Central Great Plains HWW Region's blog

FHB Update from KS, 06/20/19

There are multiple reports of Fusarium head blight in parts of Central and Eastern Kansas. There are only reports of low levels of FHB from Western Kansas to date. The disease in Central and Eastern KS likely corresponds to infections that took place in the middle of May. The wheat in Kansas is maturing rapidly and will soon be ready for harvest. Growers in the Central and Eastern regions should be setting harvest priorities to focus on fields with the lowest disease levels, planning to adjust combines during harvest to clean out visibly scabby kernels, and making arrangements to segregate loads of heathy grain from those with less desirable levels of disease where possible.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from OK, 05/31/19

Harvest in southern OK started just this week, so this report will focus primarily on wheat in central, northern, northwestern and the panhandle of Oklahoma. It appears that the wheat crop is well along in its development and needs some dry and warmer weather to finish (as well as to allow harvest!). The primary issues this past week have been deterioration of leaves and head discoloration. The wet environment certainly is contributing to both of these issues. In wheat around Stillwater, heads are being discolored due to black chaff (a bacterial disease) as well as Septoria/Stagonospora that cause leaf spotting as well as head discoloration. There also is a general darkening of heads, called melanism, which results not from a disease but rather is related to genetics and environment. This melanism is difficult to distinguish from the other diseases that are present, especially because this year there seems to be all these happening at once.

Other diseases that are likely to be observed at this point in time are white heads due to foot rots (see wheat disease update on 5-24-2019 available at http://entoplp.okstate.edu/pddl/advisory.htm), Fusarium head blight, and sooty mold. I’ve described and discussed Fusarium head blight in a previous update (5-16-2019 available at http://entoplp.okstate.edu/pddl/advisory.htm). Sooty mold on heads occurs when wheat has turned but cannot be harvested in a timely manner. Wet and humid conditions promote fungal growth on those heads (Figure 4). With time, these fungi can also partly start to grow on wheat seed still in the head, especially at the germ end of the seed. This can lead to a poorer quality of wheat and reduced seed germination

What is described above is confirmed for northwestern OK and the OK panhandle by Josh Bushong (NW OK Area Extn Agron Speclt) who reported seeing overall leaf health as deteriorating across NW OK as well as at field days this past week at Hooker, Balko and Goodwell (all in the OK panhandle). However, the wheat in these parts of Oklahoma should be sufficiently far along (mostly in dough stage) so that the impact on yield should be minimal. Be aware though that head diseases such as Fusarium head scab and sooty mold can affect grain quality and create major problems when the wheat is taken to the elevator.

--Bob Hunger, Extension Plant Pathologist, Oklahoma State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from OK, 05/16/19

I started this past week on Monday (13-May) at the variety trial at Chickasha, OK, where wheat was mostly full kernel watery to milky. Stripe rust was the most prevalent foliar disease, but overall was not extremely heavy in the variety trial. Septoria/Stagonospora was a close second to stripe rust, and actually was more widespread than stripe rust but for the most part was only on the lower and mid leaves. Leaf rust also was present, but overall seemed less than stripe rust. From Chickasha, I moved to Tipton, OK in southwestern OK where the wheat was mostly about soft dough. Leaves here were quickly turning and showed a combination of stripe rust, leaf rust, and Septoria/Stagonospora. However, varieties and lines with good resistance stood out. On Tuesday (14-May), I was at the field day near El Reno in central OK (25 miles west and a bit south of OKC). Wheat here was at the end of flowering to full kernel-watery. Overall diseases were light with Septoria/Stagonospora on lower and mid leaves and some stripe and leaf rust on upper leaves. Powdery mildew also was present, but mostly only on certain varieties. Next, a demonstration was visited near Minco, OK (about 20 miles west). This demo was planted quite late (early December), and was mostly at flowering. The foliar disease situation was basically the same, that is, some stripe and leaf rust along with some powdery mildew and Septoria/Stagonospora.

From Minco, I moved north to the variety trial at Kingfisher, OK (30 miles NW of OKC). The explosion of leaf rust at Kingfisher was impressive, and finally fit with my expectations for the occurrence of leaf rust this year.

Finally, there may be some additional diseases to watch for this year given the extended cool and wet spring. This includes several diseases, but primarily bacterial streak (black chaff) and Fusarium head blight (head scab). Dr. John Fenderson (Technical Product Manager; Bayer Crop Science-WestBred) indicated on 9-May that he observed major infections of bacterial streak across central Texas. Dr. Brett Carver (OSU Wheat Breeder) also indicated seeing symptoms consistent with bacterial streak at the field day near Okmulgee in eastern OK earlier this week. Symptoms of bacterial streak are somewhat similar to Septoria/Stagonospora, and could be overlooked if both are present. However, the head symptoms should be more discernable, and currently I have not seen symptoms such as this across central and western OK.

