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osuwheat

osuwheat

Since 2004 I have served as the Small Grains Extension Specialist at Oklahoma State University. I work to improve the profitability and sustainability of small grains production in the southern Great Plains through improved management and variety selection. Most of my work focuses on dual-purpose and grain-only wheat production.

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Wheat disease update – 17 April 2015

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

Oklahoma:  This past week has been wet and cool across most of Oklahoma, which has greatly helped the wheat but also should lead to more foliar diseases – especially stripe and leaf rust.  Around Stillwater, we have not seen a big increase in stripe rust yet, but can find many leaves beneath the flag leaf on which there are actively sporulating pustules.  There also are leaves on which the black spore structure stage of stripe rust has appeared (called the telial stage – see photo – note actively sporulating pustules towards the base of the leaf).  Typically this indicates the disease is “shutting down,” which it was prior to this week.  However, with the cool and wet weather since Monday, there likely will be a “reactivation” of stripe rust – especially given that cool and wet weather is forecast for the next 5-10 days as well!

The black spore structure stage (telial stage) of stripe rust. Note actively sporulating pustules towards the base of the leaf.

The black spore structure stage (telial stage) of stripe rust. Note actively sporulating pustules towards the base of the leaf.

I get the impression from talking to Aaron Henson (County Educator; Tillman County) as well as other growers and consultants around the state that this is similar to what they are seeing.  Wheat seems to range from boot to heads emerging, so if you are contemplating applying a fungicide to protect a promising wheat yield, I suggest it be done soon.  Remember, GS 10.5 (heads fully emerged but not yet flowering) is the cut-off for applying fungicides for wheat foliar diseases.  That point likely is not far away for much of southern and central Oklahoma.  It likely is a bit farther away for northern and northwestern Oklahoma, but it is much better to apply a fungicide a little early rather than after the flag leaf is infected.

Most of the samples that came into the Diagnostic lab last week tested positive for wheat streak mosaic (WSM), including three from the panhandle.  However, there is nothing that can be done about WSM at this point.  I would refer you to EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and Triticum Mosaic:  Three Virus Diseases of Wheat in Oklahoma) available at www.wheat.okstate.edu for more information on these mite-transmitted viruses.

Reports/excerpts of reports from other states:

Colorado  Dr. Scott Haley (Professor & Wheat Breeder, Colorado State University) 16-Apr-2015:  “FYI, stripe rust was confirmed for a field site near the Denver International Airport in Colorado this week. Infection was moderate but cool wet weather we are experiencing now could cause this to increase. This is pretty early for stripe rust sightings in eastern Colorado.”

Northwestern / north central Oklahoma wheat update – drought, greenbugs, and freeze

Dr. Hunger traveled southwest Oklahoma this week, so I made a trip out Hwy. 60 yesterday to evaluate freeze injury and assess the overall condition of the wheat crop in northwestern and north central Oklahoma. Last week’s warm temperatures and wind have taken their toll on wheat in Kay, Grant, and eastern Garfield Counties. It is not too late for rain to save a partial wheat crop in these areas, but the “full yield potential” ship sailed long ago. Wheat sown behind summer crops is the hardest hit, and wheat in these fields could best be described as yellow and thin. If the weather turned and we received rain in the next week, I would predict that yield potential in these fields would still only be around the 15 bushel mark. Without rain, subtract around 15 bushels. Wheat planted behind summer fallow has held on a little longer, but is clearly showing the signs of extreme drought stress. If we receive rain in the next week (and continue to see rain) these fields could still make 20 – 30 bushels per acre. In the absence of rain in the near future, they will be 10 bushels per acre or less.

Wheat in the Lamont test plot was approximately GS 7 - 8. Flag leaves were rolled and plants were starting to abort tillers.

Wheat in the Lamont test plot was approximately GS 7 – 8. Flag leaves were rolled and plants were starting to abort tillers.

