About Amanda De Oliveira Silva

I have served as an Assistant Professor and Small Grains Extension Specialist at Oklahoma State University since August 2019. I believe that close interaction with producers is vital to understand their production strategies and to establish realistic research goals. My program focuses on developing science-based information to improve the agronomic and economic viability of small grains production in Oklahoma and in the Southern Great Plains.

Grazing considerations: crown roots and first hollow stem

Posted on October 29, 2013 by Amanda De Oliveira Silva

There are a few cattle already on wheat pasture in Oklahoma and more that will be turned out in the coming weeks. An adequate crown root system is required to anchor wheat in place prior to grazing.

Wheat should not be grazed until enough crown roots are present to anchor the plant in the soil

Without these roots, wheat can be pulled from the soil during grazing, thinning final stands. Aboveground appearances can be deceiving, so it is important to pull plants from the soil to ensure the crown roots are there even if the plants appear large enough for grazing.

It is also important to make preparations for measuring first hollow stem prior to turning cattle out on wheat pasture. Grazing delays plant development; therefore, first hollow stem has to be checked in a nongrazed area. The nongrazed area does not have to be large and can be achieved through a panel exclosure or by simply moving one of the posts for an electric fence in a few feet. The key is to plan for the nongrazed area now so you can measure first hollow stem in February.

Get to know the OSU Wheat Variety Testing Program

Posted on October 8, 2013 by Amanda De Oliveira Silva

It occurred to me the other day that although I have publicized the forage, grain, and quality results from the OSU Wheat Variety Testing Program, I have never really given much effort to publicizing the day to day activities required to produce these results. So, over the next year I hope to write a few blogs to provide a little more insight into the workings of the system.

Location, location, location
Our program will have replicated trials at 23 sites in 2013/2014. These sites cover the state from Afton to Altus and McLoud to Keyes and some sites (e.g. Apache, Lahoma, Chickasha, Goodwell) have multiple trials. The location of trials are decided upon by throwing darts at a map (just kidding). We pick trial locations according to many factors including: visibility, uniformity, production history, local support, and cooperator involvement. Some locations (e.g. Lamont) have been in the system from the start, and others (e.g. McLoud) are fairly new additions. Given the miles between locations and a finite number of planting and harvest days, 23 locations is about the maximum we can handle and still complete operations in a timely fashion.

In addition to the small, replicated plots we organize and distribute ten-pound demonstration bags for County Educators. We typically have about 40 sets of 15 varieties for these ten pound “demo sets”.

OSU wheat variety testing locations cover Oklahoma from Afton to Altus and McLoud to Keyes. The Kingfisher location shown in this picture, also includes Dr. Carver’s elite nursery of advanced experimental lines

Who pays for all this?
The bulk of the expense of running the program comes in the form of salary, facilities, and miscellaneous overhead expenses and is largely covered by OSU through state appropriations (i.e. Oklahoma taxpayers). The bulk of the day to day operating expenses, such as seed, fuel, and mileage expenses, are covered through grants from the Oklahoma Wheat Commission and Oklahoma Wheat Research Foundation (i.e. Oklahoma wheat farmers). These two organizations also help with large equipment purchases such as tractors and combines. A relatively new area of support for the program is an entry fee system. The $500 per variety fee helps offset increasing expenses and is generally enough to assist with student labor for the project. We typically employ one or two graduate students and one or two undergraduate workers. Yes, we charge licensees for testing released OSU varieties but do not charge for OSU experimental lines.

Little packets of seed
Once we have determined which varieties will go at each location, we will send seed requests to participating companies. If everything goes well, we will receive seed in late August. We request one bag of most varieties and eight bags of varieties that will be included in the county demonstration packets.

Depending on the location, there are 25 to 45 varieties replicated four to eight times at each site. Each one of these plots starts with an envelope with either 60 (grain only) or 120 (dual purpose) grams of seed (120 grams is approximately 1/4 pound). This creates a total of about 4,000 envelopes that are weighed and packaged by hand each year. Envelopes are sorted according to a plot plan which randomly assigns varieties to locations within the field at each site. The plots plans are all created one at a time in Excel.

Planting five feet at a time
We have two planters. Our conventional planter sows eight six-inch rows and our no-till planter sows seven 7.5-inch rows. Seed is dropped into the distribution cone and released in the five foot alley between replications/blocks. A gear box is used to adjust the length of row over which the seed will be distributed. We work the ground with a small field cultivator at some locations and the producer or station manager works the ground for us at others.

