Water-based drilling mud and wheat

Posted on February 20, 2014 by Amanda De Oliveira Silva

The recent increase in oil and gas exploration has resulted in the production of more water-base mud, (WBM), a by-product from the drilling process. The most common method of disposal for this material is land application to agricultural and grazing lands. As the name implies, water is the most common component of water base mud, but water-base mud also contains dissolved solids and sodium and a small amount on non-dissolved solids. Therefore the primary risk associated with over application of water-base mud is the soil becoming saline or sodic.

Water-base mud is mostly water, but also contains dissolved solids that, without agitation, will settle out of solution over time.

Soil salinity can be a problem for plants. Excessive salinity (approx. > 7,800 ppm for wheat) can decrease the ability of the plant to extract water from soil, even when water is plentiful. Salts can also interfere with germination. Germination reduction due to starter fertilizers with excess nitrogen or potassium, for example, are an example of how salts can inhibit germination. The solution for excess salt is typically water in the form of rainfall, as the water will move the salts deeper into the soil and out of the rooting zone. Unfortunately, rainfall in western Oklahoma is not always plentiful enough to achieve this downward movement and salts can accumulate.

OSU researchers Dr. Chad Penn and Dr. Jason Warren initiated a study at Lahoma, Oklahoma in 2012 to determine how in-season application of water-base drilling mud affected soil salinity and wheat yield. They evaluated 4,000 and 6,000 lbs/ac of total dissolved solids (6,000 lb/ac is the maximum allowed by the Oklahoma Corporation Commission) and five different timings from 16 October to 20 March. A detailed description of their findings is available in Current Report CR2272 at www.wheat.okstate.edu.

Water-base mud is spread in both liquid and solid form

Drs. Penn and Warren found that the salts from the water-base mud accumulated in the top three inches of soil initially. Rainfall for the next 90 days was scarce (0.5 inches total) and the salt remained largely in the top three inches of soil. Once rainfall picked up, however, the salts started moving downward through the soil profile. As expected the 6,000 lb/ac total dissolved solids rate resulted in greater soil salinity than the 4,000 lbs/ac rate, so the less you apply per acre, the lower the chances of increasing soil salinity to toxic levels.

In this study water-base mud applied to wheat prior to approximately first hollow stem did not significantly affect wheat grain yield; however, water-base mud applied March 20 (approximately jointing) reduced wheat grain yield. Their recommendation resulting from this study was not to apply water-base mud after February 15. It is also important to consider the effects of wheel traffic and associated soil compaction from applications of water-base mud.

Effect of water-base mud on subsequent wheat grain yield. Source: OSU Current Report 2272

This blog entry is a summarization of OSU Current Report 2272 Application of water-base drilling mud to winter wheat: impact of application timing on yield and soil properties. You can view the entire document at http://www.wheat.okstate.edu under Wheat Management then Fertility. Dr. Chad Penn (chad.penn@okstate.edu) and Dr. Jason Warren (jason.warren@okstate.edu) are authors of the publication.

First hollow stem advisor available on Mesonet

Posted on February 14, 2014 by Amanda De Oliveira Silva

First hollow stem occurs just prior to jointing and is the optimal time to remove cattle from wheat pasture. A new first hollow stem advisor tool available on the Oklahoma Mesonet provides Oklahoma wheat farmers a real time assessment of the current first hollow stem situation in the state and a forecast for the next two weeks. While the first hollow stem advisor is a valuable tool, it is not a substitute for scouting, as conditions in your field may vary from the estimates provided.

The advisor uses a mathematical model that predicts the probability of first hollow stem based on soil heat units and wheat first hollow stem category (early, middle, or late). The model was developed by J.D. Carlson at OSU using first hollow stem data from the wheat variety testing program, and model development was made possible through a grant from the Oklahoma Wheat Commission.

You can navigate to the first hollow stem advisor from www.mesonet.org by clicking on “Agriculture” then “Crop-Wheat” and looking for First Hollow Stem Advisor on the lefthand menubar. Or you can click here.

Screen Shot 2014-02-14 at 1.01.50 PM

Once you are at the first hollow stem advisor page, you will need to make a few selections. First, you have an option of viewing a statewide map or you can view data for a particular site in a table or graph. Next, you can select whether you want to view the current situation or a projection for the next one or two weeks. Finally, you will need to indicate if your variety falls into the early, middle, or late category. Click on the “look up by category” link if you are unsure where your variety falls.

hollowstem_early.current

Above is the statewide map for current conditions as of 14 February 2014. Other than a hot spot near Ardmore, there is less than 5% probability that we are at first hollow stem in Oklahoma. Note, however, that many locations are near the 576 heat unit threshold for 5% probability of first hollow stem. This is where the projection tools come in handy.

hollowstem_early.proj14day

The map above is the two-week first hollow stem projection through 28 February 2014 (i.e the map was created on 14 February 2014). These projections are based on historical weather data for the next two weeks, and do not take into account the current forecast which might be warmer or colder than the historical average. Note that almost the entire state up to I-40 is predicted be at or above the 25% probability level for first hollow stem by February 28. It is recommended that you start scouting once the advisor predicts a 5% probability of first hollow stem in your area. If you are going by the first hollow stem advisor alone (not recommended) cattle should be removed no later than when a 50% probability of first hollow stem has occurred.