 

In addition to drought stress, we found freeze injury and greenbugs at Lamont. I was a little surprised to find freeze injury and even more surprised to find the greatest injury in the later-maturing varieties. We split several stems of early varieties such as Ruby Lee and Gallagher and did not find any injury. These varieties would have likely been at approximately GS 7 – 8 when the freeze occurred. We found significant injury in later-maturing varieties such as Endurance, but these varieties were likely only GS 6 – 7 when the freeze occurred. Conventional wisdom regarding freeze injury is that the more advanced the variety, the greater the likelihood of freeze injury. After seeing the same phenomenon last year (i.e. the greatest injury in later maturing varieties) I am changing my thinking on freeze injury and now say that all bets are off when it comes to freeze injury in drought stressed wheat.

Freeze injury was greatest in late-maturing varieties at Lamont.

Freeze injury was greatest in late-maturing varieties at Lamont.

 

Overall wheat condition started to improve around Nash and Jet, I would say that much of the wheat in this area is CURRENTLY in fair to good condition. I emphasize the currently in the previous sentence, as the only difference between wheat in the Cherokee area and wheat to the east was about one week’s worth of moisture. Some terrace ridges had already started turning blue and moisture was starting to run out. Without rain wheat in this area will rapidly deteriorate from good to poor. One consistent theme throughout the day was greenbugs. Many sites had evidence of parasitic wasp activity (i.e. aphid mummies), but the presence or absence of parasitic wasp activity varied field by field. Dr. Royer has indicated that greenbugs still need to be controlled in drought stressed wheat. If parasitic wasps are active, the best decision is to let them do the aphid killing for you. If no mummies are present, then insecticide control could be justified. The only sure way to make this determination is to use the glance-n-go sampling system.

 

Greenbugs were alive and well at Lamont

Greenbugs were alive and well at Lamont

Parasitic wasps were keeping greenbug populations under control in this field

Parasitic wasps were keeping greenbug populations under control in this field

Active and parasitized greenbugs on the same plant

Active and parasitized greenbugs on the same plant

 

Similar to Lamont, we found freeze injury in the Cherokee and Helena areas. Many of the worst looking fields (extensive leaf burn) had only superficial injury and should recover if moisture allows. Conversely, some plants that showed no outward signs of freeze injury had injured heads within.  Most fields I surveyed had less than 10% injury, but one field was a complete loss. On the surface the 10% injury field and 100% loss field looked the same, so I cannot over stress the importance of splitting stems. I have received a few additional reports of freeze injury from Kay County this morning, so it is important for producers throughout northern Oklahoma to evaluate their wheat on a field by field basis.

 

Plants that look healthy on the exterior could contain damaged wheat heads

Plants that look healthy on the exterior could contain damaged wheat heads

A closeup of the damaged wheat head from the picture above

A closeup of the damaged wheat head from the picture above

Although freeze injury to plant tissue in this field was severe, the wheat heads were mostly left unscathed

Although freeze injury to plant tissue in this field was severe, the wheat heads were mostly left unscathed

A closeup of a head from the freeze-injured wheat shown above. Although tissue damage is severe, the growing point and wheat head are still viable

A closeup of a head from the freeze-injured wheat shown above. Although tissue damage is severe, the growing point and wheat head are still viable

A final note on freeze injury. Freeze injury appeared to be worst in no-till fields and in areas where residue was heaviest. Based on my observations, this was not due to winterkill or poor seed to soil contact. My best explanation is that the lack of soil cover in conventional till fields allowed stored heat to radiate from the soil surface and slightly warm the crop canopy. The insulating effect of residue in no-till fields did not allow radiant heating to occur. Given the pattern of freeze injury in fields with varying degrees of residue across the field, I feel pretty confident in this analysis of what occurred.

Please use the comment section to share pictures or descriptions of wheat in your area.

