Kickoff of the college football season and the start of wheat planting are Labor Day traditions in the southern Great Plains. Many producers are waiting to see if rain forecasted for this weekend materializes, but it is likely that forage-based wheat farmers will start sowing wheat next week whether it rains or not. This means sowing wheat into hot soil conditions which can cause wheat germination and emergence issues. Given the potential problems, there are a few questions producers should ask themselves prior to planting into soil temperatures >90F.
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).
Agriculture Policy News is written by Dr. Jody Campiche, OSU Extension Economist. You can find more of her newsletters at http://agecon.okstate.edu/agpolicy/index.asp?type=newsletters
The new Supplemental Coverage Option (SCO), available through the federal crop insurance program, will be available for corn, cotton, grain sorghum, rice, soybeans, spring barley, spring wheat, and winter wheat in selected counties for the 2015 crop year. The first enrollment deadline is September 30, 2014 for winter wheat. Producers will have the option to purchase SCO through a crop insurance agent along with their underlying individual insurance policy.
SCO is designed to cover county-wide losses and complement a producers’ individual insurance policy which is a new concept as producers have not previously been allowed to stack insurance policies for the same crop. To be eligible to purchase SCO, producers must also have an individual policy for the crop enrolled in SCO. The individual policy can be a Revenue Protection (RP) policy, a Revenue Protection with Harvest Price Exclusion (RP-HPE) policy, or a Yield Protection (YP) policy. SCO coverage is tied to the individual yield or revenue insurance policy. So a producer with an individual Yield Protection (YP) policy would only have the option to purchase an SCO yield protection policy (as opposed to a revenue protection policy). SCO will cover losses from 86% minus the coverage level of the producer’s individual policy. For example, if a producer has a 70% RP policy, the SCO coverage level would be 16% (86% – 70%). As shown in the figure below, SCO is only offered in certain counties/states for 2015 winter wheat and spring wheat crops.
For Oklahoma, the list of counties with 2015 winter wheat coverage and the SCO expected county yields are shown in the table below.
|SCO Expected County Yield|
Enrollment in the new Price Loss Coverage (PLC) and Agriculture Risk Coverage (ARC) programs through the Farm Service Agency (FSA) are now tied to enrollment in the SCO crop insurance program. The USDA Risk Management Agency (RMA) just released rules/guidelines for the SCO program but the Farm Service Agency (FSA) has not released rules/guidelines for ARC and PLC. Therefore, the information provided in this blog post is based on my current (08/11/2014) understanding of the interaction between these programs and could change once all final program details are released.
Producers who elect to participate in ARC are not eligible for SCO for the crop/farm number participating in ARC. Enrollment in ARC or PLC occurs on an FSA crop/farm number basis. Producers cannot receive benefits for both ARC and SCO on the same acreage/farm number of a crop. SCO is elected on crop/county basis so producers will need to report which acreage/farm numbers are enrolled in SCO and which acreage/farm numbers are enrolled in ARC.
The ARC/PLC decision is a one-time decision that will remain in effect for the life of the farm bill. Producers will likely enroll in ARC/PLC in late 2014 or early 2015. The initial ARC/PLC enrollment is for the 2014 crop year (although it may not take place until 2015). SCO is not available for the 2014 crop year. SCO is available for certain crops/counties for the 2015-2018 crop years. The SCO election will take place each crop year when a producer enrolls in an individual RP, RP-HPE, or YP policy. A producer who enrolls a crop/farm number in ARC will not have the option to purchase SCO for that crop/farm number for any of the 2015-2018 crop years. The deadline to enroll in SCO for winter wheat for the 2015 crop year is September 30, 2014.
For ARC and PLC, producers enroll base acres (with the exception of generic or cotton base acreage) but producers enroll planted acres in SCO. So, a producer could enroll base acreage of one crop in ARC on a particular farm number but plant a different crop on the same farm number and enroll that crop in SCO.