First hollow stem nearing

Posted on February 14, 2014 by Amanda De Oliveira Silva

First hollow stem occurs just prior to jointing and is the optimal time to remove cattle from wheat pasture. Given the warm forecast for the next two weeks, it is likely that we will start seeing first hollow stem in Oklahoma wheat fields. Grazing past first hollow stem can reduce wheat grain yield by as much as 5% per day and the added cattle gains are not enough to offset the value of the reduced wheat yield.

Similar to previous years, we will monitor occurrence of first hollow stem in our wheat plots at Stillwater and report the findings on this blog. There is also a new first hollow stem advisor available on the Oklahoma Mesonet that can assist in determining when to start scouting.

Checking for first hollow stem is fairly easy.

You must check first hollow stem in a nongrazed area of the same variety and planting date. Variety can affect date of first hollow stem by as much as three weeks and planting date can affect it even more.
Dig or pull up a few plants and split the largest tiller longitudinally (lengthways) and measure the amount of hollow stem present below the developing grain head. You must dig plants because at this stage the developing grain head may still be below the soil surface.
If there is 1.5 cm of hollow stem present (see picture below), it is time to remove cattle. 1.5 cm is about the same as the diameter of a dime.
Detailed information on first hollow stem can be found at www.wheat.okstate.edu under ‘wheat management’ then ‘grazing’

Time to start topdressing wheat

Posted on January 8, 2014 by Amanda De Oliveira Silva

There are few crop inputs that deliver as much return on investment as nitrogen fertilizer. It takes approximately two pounds of nitrogen, costing approximately $1.00, to produce one bushel of grain worth about $6.00. Of course, nitrogen is not the only yield determining factor in a wheat crop. Also, the law of diminishing marginal returns eventually kicks in, but nitrogen fertilizer is still one of the safest bets in the house.

Top dress nitrogen fertilizer is especially important because it is applied and utilized at a time when the plant is transitioning from vegetative to reproductive growth. Several things, including the number of potential grain sites, are determined just prior to jointing and it is imperative that the plant has the fuel it needs to complete these tasks. Jointing also marks the beginning of rapid nitrogen uptake by the plant which is used to build new leaves, stem, and the developing grain head. The nitrogen stored in these plant parts will be used to fill the grain later in the season, and the plant is dependent on this stored nitrogen to complete grain fill.

In the bullet points below, I will hit the major points regarding top dress nitrogen for wheat. I have also posted three slide presentations with audio regarding topdressing wheat at my YouTube channel available by clicking here or by searching YouTube for OSU Small Grains.

When to apply

In order to have full benefit, nitrogen must be in the rooting zone by the time wheat is jointing. Jointing occurs around the end of February in southern OK and around the second week of March in northern OK.
Moisture is required to move nitrogen into the rooting zone. Since precipitation is usually very limited in January and February in Oklahoma we need the nitrogen out on the field when the precipitation arrives. This, along with the fact that we have 5.5 million acres to cover, means that we need to get started in January to get everything taken care of in a timely fashion.
If you are using the Sensor Based Nitrogen Recommendation system your yield predictions and nitrogen recommendations generally become more accurate as the season progresses; however, growers wishing to hedge their nitrogen bet could apply a partial top dress in January or early February and supplement with a second top dress just prior to jointing if SBNR recommendations call for additional nitrogen.
Do not apply nitrogen to frozen ground. Nitrogen will move with water. If melting snow or frozen rain is moving to the ditch, so will nitrogen applied to the soil surface.
Consider splitting or delaying top dress nitrogen applications to sandy soils until closer to jointing, as leaching can occur.

How much to apply

On average it takes about 2 lbs/ac of N for every bushel of wheat yield. In addition, dual-purpose wheat requires 30 lbs/ac of N for every 100 lbs/ac of beef removed. You can subtract your soil test NO3-N from these total requirements.
It is okay to adjust topdress N plans based on your current yield potential. When you submitted your soil test, you might have stated a 50 bu/ac yield goal which would require 100 lbs/ac of nitrogen; however, it is important to take a hard look and determine if this yield goal is still realistic based on your current crop status. I am not suggesting to adjust based on what you think the weather might do, but it is okay to take inventory and adjust your topdress N up or down based on current field conditions.
Don’t have an N-rich strip? It would be a lot cooler if you did. An N-rich strip would take the guess work out of adjusting your topdress N up or down based on your current crop conditions. Your county extension educator can provide more information on N-rich strips and you can find more information on the web at www.npk.okstate.edu