Robert Calhoun and Matt Knori sow the 2013/2014 wheat variety test plots at Alva, OK. Robert is dropping a 60 gram envelope of seed into the cone that will evenly distribute the seed across eight six-inch rows over a distance of 25 ft.
The red boxes on the back are for 18-46-0 (DAP). We apply 50 lbs of DAP in furrow at all locations.
Photo courtesy Woods County Educator Greg Highfill

Planting by seeds per acre versus pounds per acre

Posted on September 13, 2013 by Amanda De Oliveira Silva

Should we plant by seeds per acre or pounds per acre? I will certainly not settle this issue in a single blog post, but I will provide ammunition for those in both camps in the discussion below. Before the discussion begins, I must come clean by acknowledging that when I came to Oklahoma ten years ago, I was solidly in the seeds per acre camp. As a crop consultant I spent most of October every year calibrating clients’ drills each time they changed varieties or field conditions changed. I was certainly not willing to entertain the notion that this could have been wasted time. After reading the published research on the subject, however, I have moved to the pounds per acre camp and will probably remain there unless seed prices increase dramatically OR seed quality improves significantly (I will elaborate below).

Why pounds per acre works
The published research on wheat seed size clearly shows that larger seeds produce more vigorous plants which result in more and larger tillers per plant. Additionally, the research indicates that if you sow the same number of seed of both small and large seeds from the same variety, the large seed will have an approximate 10% better yield potential. While not expressly mentioned in the research, it is reasonable to assume that small seed will produce less fall forage as well. For more reading on this subject consult Kansas Agricultural Experiment Station, Keeping Up With Research numbers 74 (1984) and 101 (1991).

We have established that larger seeds are better on a seed vs. seed basis; however, there are 36% more seeds in a bushel of wheat with 15,000 seeds per pound as compared to a bushel of wheat with 11,000 seeds per pound. So, when sowing by pounds per acre the additional seeds compensate for the smaller seed size and generally results in the same total number of tillers . This compensation effect means that planting by pounds per acre works for a wide range of seed sizes and varieties. This should not be taken as an excuse to plant poor quality seed, as the compensatory effect is not the same if you are sowing shriveled, light, or head-scab damaged seed.

When seeds per acre is a better option
If you are sowing high-quality, large seed, then seeds per acre might be a better option. To get this type of seed usually requires a favorable environment during grain fill, adequate fertility, and a foliar fungicide in-season followed by an aggressive seed cleaning process. I have heard Phil Needham say, and I agree, that 10% seed cleanout is a minimum. Most seed lots require 20 – 40% cleanout to achieve large-seed status. Including a gravity table in the cleaning process will increase seed quality further. The fact of the matter is that most of our wheat seed in the Great Plains simply does not consistently fall into this category. For this reason, if you are sowing “average” quality seed by seeds per acre, then adjust your seeding rate up accordingly to ensure you are not short on tillers.

Seeds per acre may also a better option if you are managing fertility to manipulate final tiller numbers. In this scenario, farmers will sow a set number of seeds per acre and adjust topdress rate and timing to encourage or discourage tillering to reach a desired number of heads at harvest. You can do the same thing when sowing by pounds per acre, but you will need an accurate stand count shortly after emergence. When used in combination with an accurate tiller count in February, a stand count will allow you to accurately estimate potential heads per acre and adjust accordingly.

Finally, if seed costs rise significantly in the future, a switch to seeds per acre might be justified. No one would suggest planting a $300 bag of corn or cotton seed based on pounds per acre. I don’t know what the wheat seed cost threshold is for switching to seeds per acre but would assume that if we ever reach this point seed quality will increase accordingly, making seeds per acre a better option.

Planting wheat in hot soils

Posted on September 6, 2013 by Amanda De Oliveira Silva

As is usually the case in Oklahoma, we currently have a wide range of soil moisture conditions. Soils in central Oklahoma are generally dry on top, but there is ample soil moisture below. Soils in western Oklahoma and the Panhandle are dry all the way down. A few drills have started rolling, but most producers are waiting on a “State Fair” rain to get started (for all you non-Okies, it usually rains sometime during the State Fair in early September). While moisture availability is the primary driver of wheat planting, it is not the only consideration for producers. Hot soil conditions can affect wheat germination too, and there are a few questions producers should ask themselves prior to planting into soil temperatures >90F.

If the wheat coleoptile does not break the soil surface, the germinating wheat plant will not survive.