For example, assume Producer Jones has 100 base acres of grain sorghum on FSA farm number 1111 and 100 base acres of wheat on FSA farm number 2222:
Scenario 1: Producer Jones plants 100 acres of wheat on farm 1111 and 100 acres of wheat on farm 2222 during the 2015 crop year. Here are some available options:
- Farm 1111
- Enroll the grain sorghum base acreage in PLC, option to purchase SCO on planted wheat acres for the 2015 crop year (and through 2018)
- Enroll the grain sorghum base acreage in ARC, option to purchase SCO on planted wheat acres for the 2015 crop year (and through 2018)
- Farm 2222
- Enroll the wheat base acreage in PLC, option to purchase SCO on planted wheat acres for the 2015 crop year (and through 2018)
- Enroll the wheat base acreage in ARC, CANNOT purchase SCO on planted wheat acres in any year
Scenario 2: Producer Jones plants 100 acres of grain sorghum on farm 1111, 50 acres of wheat on farm 2222, and 50 acres of canola on farm 2222. Here are some available options:
- Farm 1111
- Enroll the grain sorghum base acreage in PLC, option to purchase SCO on planted grain sorghum acres for the 2015 crop year (and through 2018)
- Enroll the grain sorghum base acreage in ARC, CANNOT purchase SCO on planted grain sorghum acres for the 2015 crop year (and through 2018)
- Farm 2222
- Enroll the wheat base acreage in PLC, option to purchase SCO on planted wheat acres, CANNOT purchase SCO on the planted canola acres for the 2015 crop year since SCO is not available for canola in 2015 (may have the option to purchase SCO for canola in some counties in 2016-2018, but this is uncertain)
- Enroll the wheat base acreage in ARC, CANNOT purchase SCO on the planted wheat acres in any year, CANNOT purchase SCO on the planted canola acres for the 2015 crop year since SCO is not available for canola in 2015 (may have the option to purchase SCO for canola in certain counties in 2016-2018)
Since producers will likely not be able to enroll in ARC or PLC prior to the Sept. 30 deadline for SCO coverage on 2015 winter wheat, SCO coverage can be withdrawn on any farm where producers intend to elect ARC for winter wheat by the earlier of their acreage reporting date or Dec. 15, without penalty. This allows producers additional time to make an informed decision between ARC or PLC for winter wheat. If producers withdraw SCO coverage for a farm by the earlier of their acreage reporting date or Dec. 15, they will not be charged a crop insurance premium. In order to withdraw coverage without penalty, producers must notify their crop insurance agent of their intended election for ARC by the earlier of their winter wheat acreage reporting date or Dec. 15. The option to withdraw SCO coverage will only be allowed for the 2015 crop year for fall planted wheat.
A producer who chooses to purchase an SCO policy has several options. The producer could keep the previous coverage level on the individual RP, RP-HPE, or YP policy and add SCO coverage. As an example, if a producer has a 70% RP policy, the producer could buy 16% SCO coverage (86%-70%). The producer could also decide to lower the coverage level on the individual policy and add more SCO coverage. For example, the producer could lower RP coverage to 60% and buy 26% SCO coverage (86%-60%). However, it is important to note that if a producer decides to withdraw from SCO later this year (due to enrollment in ARC), the producer would not be able to change the coverage level of the underlying policy for the 2015 crop year. For example, assume a producer usually purchases a 70% RP policy on wheat. If the producer decides to lower RP coverage to 60% and purchase 26% SCO coverage (86%-60%) for the 2015 crop year, but then decides to withdraw from SCO, the producer would not be able to change the 60% RP coverage for the 2015 crop year.
Due to the complexity of decisions related to ARC, PLC, SCO, and individual insurance policies, producers should consider several factors. Some of the key points to think about are:
- What level of coverage does the producer currently have on the individual policy?
- SCO only provides coverage up to 86% so a producer with an 85% RP policy may not want SCO coverage (although the producer could lower the coverage on the individual policy and buy more SCO coverage
- Is SCO offered for the crop/county in 2015 and/or later years?
- RMA may add additional crops/counties for the 2016 crop year.
- Does the producer currently have enterprise units on the underlying individual crop insurance policy? If so, the producer may want to examine the marginal costs of increased coverage on the underlying policy as opposed to adding SCO coverage.
- Enterprise units would cover losses closer to the individual farm-level than county-level SCO coverage (may cost less than SCO depending on coverage level).
- SCO covers losses at the county-level while an RP, RP-HPE, or YP policy covers losses at the farm level. If a farm-level loss occurs but a county-level loss does not occur, SCO would not pay an indemnity. If a farm-level loss does not occur but a county-level loss does occur, SCO would pay an indemnity.