Wheat disease update – 09 April 2015

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

Oklahoma: On April 6, I traveled a route from Clinton (85 miles west of OKC) in west central Oklahoma going northeast through Custer County to Kingfisher (40 miles northwest of OKC) and then to Marshall (35 miles west of Stillwater). Although there was some good wheat on this route (e.g. the variety trials at Kingfisher and Marshall), it is posed to decline quickly unless rain is received. Most of the wheat I looked at in Custer County northeast of Clinton was small and fields were terribly dry. Wheat in this area seemed to be at GS 6-7 and I’m guessing was planted quite late due to the dry fall. The most common problem I saw were greenbug, especially in Custer County. However, as the photos show, there were many mummies present indicating the population should be crashing shortly. I also saw some stripe rust but only an infection here and there. Around the variety trial at Kingfisher, wheat was mostly around GS 9 and I saw no aphids or disease. At Marshall, wheat was at GS 8 and there was some stripe rust but at a low incidence.

Greenbugs and mummies in Custer County, Oklahoma

Greenbugs and mummies in Custer County, Oklahoma

On April 7, I traveled to Frederick in south central OK looking at wheat along the way. At a variety demo 20 miles west of OKC right at I-40, I found the wheat at GS 8 with just a little touch here and there of stripe rust. Soil moisture here looked good; this area must have caught a decent rain in the last week or so. The same could be said at another variety demo straight south about 15 miles south at Minco. Here the wheat in the field surrounding the demo was at GS 9, there was good soil wetness, and the wheat looked good. I did not see any rusts or powdery mildew, but there were occasional BYD spots. Further southwest near Apache (30 miles north of Lawton) wheat was at GS 9-10 and looked very good in the variety trial as well as in fields. However, some leaves were beginning to roll and the need for moisture to continue the crop was evident. I didn’t see any aphids or diseases in wheat west of Apache, but I the variety trial just south of Apache I found some stripe rust and greenbug; both at a very low incidence.

Wheat stripe rust

Wheat stripe rust

The rest of this trip was spent with Aaron Henson (Extension Educator, Tillman County) and Mark Gregory (Area Extn Agron Spec – SW Oklahoma) looking at wheat in Tillman County. Wheat in this area was mostly at GS 9-10 with awns occasionally just emerging from the boot. Some fields we visited were dry and impacted by drought, while others looked good but needed another drink soon. A few fields were outstanding and had good soil moisture. One field in particular was the best wheat I have seen since 2012. It was a field of Ruby Lee that was at GS 10 and had been sprayed on 15-Mar because of reports of severe stripe rust in the area and in northern Texas to the south. A 20 ft strip of unsprayed wheat was left on the outside of the north and west side of the field because of power lines and wind. This strip served as an excellent control to indicate the effect of the spray. The line between sprayed and not- sprayed was visible from the road and even more evident in the field (see photos). Within the not-sprayed strip, flag leaves were green with leaves beneath the flag hit hard with stripe rust (see photos). The field was sprayed a second time on 05-Apr because it has such good potential. Leaves in the sprayed area are completely green. I have difficulty explaining the complete lack of stripe rust on the flag leaves in the not-sprayed area. Likely the flag leaves were not yet emerged at the time of the first spray and then conditions after spraying did not allow spread of stripe rust to them. However, in talking to Aaron and Mark it seems there were conditions after the 15-Mar spraying that would have been conducive for spread of stripe rust. At any rate, this is an excellent example of how a timely spray did a tremendous job of protecting yield potential.

Stripe rust – note yellow cast to wheat in foreground that changes to deep green about halfway into phot

 

Signs of stripe rust were present in the lower canopy, but stripe rust was not present on flag leaves

Signs of stripe rust were present in the lower canopy, but stripe rust was not present on flag leaves

Fungicide-treated Ruby Lee in the same field as above photos

Fungicide-treated Ruby Lee in the same field as above photos

 

Other diseases observed across the Oklahoma include wheat streak mosaic, which has been detected in samples from several places including around Stillwater and from Noble County just north of Payne County (where Stillwater is located). However, I have not received indication yet of severe WSM; part of this may be related to the drought in western OK where WSM is typically more common. Recently samples from northwestern OK are beginning to come into the diagnostic lab, but results from some of those samples are still pending.