Fusarium head blight typically occurs in eastern/northeastern OK every year, and this spring has been favorable for this disease. Wheat heads will be totally or partially bleached and contain shriveled and often pinkish or salmon colored seed. To get more information on head scab, see OSU PSS-2145 (Fusarium Head Blight (Head Scab) of Wheat: Questions and Answers – available at http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-6307/PSS-2145...) and OSU PSS-2136 (Considerations when Rotating Wheat behind Corn – available at http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-5436/PSS-2136...). Another outstanding resource regarding Fusarium head blight is the “Fusarium Head Blight Prediction Center” at http://www.wheatscab.psu.edu/. At this site there are resources describing the disease as well an assessment tool that can be used to help predict when spraying is critical to help prevent Fusarium head blight.

--Bob Hunger, Extension Plant Pathologist, Oklahoma State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from KS, 05/16/19

Wheat in south central and central Kansas is at heading and flowering stages of development. Wheat in north central KS is now moving through the boot and heading stages of growth and will likely reach the critical growth stages in 5-7 days. The model is indicating moderate or high risk of severe disease as we move into the most vulnerable period of growth. The risk is likely to persist or increase if forecasts for rainfall and extended periods of high relative humidity develop as expected. Growers in central Kansas should be monitoring the situation carefully and planning to apply a fungicide if weather conditions remain favorable. Care should be taken to select an effective fungicide for management of FHB with Prosaro, Caramba and Miravis Ace.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from KS, 05/12/19

Wheat in southeastern and south-central Kansas is at heading and flowering stages of development. Wheat in central KS is now moving through the boot and heading stages of growth and will likely reach the critical growth stages in 3-5 days. The model is indicating moderate or high risk of severe disease just as we move into the most vulnerable period of growth. The risk is likely to persist or increase if these regions continue to receive frequent rainfall and extended periods of high relative humidity. Growers in southeastern and central Kansas should be monitoring situation carefully and planning to apply a fungicide if weather conditions remain favorable. Care should be taken to select an effective fungicide for management of FHB with Prosaro, Caramba and Miravis Ace being the best options. Many other fungicides are less effective or are not labeled for Fusarium suppression.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from OK, 05/09/19

This past week in addition to looking at wheat around Stillwater, Dr. Tom Royer (OSU Entomologist) and I were at field days on Monday (6-May) near Kildare in north-central OK (Kay County) followed by a stop at the Experiment Station near Lahoma (15 miles west of Enid) and another field day near Cherokee in Alfalfa County (north and west of Enid and about 20 miles south of KS). That was followed on Tuesday by a field day at Kingfisher (about 25 miles northwest of Oklahoma City) and field visits northwest of Kingfisher near Loyal. Across these areas wheat ranged from heading to full kernel formed (watery to start of milky). In southwestern OK, wheat ranges from ¼ kernel to milky whole kernels with the dough stages approaching quickly.

In southwestern OK, leaf rust, stripe rust and Septoria tritici blotch have become severe according to both Heath Sanders (SW OK Area Extn Agronomy Spclt) and Gary Strickland (Extn Educator; Jackson Cnty). Gary indicated that this is only the second time he has seen Septoria tritici blotch severe on flag leaves. Leaf rust also is severe. Both Heath and Gary also indicate they have started to see more powdery mildew in fields, but have found it severe on the mid and lower leaves in only one field.

In north-central OK near Kildare, wheat was mostly clean with Septoria tritici blotch being the most noticeable disease on lower leaves. No significant stripe or leaf rust was observed, and powdery mildew could be found but was sparse. By contrast, wheat at Lahoma showed significant leaf and stripe rust with leaf rust being the most prevalent. However, whereas the rusts could be found in many of the wheat breeding nurseries, both rusts were lacking in the large variety trial with stripe rust being present at only a low severity. In some varieties and breeder lines, leaves were quickly deteriorating. At Cherokee, heavy rain on Sunday had saturated the area and more rain fell on Wednesday. Rust was light in the variety trial with stripe rust again being the most prevalent albeit again at a low incidence and severity. At Kingfisher on Tuesday, leaf rust was the most prevalent foliar disease with Septoria tritici blotch also present on lower foliage. In a field near Loyal, OK, Dr. Royer found a high incidence of armyworms especially along the field’s edge. As he moved into the field, the incidence of worms dropped, but he felt like a field such as this was approaching the spray threshold and should be watched closely to monitor if the spray threshold was reached. For more information on armyworms in wheat, including threshold numbers and control options, see Pest eAlert Vol 18, No. 14, EPP-7094 “Common Small Grain Caterpillars in Oklahoma” and CR-7194, “Management of Insect and Mite Pests in Small Grains.”