Will you have to plant deep to reach moisture? That first structure protruding from a germinating wheat seed is actually not a leaf. It is the coleoptile. The wheat coleoptile is a rigid structure whose sole purpose is to “punch through” the soil surface so that the first true leaf emerges above the soil surface. If this does not happen, the first true leaf will try to extend below the soil surface, turn yellow, and take on an accordion-like appearance (picture above). Modern semi-dwarf wheat varieties have shorter coleoptiles than older, tall wheat varieties and coleoptile length is shortened even further by hot soil conditions. So it is important to plant a variety with a longer coleoptile length (e.g. Garrison or Doans) if planting deeply into hot soils. A rating of coleoptile lengths for wheat varieties can be found in OSU Fact Sheet 2141 OSU Wheat Variety Comparison Chart available at www.wheat.okstate.edu or at the direct link to the publication here.

Is the variety high temperature germination sensitive? High temperature germination sensitivity is a fancy way of saying that some wheat varieties simply don’t germinate well in hot soil conditions (e.g. 2174, Overley). The extent of the sensitivity varies by year, so Overley might germinate fine in 95F soils one year and produce a 10% stand in the same soil conditions the next. When sowing early, it is best to plant varieties that do not have high temperature germination sensitivity (e.g. Duster, Gallagher, or Armour). Soil conditions generally cool due to lower ambient temperatures or cooling rains by about September 20; however our summer temperatures seem to be arriving late this year, so it is best to know the level of germination sensitivity in the variety you are planting. A rating of high temperature germination sensitivity for wheat varieties can be found in the variety comparison chart linked above. A more detailed explanation of the phenomenon can be found in OSU Fact Sheet PSS 2256 Factors affecting wheat germination and stand establishment in hot soils (available by clicking here).

2013 Wheat variety performance test results posted

Posted on July 12, 2013 by Amanda De Oliveira Silva

All Oklahoma wheat variety test sites are now harvested and the results are posted at www.wheat.okstate.edu. I have posted a brief summary of the 2013 crop below. Over the next several weeks, I will be posting additional trial results on this blog along with opinion and analysis of results.

2013 WHEAT CROP OVERVIEW

At the time of writing this report, 2013 Oklahoma wheat production is estimated to be approximately 114 million bushels, which is roughly 26% less than 2012 production (Table 1). The production decrease was due to the combination of lower yields and fewer harvested acres. Given the challenges faced in the 2012-2013 wheat production year, however, most would consider the average yield and total production to be much better than expected.

Table 1. Oklahoma wheat production for 2012 and 2013 as estimated by OK NASS, June 2013
	2012	2013
Harvested Acres	4.3 million	3.8 million
Yield (bu/ac)	36	30
Total bushels	154.8 million	114 million

We have had several dry starts for wheat planting in Oklahoma, but the fall of 2012 might go down as the driest of the dry. A few timely rains in late August and early September allowed early and mid-September sown wheat to emerge and get a rapid start on forage production. This was the last substantial rain that most of western Oklahoma received until early 2013. As a result, much of our October-sown crop remained partially emerged in dry soil until after the first of the year.

Wheat that had emerged in September had consumed available water by early November and turned brown by December. Many fields were assumed dead, as there was no green tissue remaining above the soil surface (e.g. Marshall Dual-Purpose trial). This left little to no grazing potential for many dual-purpose wheat producers. Our Stillwater forage trial, for example, had less than 500 lb/ac (estimated) of available forage in early December, which is our normal forage measurement timing.

Rain was not plentiful in early 2013, but there was enough to allow the wheat crop to rebound. Wheat seed that had been lying in the soil germinated and early-emerging fields that had turned brown from drought were resuscitated and brought back to life. Wheat in southwestern OK and the Panhandle remained on life support throughout the season, surviving but never really thriving. Given these extreme circumstances, the grain yield at our Chattanooga, Altus, and Hooker sites are nothing short of amazing. Although wheat finally emerged at our Alva, Balko, Buffalo, Cherokee, Gage, Keyes, and Lamont sites, the stands were far too variable for use in comparing the yield potential of wheat varieties.

Drought was not the only weather-related issue Oklahoma wheat producers dealt with in 2013. There were multiple rounds of freeze events in late March and early April. Wheat in southwest Oklahoma and the Panhandle was affected by different freeze events but both sustained 30 to 80% tiller loss and were largely written off in the weeks following the freezes. Outside of far southwestern OK, cooler than normal conditions and some replenishment of soil moisture allowed regeneration of tillers. This, along with extended grainfill duration, allowed many wheat fields to recover and produce greater than expected grain yields (e.g. Apache variety trial). The cooler than normal spring temperatures were beneficial for wheat grainfill, but also delayed harvest by about one month as compared to 2012 and about two weeks as compared to the long term average.