 

Reports/excerpts of reports from other states:

Texas Dr. Charlie Rush (Professor, Texas A&M AgriLife Research, Amarillo) 3-Apr-2015: “I haven’t checked all fields as closely as those around Bushland but there are a lot of GB and Russian wheat aphids as well as bird cherry.  Russian seems predominate in my fields.  We sprayed last week but will likely sustain significant yield loss from not spraying earlier.  I suspect we’ll start getting lots of calls and samples that end up being BYDV, although some WSM is also showing up.  Mild winter with more moisture than last few years has resulted in a crop that has looked very promising up to now but without good subsoil moisture what we had in the upper layers of the soil profile is disappearing fast and obvious symptoms of drought are beginning to appear.”

Greenbug infestations reported

By Tom Royer, OSU Extension Entomologist

I received several reports of treatable greenbug infestations in winter wheat in Major County. This means it is important to scout your fields for greenbugs. I encourage you to use the “Glance n’ Go system, as it is easy to use.

Greenbugs on wheat

Greenbugs on wheat

There are several things that make Glance ‘n Go sampling a desirable way to make such a decision. You only have to “Glance” at a tiller to see if it has greenbugs (no counting greenbug numbers). You can make a decision to treat “on the Go” because you stop sampling once a decision is reached (no set number of samples). Finally, you can account for the activity of the greenbug’s most important natural enemy, Lysiphlebus testaceipes. Aphid Mummies

The Glance ‘n Go system be accessed in two ways. One is to set up an account with the myFields platform: http://myFields.info and sign up for a personal account. This system will allow you to sample a field with a smart phone in the field. To use it, you must have cell phone connectivity. You can then select the Glance n’ Go tool, plug in your cost inputs, and start sampling. Once you sign up, you can scout multiple fields and myFields will keep track of all your sampling information.

Glance-N-Go using the myFields platform

The second way is to access the Cereal Aphids Decision Support Tool on your computer http://entoplp.okstate.edu/gbweb/index3.htm . You can customize the threshold and selecting the Greenbug Calculator. Put your inputs in and it will select a threshold for your field. You can then download a paper Glance n’ Go form; take it to the field and start scouting.

Cereal Aphids Decision Support Tool

Cereal Aphids Decision Support Tool

By answering a few simple questions, you can determine an economic threshold for controlling greenbugs. This threshold is based on the estimated cost of treating the field and the estimated price of wheat. Once a threshold is calculated, you can print a Glance ‘n Go scouting form, take it to a field and record your sampling results. The form will help you to decide if the field needs to be treatment for greenbugs.

When scouting with the Glance ‘n Go system, keep a running count of tillers that have one or more aphid mummies and a running count of tillers that are infested with one or more greenbugs. The Glance ‘n Go form directs you to look at your total number of infested tillers and tillers with mummies after 5 stops. You will be directed to treat, not treat, or continue sampling. If there is enough parasitoid (mummy) activity, you will be directed to stop sampling and DON’T TREAT, even if you have exceeded the treatment threshold for greenbugs! Why? Because research showed that at that level of parasitism, almost all of the healthy-looking greenbugs have been “sentenced to death” and will be ghosts within 3-5 days. If they have received their “sentence” you can save the cost of an unnecessary insecticide application.

aphid mummies

aphid mummies

I accessed the Glance n’ Go tool to determine a “general” threshold that you can use for a Spring infestation, based on a wheat price of $5.50 per bushel and an application cost of either $4, $6, and $8 per acre. You can go directly to the website and download a paper form (Greenbug Spring Infestation) directly. The threshold is 3 greenbugs per tiller if your application costs are $4 per acre or 2 greenbugs per tiller for application costs of $6 or $8 per acre.

Contact your local County Extension Agricultural Educator for more information. If a field needs to be treated, check with Current Report CR-7194, “Management of Insect and Mite Pests in Small Grains”.

First hollow stem update 03/16/15

First hollow stem is the optimal time to remove cattle from wheat pasture (full explanation). To monitor first hollow stem, we measure hollow stem for the 56 lines in our September-sown wheat forage plots at Stillwater each year. Almost all varieties are well past first hollow stem. Full results are posted in the table below. Varieties with no value for first hollow stem reached first hollow stem on a previous measurement date.