- What is the cost of the underlying individual crop insurance policy?
- Can the producer obtain higher levels of coverage on the individual policy at affordable rates? If not, SCO could provide a higher level of coverage at a more affordable rate. The SCO premium subsidy is 65% compared to a 59% subsidy for a 70% RP policy (the subsidy varies for other levels of coverage on an individual policy).
- Does the producer want to enroll in ARC for a particular crop/farm number? If so, SCO is not an option for the same crop/farm number.
- Does the producer want to have the option to purchase SCO for a crop/farm number in a later year (after the 2015 crop year)? If so, the crop/farm number cannot be enrolled in ARC.
- Does the producer want to have more time to think about SCO for the 2015 winter wheat crop? If so, the producer may want to obtain SCO coverage for winter wheat prior to the Sept. 30 deadline and withdraw later if enrolling in ARC.
For additional information:
SCO Endorsement: http://www.rma.usda.gov/policies/2015/15sco.pdf
SCO Underwriting Standards Handbook: http://www.rma.usda.gov/handbooks/18000/2015/15_18180.pdf
At the time of writing this post, 2014 Oklahoma wheat production is estimated to be approximately 51 million bushels, which is roughly half of 2013 production (Table 1). Oklahoma has not seen wheat production this low since the 43 million bushel crop of 1957, and with any luck, production will not be this low again for at least another 60 years.
|Table 1. Oklahoma wheat production for 2013 and 2014 as estimated by OK NASS, July 2014|
|Harvested Acres||3.4 million||3.0 million|
|Total bushels||105 million||51 million|
The 2013-2014 wheat production season had a good start in central Oklahoma. Topsoil moisture was short in September, but October rains resulted in favorable conditions for wheat emergence and establishment. In addition, many areas had a fair amount of stored soil moisture from the summer of 2013. This stored soil moisture allowed sites such as Chickasha and Lahoma to produce 43 and 47 bu/ac average wheat yield on less than eight inches of rainfall during the growing season. Stored soil moisture also contributed to adequate forage production at grazed sites such as Marshall Dual-Purpose, but production of a forage crop did not leave behind enough moisture to fuel much of a grain crop.
The multi-year drought never released its stranglehold on western Oklahoma during the 2013-2014 wheat production season. Small rains here or there allowed most producers to obtain an acceptable stand of wheat, but moisture was never sufficient to spur tillering or leaf area development. Early winter snowfall made for a few bright spots for forage production in southwestern Oklahoma, but this moisture was quickly utilized by growing wheat plants and dry conditions soon returned. As a result, many fields in southwestern and western Oklahoma were abandoned and not taken to harvest.
The winter of 2013-2014 wasn’t just dry; it was cold too. Young, drought-stressed wheat plants had difficulty dealing with the cold, windy conditions, and winterkill was common in late-sown wheat. Winterkill was also common in grazed wheat that was stressed by heavy grazing pressure and inadequate soil moisture. Considerable winterkill was also present in no-till wheat without adequate seed to soil contact in northwestern Oklahoma. The inadequate seed to soil contact was generally the result of heavy residue from the previous year’s wheat crop.
While the wheat crop did not appear to be on its way to bumper production, most producers hoped for a turnaround similar to 2013 and topdressed in late winter. Unlike the spring of 2013, however, the rains never came and much of this topdress N applied did not make it into the soil until the crop was at boot stage or later.
The cold winter delayed the onset of first hollow stem by about five days as compared to 2013 and 25 days as compared to 2012. Despite a slow start to the spring, wheat in southern Oklahoma was near heading when a hard freeze occurred the morning of April 15, 2014. As expected, drought stressed wheat in advanced stages in southwestern Oklahoma suffered severe freeze damage; however, injury from the 2014 spring freeze did not always follow the “rule of thumb” guidelines used by agronomists. Many areas that received small amounts of rain just prior to the freeze seemed to escape widespread injury, regardless of growth stage. In southcentral Oklahoma, injury seemed to be most severe on later maturing varieties that were approximately Feekes GS 7 to booting, while earlier-maturing varieties that were just starting to head escaped freeze injury. Wheat that was barely past two nodes in northern Oklahoma suffered severe injury, while more advanced wheat in central Oklahoma endured similar temperatures with minimal injury.