In addition to army worms, a physiological leaf spot (PLS) was observed on wheat leaves around Kingfisher and Loyal. As indicated in my last update (http://entoplp.okstate.edu/pddl/2019/PA 18-16.pdf), PLS has been observed in a number of fields across several varieties. There can be many causes of PLS, one of which is chloride deficiency. Chloride deficiency tends to be variety specific. Years ago in Oklahoma, the varieties ‘Payne’, ‘Cimarron’ and ‘Century’ all would show PLS due to chloride deficiency. Cimarron and Century both had Payne as a parent in their pedigree. Hence, although chloride deficiency can cause a PLS, there are other causes as well, and this year I believe that the PLS being observed is too widespread and across to many varieties to be attributed to only a deficiency of chloride. For more information on chloride and its role in PLS, see Kansas State University’s recent extension publication MF 2570; Chloride in Kansas: Plant, Soil and Fertilizer Considerations (Dorivar A. Ruiz Diaz), which can be found at: https://www.bookstore.ksre.ksu.edu/pubs/MF2570.pdf

A report of increasing foliar disease also came in from Lanie Hale (Wheeler Brothers; west central OK) who reported, “In my last report April 26, I told you I found 3 fields with rust. Those 3 fields were out of a total of 23 fields scouted. Those 3 fields have been sprayed. Yesterday, May 6th, I looked at the 20 fields where I found no rust April 25th. 11 of those 20 had stripe rust and/or leaf rust. Since the 30 day window is upon us, the farmers are spraying all 20 fields. In the fields I looked at yesterday, I would estimate 75-80% of the flag leaves had some kind of dis-coloring issue ranging from light flecking to stripe rust, leaf rust, Tan Spot, or Septoria tritici blotch. (1&2) I noticed many of the stems have dark spots below the flag leaf; (2) I’m assuming that is also Septoria tritici blotch. Several fields had small circular spots that appear to be Barley Yellow Dwarf Virus hot spots. (3) The head count in all the fields I’ve scouted, regardless of the location, is tremendous. If we can maintain the flag leaf health we have today, yields and grain quality will also be tremendous.”

These and additional reporting by Josh Bushong (NW OK Area Extn Agronomy Spclt) all indicate that foliar wheat diseases, especially Septoria tritici blotch, leaf rust, and stripe rust are increasing greatly in incidence and severity across Oklahoma. With continued wet and cool weather, the incidence/severity of these diseases will continue to increase across northern OK and the OK panhandle. The spraying window across much of Oklahoma is now getting quite tight, and a producer needs to be certain to follow the fungicide label regarding when a fungicide can be applied in order to be in compliance with the label. For more information on applying fungicides and their relative effectiveness in managing foliar diseases, see OCES Current Report (CR-7668) that can be found at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-4987/CR-7668w...

Finally, in addition to the rusts, Septoria tritici blotch and powdery mildew, other diseases that have been observed include an occasional loose smutted head as observed by Zack Meyer (Sales Agronomist with CHS) near Hennessey, OK. I also have seen an occasional head of loose smut this year in various fields. It merits to mention that if you see loose smut or common bunt in a field, do not save seed from that field for planting the next year as that will lead to increasing that smut or bunt. If that field is planted again in wheat, be sure to plant seed treat at a high rate with a fungicide effective against the bunts and smuts. Barley yellow dwarf also has been seen in various fields and trials around the state but is much less prevalent than typical as are the mite-transmitted viruses, especially wheat streak mosaic virus.

--Bob Hunger, Extension Plant Pathologist, Oklahoma State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from KS, 05/07/19

Wheat in southeastern and south-central Kansas is at heading stages of development. Wheat in these areas will reach the growth stages critical for Fusarium in roughly week to 3-5 days. The model is indicating moderate or high risk of severe disease just as we head into the most vulnerable period of growth. The risk is likely to persist or increase if these regions continue to receive frequent rainfall and extended periods of high relative humidity. Growers in southeastern and south central Kansas should be monitoring situation carefully and planning to apply a fungicide if weather conditions remain favorable. Care should be taken to select an effective fungicide for management of FHB with Prosaro, Caramba and Miravis Ace being the best options. Many other fungicides are less effective or are not labeled for Fusarium suppression.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from KS, 05/03/19