This will be the last first hollow stem update of the 2015 season. You can check progression of first hollow stem around the state by using the First Hollow Stem Advisor on the Oklahoma Mesonet site

First hollow stem measured in wheat sown 09/16/2014 at Stillwater, OK. Varieties with ‘-‘ reached first hollow stem on a previous measurement date
Variety cm of hollow stem 03/16/15
Endurance 0.9
Deliver 1.7
Pete 0.3
OK Rising 1.1
Billings
Ruby Lee 2.1
Garrison 1.9
Duster
Gallagher
Iba
Centerfield 1.0
Doublestop CL Plus 1.5
NF 101
Everest
1863
KanMark 3.0
Oakley CL 2.1
KS061406
Sy Llano
Sy Southwind
Greer
Jackpot
Sy Monument 2.1
06BC722#25
AP09T7631
WB-Cedar
WB-Redhawk
WB4458
WB-Grainfield
Winterhawk
T153
T154
T158 2.4
LCS Mint
LCS Wizard
LCS Pistol
LCH13DH-20-87 6.0
LCH13DH-14-91
TAM 112
TAM 204
TAM 113
TAM 114
CO11D174 .
Byrd
Brawl CL Plus
OK09125
OK1059060-2C14
OK10126
OK11D25056 1.8
OK11231
OK12621 3.9
OK13625
OK0986130-7C13
OK08P707W-19C13 3.8
OK10728W
OK11755W

 

 

Wheat disease update – 16 March 2015

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

Oklahoma:  The leaf rust I saw around Stillwater in February seems to have “died out.”  The cold weather we had from late February into early March killed the lower leaves where leaf rust was active and conditions did not allow spread to younger leaves.  Dr. Brett Carver (OSU Wheat Breeder) confirmed this to me this morning as he indicated late last week he did not see any rust (leaf or stripe) around Stillwater or at his nurseries in Lahoma and Marshal.  This also is the case for northern and northwestern OK, as well as for KS (see Dr. De Wolf’s observations under “Other States” below).  Dr. Tom Royer and I visited variety trials at Cherokee and Alva last week.  No foliar diseases were observed but Dr. Royer did find a small greenbug colony on wheat in the field surrounding the Alva trial.  However, with mild temperatures and moisture predicted for the coming week and with inoculum to the south of us in Texas and southern Oklahoma, foliar diseases should be increasing in incidence and severity across central and northern OK.

Leaf and stripe rust are active in Texas (see Dr. Ron French’s observations below), and southern and central Oklahoma.  Mark Gregory (Area Extn Agron Spec – Duncan, OK) has reported seeing both leaf and stripe rust (but more stripe rust) across much of south-central and southwestern OK – especially around Grandfield, OK located north of Wichita Falls, TX.  Similar reports have come from Aaron Henson (Extn Educator; Tillman Cnty) and Gary Strickland (Exten Educator; Jackson Cnty).  Incidence has ranged from scattered to many “hot spots” of stripe rust, and from light to intermediate incidence of leaf rust.

Some of these fields (especially if it is a susceptible variety) will merit an early application of fungicide to curtail foliar disease activity (especially the stripe rust).  Be aware that applying a fungicide now will not last the entire season, and a second application toward head emergence also may be needed if weather continues to be favorable for foliar diseases.  For an early season application I recommend using a full rate (as opposed to a half rate) of a less expensive fungicide because there is so much time left in the growing season.  Then a later season application with a more expensive fungicide may or may not be needed.  Also be sure to not exceed the maximum amount of fungicide applied and to rotate chemistries to prevent resistance. Also consider your variety.  A variety like Ruby Lee that has good yield potential should be protected from early and late stripe or leaf rust, but a variety such as Duster may show some leaf rust early but still has good resistance to this rust.  However, stripe rust on Duster may merit control.  ALSO, in no-till fields watch for incidence of diseases such as tan spot, septoria, and powdery mildew as these diseases likely will be more common in fields with wheat residue and may merit an early season fungicide application.