There were relatively few insect or disease issues to deal with during the 2013-2014 wheat production season. Winter grain mite and/or brown wheat mite infestations proved to be too much for some drought stressed wheat fields in northcentral and northwestern Oklahoma. Some fields already devastated by the drought were left unsprayed, while others still showing some sign of yield potential were treated.
Other than a rare siting of a single leaf rust pustule, there was no foliar disease in Oklahoma in 2014. The lack of foliar disease is evidenced by the lack of response to foliar fungicides at either Chickasha or Lahoma. These two sites provided a rare opportunity in 2014 to observe yield impacts of foliar fungicides in the absence of disease, as most years we report at least light or negligible foliar disease at these sites. While foliar disease was not an issue in 2014, wheat streak mosaic virus was an issue for many producers. This disease has historically been most prevalent in northwestern Oklahoma and the Panhandle. Wheat streak mosaic virus was confirmed in several fields downstate this year, however, and it is likely that some fields affected by wheat streak mosaic virus were not identified as such because it is sometimes difficult to distinguish wheat streak mosaic virus symptoms from those of severe drought stress. The wheat variety testing program was not immune from this disease, and we lost our Kildare location to wheat streak mosaic virus.
Warmer temperatures in May hastened crop maturity and the Oklahoma wheat harvest began near Frederick on May 22, 2014. By the first week of June, harvest was in full swing, only to be delayed by rain shortly thereafter. Harvest resumed across most of the state by June 13 and was mostly completed by June 30. The exceptions being some waterlogged areas in northern Oklahoma. The Cherokee Mesonet site, for example, reported 5.1 inches of rainfall from October 1, 2013 to May 31, 2014, but the same site received 10 inches of rain from June 1 to June 30, 2014.
The 2014 Oklahoma wheat harvest is underway and results from the Walters and Thomas wheat variety trials are now posted at http://www.wheat.okstate.edu. Depending on field operations, I usually get variety trial results posted on the web within a day or two of harvest. The best way to learn when results are posted are to follow me on Twitter @OSU_smallgrains or subscribe to our Extension news list serve (send me an email at firstname.lastname@example.org to be added to the listserv).
I have posted a few pics from our harvest operations below.
Originally posted on Down and Dirty with NPK:
In the mid-1970s Dr. Robert Westerman banded 18-46-0 with wheat at planting in a low-pH soil near Haskel Ok. The impact was immediately evident. Soon after Oklahoma State University recommended the “Banding of Phosphate in Wheat: A Temporary Alternative to Liming” Figure 1. This method was a Band-Aid solution for the significant amount Oklahoma winter wheat production area which was either too far from a reliable lime source or under a short term lease contract.
Still today grain producers throughout the United States commonly farm a large percentage of land that is not their own. In the leasing process agreements can widely vary both on length of the lease and the amount of inputs that the land owner will pay. The wheat belt of Oklahoma is known for having large areas with low soil pH levels…
View original 1,199 more words
The introduction of two-gene Clearfield technology and the release of an Oklahoma-developed two-gene Clearfield wheat variety have resulted in increased interest in the Clearfield system in the southern Great Plains. This has also resulted in several questions, some of which I will attempt to answer in this blog post. If you have specific questions regarding rates, timings, etc., I encourage you to contact your local BASF representative.
Are Clearfield wheat varieties GMO’s? No. The Clearfield system is a non-genetically modified crop herbicide tolerance technology.
What is two-gene technology and what does it mean? As the name implies, two gene Clearfield varieties have two copies of the gene that confers resistance to imidazolinone herbicides. Two gene varieties have “Plus” or “+” in the name (e.g. Doublestop CL Plus). In wheat two-gene technology provides the option of adding 1% v/v methylated seed oil (MSO) to the spray solution. In my experience, addition of 1% v/v MSO greatly increases Beyond efficacy on feral rye. Methylated seed oil should NOT be added to the spray solution for one-gene Clearfield varieties, as crop injury will occur.
What is the new OSU two-gene Clearfield variety? Doublestop CL Plus was released by OSU in 2013 and is marketed through Oklahoma Genetics Inc. It is a late to first hollow stem and late maturity (about the same as Endurance) variety with a wide area of adaptation. A few of the strengths of Doublestop CL Plus include yield potential, acid soil tolerance, test weight, and milling and baking characteristics. More information on Doublestop CL Plus can be found by clicking here.
