Central Great Plains HWW Region's blog

FHB Update from OK, 05/31/18

Wednesday through Friday (May 23-25) of last week, I was in western Oklahoma (Clinton area) and at field days in the panhandle at Goodwell and Hooker (Texas County), Keyes (Cimarron County) and Balko (Beaver County). The only disease observed of significance was indicated by white heads in fields. Often this was the result of Fusarium (dryland) root rot as reported in the last update (May 17, 2018). In fields showing this root rot, the white heads and white tillers were scattered across the field with an incidence ranging from low to moderate. Other fields in the panhandle exhibited large areas of not just white heads and tillers, but also white secondary tillers that had not headed. In these fields, some root rot was found but Dr. David Marburger (OkSU Small Grains Extension Specialist) and I believe that many of the white tillers/secondary tillers were the result of drought, freeze, or a combination of both. Often such tillers showed clean lower stems with no indication of root rot. We believe these secondary tillers were completely white without heading because they were sloughed off as a result of the stress from drought, freeze, or a combination of both. We suspect that more of these whiteheads will show in the coming week in northwestern OK and the panhandle, but the wheat crop is quickly turning and the whiteheads may not be as evident.

This likely is the last update I will be sending out this season as harvest in the southern half of Oklahoma has started with the crop quickly maturing in the northern half.

--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, 05/25/18

Wheat in most areas of Kansas is now past the flowering stages of growth that are most vulnerable for Fusarium infection. There may be some late planted fields in the north central and northwestern regions that are still flowering. Dry conditions appear to have most of the state at low risk. There is an area of high risk in southeast KS showing on the risk map today. This area has received more rain than most areas of the state, however, the wheat in these counties is already in the dough stages of development that are less vulnerable to infection.

Elsewhere in the central great plains, it appears that parts of Nebraska may be at risk for infection. Growers in this area should consult with local extension for advice on the need for fungicide applications.

--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, 05/17/18

Although not as obvious as in previous weeks, powdery mildew is still hanging on in Oklahoma, and has even moved up onto the heads in some fields. One such field is my foliar fungicide trial here at Stillwater. Examining this trial yesterday revealed many of the lower heads were lightly to moderately infected with powdery mildew. This is one of the few times I have seen powdery mildew move onto wheat heads in Oklahoma. It is important to note that these infected heads are the ones produced on the lower tillers beneath the main, taller tillers. I did not find any powdery mildew on any of the higher heads. This appears to me to be a light to moderate infection severity, but I’ve not had a lot of experience with powdery mildew on wheat heads, so this is just my estimation. Exactly how much of an impact this powdery mildew will have on yield and test weight may be hard to determine because the level of powdery mildew on these heads seemed to be fairly constant across all treatments.

Yesterday, I also observed leaf rust on scattered leaves in the foliar fungicide trial at Stillwater (mostly in the not-sprayed control plots). Typically this was just a couple pustules scattered on a leaf. This indicates that leaf rust is starting to appear and may increase a bit over the next 7-10 days. However, this is a late infection as this trial is at late milk to early soft dough. Hence, the leaf rust will have only a minimal impact on yield even if it does increase significantly.

Finally, Brad Babek (County Educator, Washita County in southwestern Oklahoma) reported increasing areas of white heads in wheat fields. In cases where I have observed such heads this year, it has been due to dryland (Fusarium) root rot. Typically the roots will be rotted and often the lowest part of the stem is discolored (dark) and often there is a pinkish-purple color associated with the lower tiller and roots. Splitting such a tiller often reveals a stem filled with white or pinkish-white fungal growth.

--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, 05/08/18

Wheat in southeast Kansas is currently at the heading and flowering stages of growth that are most vulnerable to infection by the Fusarium fungus. The risk maps currently indicate the risk of severe head blight, but given recent rains and humidity, I believe the risk may be greater than predicted. Wheat growers in Southeast portion of the state should consider protecting their crop with a fungicide. Prosaro, and Caramba are the best available fungicide options for FHB management. Folicur or generic tebuconazole fungicides would also be an option. Fungicides containing strobilurin active ingredients are not labeled for control of Fusarium head blight and should be avoided.

--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, 05/05/18

This past week I was at field days in southwestern Oklahoma (Apache and Altus), and northeastern Oklahoma (Afton). I didn’t see a single leaf or stripe rust pustule at any location. Wheat in southwestern OK ranged from at flowering to kernel formation, and typically was short (less than knee high). There were a few exceptions to this, namely a couple fields near Apache that had been planted on summer fallow ground. Wheat in these two fields looked good with some powdery mildew on the low to mid-canopy. There also was evidence of root rot (white heads) that was caused by Fusarium (Figure 1). This root rot was at a low incidence. By contrast, wheat in northeastern OK was at flowering and typically was over knee-high, thick, and with high yield potential. On many varieties, powdery mildew was heavy in the low and mid-canopy, and in a few instances also was present on the flag leaf (Figure 2). Besides powdery mildew, Septoria leaf blotch was heavy throughout the lower leaves of most varieties. In northeastern OK it appears that if a fungicide is going to be sprayed, that needs to be applied as soon as possible.