Wheat in southeastern and south-central Kansas is at heading stages of development. Wheat in these areas will reach the growth stages critical for Fusarium in roughly week to 5-7 days. The model is indicating moderate risk of severe disease just as we head into the most vulnerable period of growth. The risk is likely to persist or increase if these regions continue to receive frequent rainfall and extended periods of high relative humidity. Growers in southeastern and south central Kansas should be monitoring situation carefully and planning to apply a fungicide if weather conditions remain favorable.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from OK, 04/27/19

Reports of rust activity definitely were on the upswing this past week in Oklahoma. At the field day yesterday at Chickasha in central OK, I saw only sparse stripe rust, but I also heard reports that sounded to me as though rust (both stripe and leaf rust) will be making a strong appearance in Oklahoma. Lance Embry (WestBred/Monsanto) indicated he had recently been in central Texas and saw severe stripe and leaf rust, with a slight edge to the stripe rust. Heath Sanders (SW OK Area Extn Agronomy Spclt) indicated that earlier in the week he saw some stripe rust and tan spot in Tillman County (SW OK), but that overall the leaves looked pretty good. This is consistent with what Gary Strickland observed in southwestern OK last week, where he indicated,
“I was in several fields yesterday. Most fields are boot (some are a little later yet) to heading (some fields have just started blooming). I found incidence of both stripe and leaf rust. However, in only 2-3 fields was it heavy enough (combined with a good yield potenetial, 45+ bushels) and had advanced up the plant that I felt like spraying was an immediate need. In most other fields while I would find both species low on the plant or mid-way in the plant but it was typically very low severity. So, in the end both species were present but I think stripe rust was probably more prevalent. But overall, severity is not high for either rust species. I found no powdery mildew. Septoria and a little tan spot were present but the Septoria is still the predominant disease that I am seeing. In nearly all cases it remains low on the plant. In one field it had advanced mid-way up the plant and caused a lot of yellowing of the lower leaf canopy but again that has just been in one case. With high field moisture present and humid canopy conditions existing I am telling producers to keep a close eye on their field because conditions are right for the disease to spread quickly.”

Moving a bit northward in Oklahoma, Lanie Hale (Wheeler Brothers) reported the following while scouting fields north and west of Loyal to Okeene and Hitchcok and then to just east of Canton, OK:
“I found Stripe Rust in two fields and one field with leaf rust. Some of the fields I checked were repeats of 10 days ago where I found no rust. The Septoria and Tan Spot are now on the third leaf down with occasional spots on the second leaf and flag leaf. Aphids infestations are still heavy in some fields and on the heads in one field I looked at. I’ve seen a couple of small Army worms on the beards; something else to watch for with the good moisture and heavy wheat. A good number of heads in most fields show some freeze damage to the top 2-4 kernels, plus some trapped and twisted heads especially on the field edges.”

Note in Lanie’s observations that he also is seeing the leaf spotting diseases tan spot and septoria as well as aphids and some army worms. Regarding the leaf spot diseases and aphids, this is similar to what I saw and have heard from others. The leaf spot diseases typically don’t move up onto the upper leaves in Oklahoma unless we have continued cool and wet weather, which appears to be in the forecast for at least the next week. However, Lanie indicates he has seen some spots up on the flag leaf and the leaf just under the flag. Hence, application of a fungicide in these cases at this point in time will also help in managing the rusts. For more information on applying fungicides and their relative effectiveness in managing foliar diseases, see OCES Current Report (CR-7668) that can be found at:
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-4987/CR-7668w...

Moving still further north and northwest in Oklahoma, Josh Bushong (NW OK Area Extn Agronomy Spclt) reported seeing, “No PM (powdery mildew), LR (leaf rust), or YR (stripe rust) found in Roger Mills (checked all 20 varieties in demo plot) and Blaine counties.”

These reports lead me to believe that leaf spot diseases (septoria and tan spot) are more prevalent than typical for the western half of Oklahoma. Further, the rust (both leaf and stripe) are making their entrance considerably later than typical for Oklahoma, but with continued relatively mild temperature and moisture I would look for all these foliar diseases to increase.

--Bob Hunger, Extension Plant Pathologist, Oklahoma State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

FHB Update from KS, 04/26/19

Wheat in southeastern and south-central Kansas is at flag leaf emergence, and boot. Wheat in these areas will reach the growth stages critical for Fusarium in roughly 10-14 days. We will be monitoring for the risk of disease and provide more updates soon.

--Erick DeWolf, Extension Plant Pathologist, Kansas State University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org

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