It was a fairly quiet year regarding foliar disease. Pockets of the state suffered from heavy powdery mildew infestation in March and April, and some wheat producers chose to split-apply fungicides to combat this disease. There were also areas affected by glume blotch, tan spot, and septoria, but there was not much leaf or stripe rust present.

Yellow and purple leaves were tell tale signs that a late spring flush of aphids had transmitted barley yellow dwarf virus to several Oklahoma wheat fields. Armyworms were present late in the season, but generally did not reach threshold levels prior to maturity and few fields were sprayed. Winter grain mites took advantage of slow-growing, drought-stressed wheat and were a frequently reported problem in southwest OK, but the wheat curl mite takes top billing among mite pests in 2013. The wheat curl mite transmits wheat streak mosaic and high plains viruses. These two diseases are fairly common in the Panhandle but do not typically affect wheat in central OK. In 2013 fields as far east as Kingfisher tested positive for wheat streak mosaic and several central OK fields were affected. Growers affected by wheat streak mosaic should take care to ensure that any volunteer wheat or corn is dead at least two weeks prior to planting to reduce the risk of this disease in 2013-2014.

Wheat better than expected at Chattanooga, Kingfisher, and Chickasha

Posted on June 14, 2013 by Amanda De Oliveira Silva

Chattanooga, Kingfisher, and Chickasha wheat variety trial results are posted at www.wheat.okstate.edu. Grain yields at Chattanooga ranged from 12 to 36 bushels per acre. It is truly amazing that wheat somehow managed to produce these yields this in the presence of severe drought and three major freezes. Kingfisher wheat grain yields ranged from 32 to 47 bushels per acre and were more or less on par with expectations. This site had less than ideal moisture conditions, but adequate moisture to keep the wheat from turning brown as it did in many locations.

The Chickasha wheat variety trial had some problems. A late March freeze killed up to 58% of viable tillers in some varieties and lodging at harvest was moderate to severe. While leaf rust and stripe rust were not major factors, we did have a variety of leaf spotting diseases (e.g. tan spot, septoria, glum blotch) and severe, widespread bacterial blight/black chaff throughout the plot. In spite of these challenges, average yield at this site was 69 bushels per acre with yields ranging from 50 to 83 bushels per acre. While these yields are outstanding given the challenges of the year, they are not the best at the Chickasha research station. Approximately 200 feet from the variety trial was a growth regulator study planted to Iba that produced 98 to 102 bushels per acre. I have this same trial at two additional locations and will summarize results later in the year.

Both small plot combines running at Chickasha

Altus wheat variety trial results

Posted on June 7, 2013 by Amanda De Oliveira Silva

It was a rough year to farm wheat in Altus, OK. Our plots were sown into extremely dry soil on October 8, 2012 and received a total of 1.08 inches of rain by December 31. Total rainfall for the entire season was only 7.9 inches. Under these conditions it is amazing that wheat survived, but we somehow entered March with approximately 30 bu/ac yield potential. Some production fields in the area had 50 bu/ac potential and needed nothing more than a few rains to maintain this yield potential. The rains never came and Mother Nature dealt an additional card from the bottom of the deck with major freeze events in late March, late April, and early May.

Altus wheat variety trial results are posted at www.wheat.okstate.edu. Top varieties this year were Doublestop CL Plus (25 bu/ac), WB-Grainfield (22bu/ac), and the OSU experimental lines OK08328 (23 bu/ac) and OK09125 (22 bu/ac). Eleven out of 39 varieties made less than 10 bu/ac, and it is hard to say if drought or freeze had the larger effect on wheat yield. Based on the maturity rating of the top yielding varieties (ie late maturing) one could make the argument that freeze had the larger effect, but some relatively early and medium maturing varieties performed relatively well in the presence of the freeze (e.g. Duster and OK Bullet). The interactions are complicated and not easily explained.