Based on my observations this past week and the recent report from Texas, it appears that rust pressure is low across Texas and Oklahoma. Hence, although there still is time for the rusts (especially leaf rust) to impact Oklahoma, it does not appear there will be an early season (during heading) high rust pressure as in most years. I still would be watchful and if you have a variety known to be susceptible to leaf rust with good yield potential (>about 30 bu/acre) I recommend considering a fungicide application. Be sure however, that your wheat has not matured past the allowed time (as indicated on the label) for the fungicide you apply. Additional information related to foliar fungicides can be found on the fungicide label and in OSU Current Reports 7668, Foliar Fungicides and Wheat Production in Oklahoma, which is available at: http://dasnr22.dasnr.okstate.edu/docushare/dsweb/Get/Document-4987/CR-76....

--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, 04/26/18

Although reports of powdery mildew continue to come in from around the state, perhaps the more important news is that other foliar diseases have started to become active. On Apr-24, Septoria tritici blotch (Figure 1) was prevalent on lower leaves throughout the variety trial near Walters, OK. Walters is located in southwestern Oklahoma about 20 miles south of Lawton & 10 miles north of the Texas border. Although interesting, Septoria tritici blotch is not the disease of concern as in this trial there also was active leaf rust on lower leaves (Figure 2) and stripe rust on the leaves just below the flag leaf. Dr. Brett Carver (OSU Professor/Wheat Breeder) and Branden Watson (OSU PaSS Graduate Student) also reported active stripe rust at various levels in trials located near Chickasha, OK in central Oklahoma (Figure 3). The photo from Dr. Carver (the right photo in Figure 3) shows much more severe stripe rust than was seen near Walters. These observations indicate that both stripe and leaf rust are increasing through southern and central Oklahoma. This activity will increase through the coming weeks as the forecast indicates continued moisture (rains and dew) coupled with moderate temperature. Wheat in southern Oklahoma was approaching or was actively flowering, so the option of using a fungicide to protect yield potential either is at hand or may be too late. Most fungicides labeled for wheat rust control must be applied by the start of flowering (Feekes’ growth stage 10.5). The only fungicides I know of that have a label allowing for a later application are Tilt, Quilt Xcel, and Trivapro, which can be applied up to Feekes’ 10.5.4 (end of flowering with the kernel watery ripe). In addition to these application deadlines, there often are required pre-harvest intervals so you must allow for a specific number of days to elapse between application of the fungicide and harvest. For specific information, please consult the label for the fungicide.

--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, 04/25/18

Wheat in southeast Kansas will likely reach the heading and flowering stages of growth that are most vulnerable to infection by the Fusarium fungus over the next 7 to 10 days. The risk maps currently indicate the risk of severe head blight is low because of dry conditions in early April. The risk of disease may increase rapidly over the next week as rain moves through the area.

--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, 04/13/18

Wheat in central Oklahoma was reported at growth stages 8-9 (flag leaf emerging to flag leaf fully emerged). In northern Oklahoma, wheat was extremely variable with growth stages from 2-8 (tillering to flag leaf emerging) being reported. Powdery mildew continued to be the primary wheat foliar disease this past week in Oklahoma. Around Stillwater, I have seen powdery mildew on the lower and mid-leaves with severities reaching 90% on the lower leaves. A preponderance of powdery mildew on lower to mid leaves also was indicated across Oklahoma by reporting from Extension Educators. There was one report of stripe rust in south central Oklahoma from near Ardmore, OK. This report indicated both active stripe rust and the dormant (telial) spore stage of stripe rust. The only other observation this week has been “spots” of barley yellow dwarf as reported last week. However, after the recent freeze events, these barley yellow dwarf “spots” are more difficult to discern because there is widespread burning of leaf tips from the freeze, which has a masking effect.

--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, 05/25/17

The wheat in southeast and south central Kansas is at the late milk and dough stages of kernel development. The symptoms of Fusarium head blight (head scab) are most evident at these growth stages and it is important for growers to be out looking for disease this week. Symptoms will soon be masked by natural maturity of the crop.

--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, 05/06/17

Wheat in the central portion of Kansas is now at flowering stages of growth that are most vulnerable to Fusarium head blight. The risk models currently indicate a low to moderate risk of disease for most of this area. The weather forecast indicates we are about to enter a period with higher temps and multiple days without rain. This should keep the risk of severe disease in central Kansas low for much of this critical period.

--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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