptible wheat variety 2 weeks after being sprayed with a triazole fungicide in 2012 in my fungicide trial and an individual leaf rust pustule (63X magnification); (C) Leaf rust pustules on a wheat leaf of a susceptible wheat variety about 2 weeks after being sprayed with a triazole fungicide in a commercial field in 2017. Note the reduction in green leaf, and the darkening of rust pustules in 1B and 1C; also note the difference in the magnified pustules where spores are visible in the not-sprayed pustule (as well as on the leaf), but spores are absent in the pustule on the leaf that was sprayed 2 weeks prior.