Reports/excerpts of reports from other states:

Texas  Dr. Ron French (Ast Prof & Extn Plant Pathologist, Texas A&M AgriLife Extension Service, Amarillo) 9-Mar-2015:  “Last week, I was visiting the lower Coastal Bend of Texas (around Kingsville/Corpus Christi) and the Lower Rio Grande Valley of Texas (along the southernmost part of the Texas-Mexico border area). In Weslaco (Hidalgo County, Lower Rio Grande Valley), I visited sentinel plots (21 lines-winter wheat, spring wheat, barley…).”

“In Weslaco (March 4), Puccinia graminis f. sp. tritici, the causal agent of stem rust, was found on leaf tissue only, at trace levels to 1% severity in six 6 lines including  Morocco,  Marvelous, Kyto (CI 8250) and Line B (1% severity). Last year, stem rust was first observed on Siouxland, Panola, and  Morocco but observations were done the week of April 7, 2014.”

“Stripe rust (March 3)on wheat was observed  in 5 lines, ranging from  trace levels in Siouxland  to 25% incidence and 40% severity on Sisson.  Leaf rust was only observed at trace levels in lines such as Siouxland, Panola, and Sisson.  Powdery mildew was only present in the lower canopy of barley  Hypana, Morex DPH, and Hyproly.  Some wheat was already in the boot stage (Morocco, Line B).”

“Last year, dry conditions (little or no rain) were present in this area when stem rust was first observed. This year has seen more rain during the past three weeks, with temperatures ranging from as low as 38° F to as high as 84°F (lower on average for that area). With rain and warmer weather expected this week, disease pressure may be more conducive to seeing more disease development for all rusts.”

“No stem rust was observed in wheat in  the lower coastal bend around Kingsville, approximately 110 miles north of Weslaco. Fields did have stripe rust (up to 20% severity) but had already been sprayed with a fungicide and trace levels of leaf rust could also be observed.”

Kansas  Dr. Erick De Wolf (Prof & Small Grains Extn Pathologist, Kansas State Univ) 11-Mar-2015:  “We did some scouting for rust diseases near Manhattan (Northeastern KS).  We were checking on research plots where rust had been noted last fall but were unable to detect leaf rust in these plots so far this spring.  We noted severe tip die-back of the leaf tissue in these plots and suspect that this winter injury has removed much of the leaf rust from this location. Bethany Grabow, Ph.D candidate with KSU detected a trace of leaf rust on wheat in an adjacent field.  Incidence of disease was <0.01% with only a few pustules detected. This wheat was planted later than the aforementioned plots and did not experience the winter injury to the leaf tissue.  We also noted small colonies of aphids in the research plots with each colony having 3-5 aphids a few winged aphids were also observed near the colonies. We will continue to monitor the diseases this spring and provide more updates soon.”

Wheat leaf rust

Wheat leaf rust

Wheat stripe rust

Wheat stripe rust

First hollow stem update 03/12/15

First hollow stem is the optimal time to remove cattle from wheat pasture (full explanation). To monitor first hollow stem, we measure hollow stem for the 56 lines in our September-sown wheat forage plots at Stillwater each year. In spite of the recent cold snap many varieties are progressing towards first hollow stem. The small grains extension crew split ten stems from lines tested in our program today and Billings, Duster, Iba, Oakley CL, Hot Rod (formerly KS061406), WB Greenfield, and LCS Wizard join the list of varieties at or past first hollow stem. Full results are posted in the table below. Varieties with no value for first hollow stem reached first hollow stem on a previous measurement date.

We will take another set of measurements early next week and report the results on this blog. You can check progression of first hollow stem around the state by using the First Hollow Stem Advisor on the Oklahoma Mesonet site.