What source to use

The plant does not care about nitrogen source. A pound of nitrogen is a pound of nitrogen. Focus on getting the correct amount applied at the correct time, and choose your product based on price and application uniformity.
Use a source that can be applied uniformly. In my experience, spinner trucks or buggies are generally the least uniform. Air trucks or streamers are the most uniform.
Streamer nozzles almost eliminate leaf burn from UAN; however, leaf burn is generally not an issue until temperatures warm and/or you are applying fairly large amounts of UAN. Stream nozzles are also not affected much by wind and deliver a uniform pattern in a variety of conditions. There are also some studies that indicate banding of UAN through the use of stream nozzles will reduce nitrogen immobilization on crop residue. All in all, I am a big fan of streamer nozzles. You cannot, however, tank mix herbicides when using streamer nozzles.
Streamer nozzles provide uniform application of UAN in a wide variety of environmental conditions.

Poor nitrogen application can result in a streaked field. Some of the areas in this field were over fertilized while some were under fertilized resulting in wasted nitrogen and less than optimal crop yield.

Winter grain mites in SW OK

Posted on December 4, 2013 by Amanda De Oliveira Silva

Over the past week, I have received a few reports of winter grain mite activity in southwest Oklahoma. Winter grain mites are small (about 1 mm long) with black bodies and orange-red legs. Winter grain mites complete two generations per year and the adults can live for up to 40 days. The generation we are dealing with now resulted from oversummering eggs laid last spring. The second generation peaks in March/April and results from eggs laid in January/February.

Scouting
Winter grain mites are light sensitive and prefer calm air to windy conditions; therefore, scouting early in the morning, late in the evening, or on cloudy days generally works best. Be sure to look under residue in no-till fields and under clumps of soil in conventional-till fields.

Winter grain mites on wheat near Blair, Oklahoma.

Injury
Winter grain mites feed by piercing plant cells in the leaf, which results in “stippling”. As injury continues, the leaves take on a characteristic grayish or silverish cast. Winter grain mites are more likely to cause injury in wheat if it is already stressed due to lack of moisture or nutrients. Also be advised that freeze injury can easily be confused for winter grain mite injury.

When to spray
There are no established thresholds for winter grain mite. Healthy, well-fertilized wheat plants can generally outgrow injury, so it takes large numbers to justify control. If there is injury present AND large numbers of mites (~10 per plant) present in grain only wheat this time of year, you might consider control. If the wheat is to be grazed, I would simply monitor the situation in most cases and only spray if injury became severe.

What to spray
There are not a lot of pesticides with winter grain mite listed on the label, and most products have grazing restrictions. Malathion and methyl parathion have been shown to provide effective control in the past. Consult OSU Current Report 7194 Management of insect and mite pests in small grains for a more complete listing of available pesticides.

Hessian fly strikes back!

Posted on December 4, 2013 by Amanda De Oliveira Silva

Back in 2006 it appeared that Hessian fly was going to be the demise of no-till wheat production in Oklahoma. Early planting, lack of crop rotation, and no-till monocrop wheat all create a favorable environment for Hessian fly, and there were several early-sown fields that were completely lost to the Hessian fly in 2006 & 2007. About that same time OSU release a variety named Duster that was an excellent grazing wheat with good yield potential. Duster also happened to be Hessian fly resistant. (If you are not a Star Wars fan, skip the next sentence) This resistance was a clear proton torpedo in the thermal exhaust port of the fully operational Hessian fly Death Star.

Mature Hessian fly larvae are brown in color and often referred to as flaxseed. Tillers with larvae will not recover and will eventually die and slough off.

Over the past four years, I have received very few calls about Hessian fly. It seemed as thought the adoption of Duster and unfavorable environmental conditions resulted in a dramatic reduction in Hessian fly in Oklahoma, but there are some indications Hessian fly is making a return. I have received a few calls about Hessian fly this fall, most of them from southwest Oklahoma. In most cases producers had either switched to a newer variety that was not Hessian fly resistant or changed to a nonresistant variety because they were displeased with Duster’s performance the past two years.

There are no curative treatments for Hessian fly in wheat. If you currently have a field that is infested with Hessian fly, the first step is to assess the level of infestation. If a plant with four viable tillers has one infected, then the impact on yield might not be that great, as we could have additional tillering in late winter. A field with the majority of tillers infected is likely a good candidate for graze out.

It is never too soon to be thinking of how to limit the impact of Hessian fly on next year’s crop. Planting a resistant variety still remains the most effective technique of combating the Hessian fly menace in Oklahoma for dual-purpose wheat farmers. To determine which varieties are resistant, consult a current OSU Wheat Variety Comparison Chart. Insecticide seed treatments are effective early in the season, but do not typically last long enough to provide season long control in Oklahoma. Cultural practices such as crop rotation and delaying planting until mid October will also help reduce Hessian fly infestations but might not be suitable for all operations.

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.

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