Additional variety trial results will be posted as locations are harvested. To keep up with the latest results, follow me on Twitter @OSU_smallgrains

Wheat disease update 05 June 2013

Posted on June 7, 2013 by Amanda De Oliveira Silva

Wheat disease updates are written by Dr. Bob Hunger, OSU Extension Plant Pathologist

Oklahoma:

Not a lot to add since the last report and this is likely the last one from Oklahoma unless something out of the ordinary occurs. Wheat is being harvested in southwestern OK. I’ve heard reports that ranged from “about 180 bu from 50 some acres” up to around 30 bu/acre. Wheat around Stillwater is typically at medium dough with very little green leaf tissue left in the leaves. Stems are still mostly green but also beginning to fade. All of the wheat I looked at on Monday had 3 plump kernels/mesh.

A field day last Thursday (30-May) in Pawnee County (30 miles northwest of Stillwater) revealed a trial and surrounding field with severe leaf spot. Isolations from 3 varieties all yielded Pyrenophora (tan spot) and Septoria/Stagonospora with tan spo (Pyrenophora) more common than the other two. The wheat was approaching dough, so I don’t think there will be a huge yield hit – especially given the moisture and cool spell we have been having. I have only rarely seen tan spot and the leaf spot diseases in general this severe in Oklahoma.

Dr. Ned Tisserat (wheat Pathologist at Colorado State University) confirmed our suspected diagnosis of bacterial streak/black chaff in the variety trial at Chickasha (about 40 miles southwest of Oklahoma City). Symptoms were widespread and quite severe across all varieties, but similar symptoms due to leaf spots, drought, and freeze also contributed to the overall burnt appearance to the trial.

Finally, Bryan Vincent (crop consultant – north central OK) sent in photos of isolated spots in a wheat field in Kay County (just south of Kansas in north central OK). Although no sample was submitted, the photos and description of the situation definitely indicated this to be take all.

Reports/excerpts of reports from other states:

Kansas – Dr. Erick De Wolf (Professor/Small Grains Extension Pathologist, Kansas State Univ, Manhattan, KS) 03-Jun-2013: Fields in Central Kansas are maturing rapidly now and many fields were at the milk stages of development last week. The levels of stripe rust and leaf rust remain low in Kansas this year despite some earlier reports of stripe rust when the wheat was heading. It appears higher temps have slowed the development of stripe rust. Only trace levels of stripe rust can be found in most plots and commercial fields I visited May 27-31in Republic, Smith and Phillips counties (North central). Rust was absent from plots and fields I checked in Eills, Rush, Ness, and Lane counties (west central KS) this year and drought remains a serious issue for these growers.

I observed low to moderate levels of leaf rust in a variety testing location in Reno county (south central KS) on May 31. The incidence was near 80% but severity was still very low (generally less than 2%) of the flag leaves of susceptible varieties such as Overley, Jagger and Jagalene. The wheat in this plot was at the milk stages of kernel development so I do not expect any significant yield loss at this location.

Nebraska – Dr. Stephen Wegulo (Small Grains Extension Pathologist, Univ of Nebraska, Lincoln, NE) 30-May-2013: This afternoon I looked at breeding nursery plots in Lincoln (Lancaster County, southeast Nebraska). I found trace levels of stripe rust. The predominant disease was powdery mildew in the lower canopy, followed by leaf spots, mainly Septoria. There was a low incidence of Fusarium head blight (FHB) at low severity (one spikelet bleached on wheat, more on barley and in one case an entire barley head bleached). I suspect FHB is going to be a problem in the eastern part of the state. The timing of heavy, continuous rainfall coinciding with heading and flowering couldn’t be better for FHB development in the eastern part of the state. We have had these conditions over the last week or so and even before. Dr. P. Stephen Baenziger, UNL small grains breeder, happened to be at the nursery when I arrived. He told me his team saw stripe rust at higher than trace levels in a breeding nursery at Mead (about 30 miles north of Lincoln). Conditions are perfect for rapid development and/or spread of just any fungal or bacterial disease in eastern Nebraska. I also saw low levels of barley yellow dwarf virus in lines that appeared to be susceptible. A sample with virus symptoms I brought back from Saline County (also in southeast Nebraska) last week has tested positive for wheat streak mosaic.

Watch for armyworms in wheat

Posted on May 25, 2013 by Amanda De Oliveira Silva

We have a late-maturing wheat crop that has fought its way through freezes, howling winds and it is now receiving some needed rain. This cool weather is also helping slow the maturity of the wheat. Right now, wheat is vulnerable to infestation from armyworms. Armyworm infestations typically occur in late April through the first two weeks of May, but obviously, the cooler spring we have experienced this year has delayed their development.

