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.

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 virus, High 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.

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.

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.

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!

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.

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.”

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.

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.

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

The last three days of last week were spent in southwestern (Altus), central OK (Apache & Chickasha) as well as here around Stillwater. Wheat I saw at those locations ranged mostly from milk to soft dough, with some even approaching medium dough. I’m not sure about wheat in northern OK and over into the panhandle. The Panhandle is of particular interest with the far western parts of it receiving significant snow (up to 6-12 inches I heard on weather reports around Boise City).

Flag leaves on wheat across southwestern and in central OK are mostly gone as a result of rust (both stripe and leaf, but primarily leaf rust I think), wheat streak mosaic, and barley yellow dwarf. I saw little active stripe rust, but did see more active leaf rust. An abundance of leaves showed rust telia, but again, mostly leaf rust (I think). I also saw scattered white heads in wheat at Altus. Examination showed dark lower stem internodes and splitting of stems revealed cottony fungal growth in the lowest internode with a reddish/pinkish color indicating Fusarium root rot as the most likely cause (Figure 1). A sample of white plants with mostly sterile heads was brought to a field day at Apache, OK in central OK; examination revealed take-all as the likely cause (Figure 2). Barley yellow dwarf was present at all locations, but seemed more prominent at Chickasha.

Figure 1. (A) Scattered white heads often indicate root rots. (B) Lower stem internodes can be examined for discoloration and lesions that help to diagnose root rots and also split and examined for fungal growth. (C)  Low internodes also can be split and examined for fungal growth inside the stem. In this photo (C), the reddish/pinkish color indicates involvement of the fungus Fusarium that causes dryland root rot (photo credit: Dr. Bob Bowden; USDA-ARS; Manhattan, KS).

Figure 2.  Take-all of wheat as indicated by white heads/plants in the field (A) and dark growth on the lower stem (B).

As in my last update, Wheat streak mosaic virus (WSMV) continues to be found and reported across a large area of western Oklahoma. The cool wet weather will likely help manage infected plants to continue to mature, but yields definitely will be significantly impacted. 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. Stephen Wegulo, Professor/Extension Plant Pathologist, University of Nebraska, April 27, 2017:  “Late this afternoon, April 27, I found a significant amount of stripe rust in my wheat fungicide trial plots at UNL’s Havelock Research Farm in Lincoln, Lancaster County, in southeast Nebraska.  Incidence was moderate to high and severity on some leaves was greater than 50%, but mostly trace to 10%.  Leaves at all levels of the canopy from low to high have stripe rust.  Earlier in the afternoon, I did not find stripe rust at Mead, just 35 miles north of Lincoln; however, I suspect it is just a matter of time and it will be there.  Growth stage at Mead and Havelock ranges from Feekes 7 to Feekes 9.  Yesterday, April 26, Jenny Rees, UNL Extension Educator, found trace to low levels of stripe rust on wheat in Nuckolls County in south central Nebraska.  Therefore, to date stripe rust has been confirmed in the Panhandle, south central, and southeast regions of Nebraska.  Favorable (cool, wet) weather is forecast over the coming days.  Growers are encouraged to scout their fields and be prepared to apply a fungicide to protect the flag leaf.”

Dr. Erick DeWolf, Wheat Extension Pathologist, Kansas State University, May 1, 2017:  “The April 24 to May 1, 2017 period has been a critical week for the Kansas wheat crop. Multiple freeze events and snowfall in much of western region of the state dominate the concerns. What about the impact of the freezing temperatures on the development of disease? Unfortunately, the freezing temperatures are unlikely to kill the stripe rust and leaf rust that were already established in our fields. The frequent rains may stimulate additional disease development in areas of the state that escaped the freeze events.

A look at the weather during the past two weeks indicates that conditions were conducive for continued disease development in central and southeastern regions of the state. Many areas of central Kansas had between 12 to 44 hours of favorable temperature and humidity conditions. The southeast region experienced more than 50 hours of temperature and humidity that were favorable for stripe rust.

Observations from the field indicate that stripe rust has moved to the upper leaves of wheat in some parts of central Kansas. Stripe rust is now severe in some fields that were not protected with fungicides in southeast Kansas. The disease had moved to the upper leaves in this region of the state a few weeks ago. Stripe rust was also detected at low levels in the middle or low canopy in new parts of north central and northwest Kansas. Leaf rust was also reported in some additional counties this week with more activity farther west than we had seen to date. Leaf rust was still restricted to the lower and middle canopy in most fields but there are a few locations where the disease has moved to the upper leaves.

The reports of disease moving to the upper leaves in central Kansas and additional reports of disease further west are cause for concern. However, the concerns about freeze injury and damage done by recent snow complicate the decision to apply a fungicide to manage rust or other diseases. Growers in areas that escaped the freeze should be considering fungicide applications to prevent further development of stripe rust and leaf rust in susceptible varieties. Growers that are uncertain about yield potential because of damage from recent freeze events and snowfall should be more cautious. Growers with wheat that is at the flag leaf emergence or boot stage of development may have 10-14 days to make their final decision about fungicide applications for this year. Where possible, growers should wait to see how the crop recovers before investing in a fungicide application.”