 

First hollow stem measured in wheat sown 09/16/2014 at Stillwater, OK. Varieties with ‘-‘ reached first hollow stem on a previous measurement date
Variety cm of hollow stem 03/12/15
Endurance 0.2
Deliver 1.0
Pete 0.6
OK Rising 1.1
Billings 1.6
Ruby Lee 0.9
Garrison 1.2
Duster 1.8
Gallagher
Iba 1.7
Centerfield 0.8
Doublestop CL Plus 1.4
NF 101
Everest
1863
KanMark
Oakley CL 2.0
Hot Rod 2.8
SY Llano
SY Southwind
Greer
Jackpot
SY Monument 1.2
SY Flint
SY Drifter
WB-Cedar
WB-Redhawk
WB4458
WB-Grainfield 2.0
Winterhawk
T153
T154
T158 0.9
LCS Mint
LCS Wizard 1.5
LCS Pistol
LCH13DH-20-87 2.6
LCH13DH-14-91
TAM 112
TAM 204
TAM 113
TAM 114
CO11D174
Byrd
Brawl CL Plus
OK09125 1.9
OK1059060-2C14 1.6
OK10126
OK11D25056 1.1
OK11231
OK12621 1.2
OK13625
OK0986130-7C13
OK08P707W-19C13 1.3
OK10728W
OK11755W

 

 

 

First hollow stem update 03/09/15

First hollow stem is the optimal time to remove cattle from wheat pasture (full explanation). To monitor first hollow stem, we measure hollow stem for the 56 lines in our September-sown wheat forage plots at Stillwater each year. In spite of the recent cold snap many varieties are progressing towards first hollow stem. The small grains extension crew split ten stems from lines tested in our program today and KanMark, Sy Southwind and Greer join the list of varieties at or past first hollow stem. Full results are posted in the table below. Varieties with no value for first hollow stem reached first hollow stem on a previous measurement date.

We will take another set of measurements later this week and report the results on this blog. Given the warm forecast for the coming week, I predict that all varieties will be well past first hollow stem by Friday. You can check progression of first hollow stem around the state by using the First Hollow Stem Advisor on the Oklahoma Mesonet site.

 

First hollow stem measured in wheat sown 09/16/2014 at Stillwater, OK. Varieties with ‘-‘ reached first hollow stem on a previous measurement date
Variety cm of hollow stem 03/09/15
Endurance 0.2
Deliver 0.2
Pete 0.3
OK Rising 0.7
Billings 1.0
Ruby Lee 0.6
Garrison 0.9
Duster 0.9
Gallagher
Iba 0.8
Centerfield 0.5
Doublestop CL Plus 0.6
NF 101
Everest
1863
KanMark 1.5
Oakley CL 0.9
KS061406 1.2
Sy Llano
Sy Southwind 2.6
Greer 2.1
Jackpot
Sy Monument 0.7
06BC722#25
AP09T7631 1.5
WB-Cedar
WB-Redhawk
WB4458
WB-Grainfield 0.8
Winterhawk
T153
T154
T158 0.8
LCS Mint
LCS Wizard 0.6
LCS Pistol
LCH13DH-20-87 1.0
LCH13DH-14-91
TAM 112
TAM 204
TAM 113
TAM 114
CO11D174 2.2
Byrd
Brawl CL Plus
OK09125 1.3
OK1059060-2C14 0.9
OK10126
OK11D25056 1.1
OK11231
OK12621 1.1
OK13625
OK0986130-7C13
OK08P707W-19C13 1.4
OK10728W
OK11755W

 

Army cutworms reported in some Oklahoma wheat fields

This article is provided by Dr. Tom A. Royer, OSU Extension Entomologist

Sug Farrington, Extension Educator in Cimarron County received a sample of “worms” that were collected by a producer in his wheat field. They turned out to be army cutworms.

Unlike the fall armyworm, this caterpillar overwinters in Oklahoma, tolerates cold and feeds throughout the winter months. Adult army cutworm moths migrate to Oklahoma each fall from their summer residence in the Rocky Mountains. They seek bare or sparsely vegetated fields (like a newly prepared field ready for wheat planting, or a field that was “dusted in” and had not yet emerged) and lay eggs from August through October. The eggs hatch soon after being deposited, which explains why a producer might see different sizes of larvae in a field. Army cutworms feed throughout the winter and molt seven times before they turn into pupae in the soil. Most larvae will be gone by late March and adult moths begin emerging in April and fly back to the Rocky Mountains to spend the summer.