Can I save seed from Clearfield varieties? No. The gene that confers the Clearfield trait is protected by a utility patent and new seed (registered or certified) must be purchased each year.
Can I grow a Clearfield variety two years in a row? The better question might be should you grow a Clearfield variety two years in a row? Multiple years of using the same herbicide or herbicide mode of action can result in herbicide resistance. Of particular concern is jointed goatgrass, which has the ability to hybridize with wheat. This ability to hybridize could result in a population of resistant jointed goatgrass in a fairly short time period. So, if jointed goatgrass is the primary weed problem, rotating crops and/or herbicide chemistries to avoid consecutive years of Clearfield technology is a good stewardship practice.
Other grasses, such as feral rye, do not have the potential to hybridize, but the potential for weed resistance is still there through selection pressure. In these situations, I would not be as concerned about two consecutive years of a Clearfield system, but would certainly switch herbicide chemistry for a year after that.
Ultimately, it is important to rotate crops and herbicide modes of action to ensure the longevity of the Clearfield system. Weed resistance is bad and it is worse if your farm is the epicenter of the problem. Clearfield stewardship guidelines are available from BASF by clicking here
This blog post is an abbreviated posting of our wheat forage results. For the complete report, consult OSU Current Report 2141 Fall forage production and date of first hollow stem in winter wheat varieties during the 2013-2014 crop year by clicking here.
As was the case across most of Oklahoma, our wheat plots were sown into dry topsoil in late September. Soils in southwest and northwest Oklahoma were extremely dry due to multiple years of drought, and wheat pasture was short in these areas of the state. Summer rainfall provided ample subsoil moisture in the central part of the state, but topsoil was largely dry through September. Rains fell across much of the state in October and provided the fuel needed to build wheat pasture. Unfortunately, these October rains would be the only significant rainfall events most of the Oklahoma wheat crop would receive .
Fall forage production by winter wheat at Stillwater and Chickasha averaged 3,240 and 2,580 pounds per acre, respectively (Tables below). There was a large group of varieties at Stillwater and Chickasha that produced statistically equivalent forage yield, and producers are encouraged to consider two and three year averages when available.
|Table 2. Fall forage production by winter wheat varieties at Stillwater, OK during the 2013-2014 production year.|
|—————lbs dry forage/acre—————-|
|OGI||Doublestop CL Plus||3,200||3,020||-|
|CWRF||Brawl CL Plus||2,980||2,860||-|
|Table 3. Fall forage production by winter wheat varieties at Chickasha, OK during the 2013-2014 production year.|
|–lbs dry forage/acre–|
|CWRF||Brawl CL Plus||2,830||-|
|OGI||Doublestop CL Plus||2,700||-|
First hollow stem data are reported in ‘day of year’ (day) format (table below). To provide reference, keep in mind that March 1 is day 60. Average occurrence of first hollow stem at Stillwater in 2014 was day 77. This was approximately five days later than 2013 and 25 days later than in 2012 and was the result of much cooler than normal temperatures. Unlike previous years, there was only about ten days difference among varieties in occurrence of first hollow stem.
|Table 4. Occurrence of first hollow stem (day of year) for winter wheat varieties sown in 2013 and measured in 2014 at Stillwater, OK|
|–day of year–|
|OGI||Doublestop CL Plus||80|
|CWRF||Brawl CL Plus||83|
Wheat disease updates are written by Dr. Bob Hunger, OSU Extension Plant Pathologist
Oklahoma: Wheat around Stillwater is mostly at GS 10.5.1 (start of flowering) and is looking dry. With temps forecast in the upper 90s for the next 3-4 days and no rain, conditions will continue to deteriorate. Areas in other parts of the state are worse, with only a few areas better.
