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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

 

First hollow stem update 03/02/15

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 NF 101 and Brawl CL Plus join the list of varieties at or past first hollow stem. Full results are posted in the table below. We will take another set of measurements later this week and report the results on this blog.

The numbers reported from Stillwater are likely behind those being observed in southern Oklahoma and ahead of those observed in northern Oklahoma. 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.
Variety cm of hollow stem 03/02/15
Endurance 0.5
Deliver 0.4
Pete 0.1
OK Rising 0.1
Billings 0.4
Ruby Lee 0.2
Garrison 0.1
Duster 0.4
Gallagher .
Iba 0.1
Centerfield 0.1
Doublestop CL Plus 0.1
NF 101 1.5
Everest .
1863 0.6
KanMark 0.4
Oakley CL 0.6
KS061406 0.7
Sy Llano .
Sy Southwind 0.2
Greer 0.8
Jackpot .
Sy Monument 0.4
06BC722#25 1.3
AP09T7631 0.4
WB-Cedar .
WB-Redhawk .
WB4458 .
WB-Grainfield 1.1
Winterhawk .
T153 .
T154 .
T158 0.5
LCS Mint 0.8
LCS Wizard 0.9
LCS Pistol .
LCH13DH-20-87 0.8
LCH13DH-14-91 .
TAM 112 .
TAM 204 1.4
TAM 113 1.2
TAM 114 1.4
CO11D174 0.9
Byrd 0.7
Brawl CL Plus 1.8
OK09125 0.5
OK1059060-2C14 0.7
OK10126 .
OK11D25056 0.7
OK11231 2.2
OK12621 0.9
OK13625 .
OK0986130-7C13 .
OK08P707W-19C13 1.2
OK10728W 1.0
OK11755W .
Average 0.7