Army cutworms. Photo courtesy Sug Farrington, Cimarron County Extension Educator.

Army cutworms can cause severe stand loss of wheat if not controlled. Cutworm damage often goes unnoticed through the winter because the caterpillars grow slowly and don’t get big enough to cause noticeable damage until temperatures warm in the spring. Unfortunately, that is also an indication of poor growing conditions due to drought (which cutworms also like), so it becomes important to check the fields for cutworms. If you notice a field at this time of year with a numbers of starlings or black birds feeding in a concentrated area of your wheat field, they are likely feasting on army cutworms!

Army cutworm injury in wheat. Photo courtesy Sug Farrington, Cimarron County Extension Educator.

Army cutworm injury in wheat. Photo courtesy Sug Farrington, Cimarron County Extension Educator.

Sample a field by stirring or digging the soil to a depth of two inches at 5 or more locations. Also, turn over those dried up cow patties, as they are a favorite hiding place for army cutworms. The cutworms will be “greenish grey”, and will probably curl up into a tight “C” when disturbed. A suggested treatment threshold is 2-3 caterpillars per foot of row when conditions are dry (like we are experiencing this winter) or 4-5 caterpillars per row-foot in fields with adequate moisture. Control suggestions are listed in Current Report-7194 Management of Insect and Mite Pests in Small Grains.

Army cutworms are also a potential pest of canola. Scout fields just as you would in wheat. The suggested treatment threshold for cutworms in canola is 1-2 per row-foot. Current recommendations for control of army cutworms in canola are listed in CR-7667, Management of Insect and Mite Pests in Canola.

First hollow stem update 03/05/15

First hollow stem is the optimal time to remove cattle from wheat pasture (full explanation). To monitor first hollow stem, we measure hollow stem for the 56 lines in our September-sown wheat forage plots at Stillwater each year. In spite of the recent cold snap many varieties are progressing towards first hollow stem. The small grains extension crew split ten stems from lines tested in our program today and1863, LCS Mint, TAM 204, TAM 113, TAM 114, and Byrd join the list of varieties at or past first hollow stem. Full results are posted in the table below. Varieties with no value for first hollow stem reached first hollow stem on a previous measurement date.

We will take another set of measurements later this week and report the results on this blog. Given the warm forecast for the coming week, I predict that all varieties will be well past first hollow stem by next Friday. You can check progression of first hollow stem around the state by using the First Hollow Stem Advisor on the Oklahoma Mesonet site.

 

First hollow stem measured in wheat sown 09/16/2014 at Stillwater, OK. Varieties with a “-” reached first hollow stem on a previous measurement date
Variety cm of hollow stem 03/05/15
Endurance 0.2
Deliver 0.2
Pete 0.1
OK Rising 0.2
Billings 0.7
Ruby Lee 0.6
Garrison 0.5
Duster 0.5
Gallagher
Iba 0.5
Centerfield 0.2
Doublestop CL Plus 0.3
NF 101
Everest
1863 1.6
KanMark 1.1
Oakley CL 0.6
KS061406 1.0
Sy Llano
Sy Southwind 0.9
Greer 1.1
Jackpot
Sy Monument 0.1
06BC722#25 2.8
AP09T7631 1.1
WB-Cedar
WB-Redhawk
WB4458
WB-Grainfield 0.8
Winterhawk
T153
T154
T158 1.3
LCS Mint 1.5
LCS Wizard 0.7
LCS Pistol
LCH13DH-20-87 1.1
LCH13DH-14-91
TAM 112
TAM 204 1.6
TAM 113 1.6
TAM 114 1.9
CO11D174 1.1
Byrd 1.7
Brawl CL Plus
OK09125 0.8
OK1059060-2C14 1.4
OK10126
OK11D25056 0.9
OK11231
OK12621 0.8
OK13625
OK0986130-7C13
OK08P707W-19C13 1.3
OK10728W 1.5
OK11755W
Average 1.0

 

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