This past week I traveled from to southwestern OK stopping at numerous fields along the way as well as the variety trials or demonstrations at Kingfisher (60 miles southwest of Stillwater), Granite (southwestern corner of OK) and El Reno (20 miles west of OKC). Typically wheat was at my knee height or shorter and thin. I saw no foliar diseases, but did find several locations where I believe wheat streak mosaic and/or high plains disease was present. Samples are being evaluated to confirm, but samples processed by the Diagnostic Lab this past week from the panhandle and from central OK would support this (i.e., positive for Wheat streak mosaic virus and/or High plains virus). I also have noted symptoms of barley yellow dwarf in my trials around Stillwater, but no stunting is associated with these symptoms most likely indicating a spring infection. I did have a report from Roger Musick in central Oklahoma that he found a high incidence of tan spot and light leaf rust in a no-till wheat field under pivot irrigation. That is the only confirmed report of foliar disease I have received.
Reports/excerpts of reports from other states:
Mississippi Dr. Tom Allen (Extn Plant Pathologist, Mississippi State University) 03-May-2014: Wheat throughout MS ranges from flowering north of Highway 82 to wheat that has likely reached ripening stages south of I-20 (I haven’t seen as much of that wheat in more than 2 weeks).
Trace levels of wheat rust were observed in the Greenwood, MS area on Tuesday by a chemical distributor field rep. I confirmed the observation by text photo. In addition, I was able to find a few stripe rust infected leaves on the experiment station in Stoneville last Friday. I haven’t made much about the stripe rust confirmation because the plants were volunteer plants under a rainout shelter. I was shocked to see that most of the infected leaves had already formed telia as a result of the warmer temperatures. At present, we have not confirmed stripe rust in either a commercial field, variety trial plot, or any other part of the state.
Quite frankly, this is one of the cleanest wheat crops I’ve observed. Until the past week the only observable diseases were bacterial leaf streak throughout much of the state and Barley yellow dwarf virus. I rated the variety trial south and west of Hattiesburg a few weeks ago and also observed a low level of scab at that location. Some Septoria leaf blotch has been observed, tan spot in a few fields in eastern MS, and some glume blotch. In addition, since we were so wet and cold throughout much of the winter, and the rain continued, field work has been way behind so we’re starting to get some calls regarding glyphosate drift as well as paraquat.
Arkansas (Dr. Jason Kelley (Assoc Prof; Wheat & Feed Grains; Univ of Arkansas) 02-May-2014:
This week I visited several wheat fields around the state and looked through the plots that I have at the Lon Mann Research Station at Marianna. Overall I would say the crop is later than it was last year, which seemed very late. Many fields in central Arkansas heading this week, fields in south Arkansas generally headed last week and by this time next week most fields in Northeast Arkansas will likely be fully headed. According to the Arkansas Agricultural Statistics Service report, for the week prior to April 28th only 17% of the crop had headed. This compares to 67% for the five year average and 32% last year.
Overall the crop looks okay, but I can tell the last few weeks of rain has taken a toll on it with yellow pockets of wheat from mud holes is more common than it should be. Foliar disease levels have been low with the exception of Septoria leaf blotch, which is common in most fields lower in the canopy, but has moved up the plant in the last week on more susceptible varieties. I found a small hot spot of stripe rust on Wednesday April 30th at my plots at Marianna. This was the first reported stripe rust in the state. At this point with most wheat headed, heading or will be headed by the end of next week, stripe rust will most likely not have enough time to get well established and be a big issue this year.
I have been out in much of the state with wheat field days this week and wanted to share a few observations. Drought conditions are worsening in most wheat producing areas of the state and yield potential is declining fairly rapidly. An area roughly extending from Chickasha to Enid along highway 81 still has some potential, provided that that we receive rain soon. The same can be said for a few small pockets of wheat that received rain earlier this spring in Alfalfa, Grant, and Kay counties. With temperatures predicted to climb to the upper 90’s next week, however, the potential in these areas could decline rapidly. Most other areas of western Oklahoma have very limited or no yield potential remaining.
The effects of the April 15th freeze are still showing up in the Oklahoma wheat crop. We have several fields with lots of tillers but few heads. Most wheat south of Hwy 51 in Oklahoma is as fully headed as it is going to get. That is, the heads that were not killed by the freeze are fully emerged. Tillers that still look yellow or even green but are not headed out most likely have dead wheat heads inside. These can easily be identified by splitting the stem and examining the wheat head as shown in the pictures below.