Armyworm infestations occur more frequently around waterways, areas of lush growth, or areas with lodged plants. These areas should be checked first to determine the size of the infestation.

Early signs of an infestation include leaves with ragged margins that have been chewed. You may find “frass” i.e. the excrement from armyworm caterpillars, around the base of wheat stems. They also tend to clip heads from developing wheat plants. The head clipping I have noticed over the years us usually restricted to secondary tillers with very small, green heads that would not likely contribute much to yield.

Armyworm damaged wheat heads

Scout for armyworms, at 5 or more locations looking for “curled up worms”. Armyworm caterpillars tend to feed at night, so a good strategy is to bring a flashlight and look at fields after dusk when they are feeding up on the plant stems. The suggested treatment threshold for armyworms is 4-5 unparasitized caterpillars per linear foot of row.

Clipped heads from armyworm feeding

Armyworms have a number of natural enemies that help keep populations in check, if given a chance. In particular, parasitic wasps and flies attack them. If you find small white cocoons littered on the ground that are about ¾ the size of a cue tip, the natural enemies have already taken care of the problem.

Parasitized armyworms

I have noticed that there has been some fungicides being applied during the past few weeks. If an insecticide was added to that spray, it is likely to have reduced any armyworm population already established in the field. Still, it is important to check the field. Generally if wheat is past the soft dough stage, control is not warranted unless obvious head clipping can be seen, and caterpillars are still present and feeding. Worms feeding on the awns when plants are past soft dough will not cause enough yield loss to justify the expense of an insecticide application.

Consult CR-7194 Management of Insect and Mite Pests of Small Grains for information on insecticides registered for control of armyworms.

For more information on this topic, contact Tom A. Royer, Extension Entomologist at tom.royer@okstate.edu

Wheat disease update 25 May 2013

Posted on May 25, 2013 by Amanda De Oliveira Silva

Wheat disease updates are written by Dr. Bob Hunger, Extension Plant Pathologist

I and Nathalia Grachet (OSU Graduate Student) returned Friday from a trip and field days in the panhandle of Oklahoma. Wheat at Lahoma (25 miles west of Enid) ranged from full berry (watery) to the milk stage. Driving further to the northwest after about Alva was depressing as the condition of the wheat and the landscape in general deteriorated with what seemed like each passing mile. The field days we attended were at Balko (40 miles east of Guymon) and Hooker (20 miles northeast of Guymon). Wheat in these trials ranged from flowering to full berry (watery). Rick Kochenower (Panhandle Area Specialist – Agronomy) related the story that demonstrates the resilience of wheat. The Balko area was hit hard by the last freeze in April such that he felt there would be no wheat there. However, a mild May with just a little moisture allowed secondary tillers to come back, and if some rainfall and mild temperatures occurs for the next couple of weeks, some wheat will be harvested in the area. This is not the scenario over the entire panhandle. According to Rick, wheat in Cimarron County (far western county in the panhandle) is all but gone primarily due to drought whereas in Texas and Beaver County freeze and drought have both played a role in severely impacting wheat production.

Leaf and stripe rust were found this past week around Stillwater but not at a typical incidence or severity; leaf rust is especially lacking. Dr. Art Klatt reported being able to easily find leaf rust in his plots near Perkins, OK (15 miles south of Stillwater) in the range of 5-20S, which is lighter than typical. At Lahoma, Nathalia and I found both leaf and stripe rust but at low incidence and severity (especially leaf rust). Leaf spotting was more common, but it was difficult to determine if this was Septoria, Stagonospora, tan spot and/or physiological.

Signs of wheat streak mosaic and barley yellow dwarf can still be observed, especially around Lahoma where flag leaves are still mostly green. In the panhandle and northwestern OK it is difficult to discern virus damage from freeze and drought.

Reports/excerpts of reports from other states:

Nebraska – Dr. Stephen Wegulo (Small Grains Extension Pathologist, Univ of Nebraska, Lincoln, NE) 24-May-2013: Wheat in Nebraska is mostly in the boot to heading growth stages. There have been no new reports or observations of rust diseases since the observation of stripe rust at Mead on May 7. On May 21 and 22, I surveyed wheat fields in Lancaster, Saline, and Saunders Counties in southeast Nebraska. I did not find any rust diseases. The stripe rust that was observed at Mead on May 7 stopped activity following the high temperatures we had during the week of May 13 (including 100+ deg F on May 14), and never spread, similar to Carl Bradley’s observation in Champaign County, IL.

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