Wheat disease updates are written by Dr. Bob Hunger, OSU Extension Plant Pathologist
Oklahoma: Wheat around Stillwater is mostly at GS 10.2 to 10.4 (heads ¼ to ½ emerged from boot). Conditions are still dry, not only around Stillwater, but also around much (if not all) of the state. Some rain fell this past week in the 1 inch range in a few areas, but in southwestern OK it was most likely too late to help the wheat. Freeze damage also is becoming much more apparent.
Dr. Jeff Edwards (OkSU Small Grains Exten Spec) and I looked at wheat and attended a field day yesterday evening near Apache, OK (about 75 miles southwest of Oklahoma City). The variety trial and field at Apache was lost because of freeze. Wheat at Dr. Edward’s trial at Chickasha (30 miles northeast of Apache) also had some freeze damage but not as severe as the wheat around Apache. No foliar diseases were seen at any field at which we stopped, and no reports of foliar diseases have come to me since my last update (10-Apr). As you can tell from the reports below from Texas, there just is not much inoculum south of us to be carried northward, and what does blow up is likely not finding an environment conducive to infecting.
Our diagnostic lab has received few samples. Of two recent samples from Garfield County (north-central OK), one was positive for Wheat streak mosaic virus (WSMV) and the other was positive for WSMV and High plains virus. The diseases caused by these viruses, which are transmitted by the wheat curl mite, were fairly widespread in Oklahoma in 2013 and probably will be again in 2014. However, I suspect that the drought and freeze will mask these infections.
Reports/excerpts of reports from other states:
Texas Dr. Ron French (Ast Prof, Extn Plant Pathologist, Texas A&M AgriLife Extn Service) 25-Apr-2014: Was driving all day and night (600 miles) yesterday looking at crops from Castroville to the Lower Rio Grande Valley and back. Today heading back to Amarillo. Last Tuesday April 15 I drove from Amarillo to Wichita Falls (Northern Central part of the state right along the Oklahoma border) and back to Amarillo (220 miles NW of Wichita Falls). Looked at commercial wheat and some trial plots in Chillicothe.
Did not see any rust at all and brought samples back just to make sure. In the Wichita Falls area, wheat was at Feekes 10.4 (3/4 fully headed) on average. So now they should be at least flowering. In the Chillicothe area (65 miles NW of Wichita Falls towards Amarillo) wheat was on average at Feekes 10.3 (heading half complete). Have not heard of any rust in this area (Rolling Plains and Panhandle) this week.
I have not received any feedback of stripe rust moving north of Ellis County (from my April 10 report), although now it is also in Hill County, adjacent to Ellis, but in a SW direction. In Hill County, wheat with stripe rust was past pollination and into grain fill. Even in Bell county (Temple area, 120 miles south/southeast of Dallas) there was trace levels of stripe rust and none in the flag leaf. Except for the Texas Panhandle, all other areas will soon (early next week for the Vernon area) be out of the window for spraying any fungicides.
So the good news is that rust is not moving north, yet. With warm temperatures during the day but cool at night, this might be affecting continuous fungal growth for both stripe and leaf rust fungi.
Texas (from a report issued by Dr. Erick DeWolf at KSU 25-Apr-2014: Texas has reported some stripe rust activity just south of Dallas but warm temperatures have slowed the progress of that disease. Bob Bowden, USDA Plant Pathologist, reports that leaf rust remains active in research plots near San Antonio, Texas. However, the disease remains at low levels in commercial fields according to Tom Isakeit, Extension Plant Pathologist for Texas A&M. Wheat fields in southern Texas are nearly ready for harvest.
Kansas Dr. Erick DeWolf, Extension Wheat Pathologist, Kansas State University 24-Apr-2014: The risk of severe leaf diseases remains low throughout Kansas. My own scouting and reports from K-State agronomists indicate that leaf rust and stripe rust are not present in the state. Tan spot, septoria leaf blotch, and powdery mildew were absent in most fields; however, we did find a small number of fields with low levels of tan spot in Saline, McPherson, and Sedgwick counties. These fields all had wheat residue from previous crops on the soil surface. This residue is important because it often harbors the fungus that causes tan spot.
Drought stress was evident in most fields and the dry conditions are holding disease in check for now. Recent rains have brought some temporary relief to the dry conditions in a few areas of the state. We will continue monitoring the disease situation as this moisture may stimulate some disease. The symptoms of any new infections would not become evident for 7-10 days. The current risk of severe disease in Kansas and the need for foliar fungicides is low.