2024 Cereal Rust Risk Report (May 20-26, 2024)

The third weekly Prairie wind trajectory cereal rust risk report for 2024 is available for download now at the following link: May 20-26, 2024 report.  

As of the week of May 20-26, 2024, the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows:

Pacific Northwest – There were low numbers of reverse wind trajectories that passed over the PNW region and into the Prairies, while stripe rust development is continuing in the PNW.  Prairie winter wheat crops are progressing into the tillering and stem elongation stages, while much of the spring wheat crop has now been seeded or will be seeded soon.  Overall, as of May 26, 2024, the risk of stripe rust appearance from the PNW is relatively low and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – There was only one reverse wind trajectory that passed over the TX/OK region and into the Prairies from May 20-26, 2024, while stripe and leaf rust development are continuing, although levels appear to be generally low, especially in commercial winter wheat fields in the TX/OK region.  As Texas and Kansas winter wheat crops move towards maturity and harvest, they will no longer represent a source of rust inoculum for the Prairie region.  Prairie winter wheat crops are progressing into the tillering and stem elongation stages, while much of the spring wheat crop has now been seeded or will be soon.  Overall, as of May 26, 2024, the risk of stem, leaf, stripe, and crown rust appearance from the Texas-Oklahoma corridor is relatively low and scouting for these diseases in the Prairie region is not urgent.

 

Kansas-Nebraska corridor – There was a small number of reverse wind trajectories that passed over the KS/NE region and into the Prairies from May 20-26, 2024, while stripe and leaf rust (Kansas) development are continuing in commercial winter wheat fields in this region.  Prairie winter wheat crops are moving into the tillering to stem elongation stages, while much of the spring wheat crop has now been seeded or will be soon.  Overall, as of May 26, 2024, the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is relatively low and scouting for these diseases in the Prairies is not urgent.

The early and widespread appearance of stripe rust in the PNW, TX/OK and KS/NE regions is still concerning, while the recent stripe rust observations from South Dakota and Wisconsin bring the stripe rust issue ever closer to the Prairies, especially the central to eastern region.  Over the next 2-4 weeks if favourable weather conditions (especially more rainfall) occur in these source US regions, further rust development could occur.  This would result in more rust spores being available to be blown into the Prairie region, as well as more northerly rust development into the Dakotas and Minnesota/Wisconsin.  Currently, Prairie winter wheat fields are most at risk, but fortunately most current winter wheat varieties have intermediate to high levels of resistance, although AC Radiant, CDC Buteo, AAC Elevate, Broadview, and CDC Falcon are rated as susceptible (https://www.seed.ab.ca/variety-data/cereals/; https://saskseed.ca/wp-content/uploads/2020/12/2024-Varieties-of-Grain-Crops.pdf; https://www.seedmb.ca/pdf-editions-and-separate-section-pdfs/).  In terms of spring wheat (various classes) and durum the following varieties are either an S or MS: 5700PR, AAC Cameron, AAC Iceberg, AAC Tisdale, AAC Tomkins, AAC Warman, AAC Whitefox, AC Foremost , Cardale, CDC Abound, CDC Adamant, CDC Flare, CDC Pilar, Faller, Prosper, SY Natron, SY Rorke, SY Torach, and Unity.  If you are growing a stripe rust susceptible variety, it will be important to keep an eye on your crops and follow further PCDMN cereal risk updates (https://prairiecropdisease.blogspot.com/).  

Prairie Crop Disease Monitoring Network Quick Disease Reporter Tool (PCDMN QDRT): Please contribute your Prairie field crop disease observations in 2024!

The spring of 2024 started dry in some Prairie regions, but recent rains have resulted in improved moisture conditions for crop establishment and subsequent development.  Most of the Prairies have 30 day rainfall amounts were normal to above normal (Figure 1). Cumulative rainfall has been greatest along the Alberta-Saskatchewan border and across southern regions of Manitoba, Saskatchewan and Alberta. Total rainfall (mm) over the past 30 days was 64 mm and was 233% of climate normal values. So far, rainfall amounts in 2024 are much greater than last year. In 2023, rain for April 20 to May 19 was 48% of normal. This is good news for farmers, but moist conditions can elevate disease risk.  Moisture can increase the risk of seed and seedling disease issues, early season root infections, and facilitate pathogen fruiting body and spore development.  As we move into June this moisture can increase the risk of subsequent canopy disease development, and thus the potential need for fungicide application for foliar disease management in cereals and pulses.  Staying on top of rapidly emerging disease issues such as leaf spots and rusts can be challenging during a very busy growing season.  

Figure 1.  Percent of average precipitation on the Prairies over the past 30 days as of May 22, 2024.

To help facilitate awareness of developing plant disease issues on a regional- and prairie-wide basis, the Prairie Crop Disease Monitoring Network (PCDMN) and the three Prairie provincial pathologists have worked with colleagues from the Agriculture and Agri-Food Canada (AAFC) Geomatics Group since summer 2021.  The result of this collaboration is the development and deployment of the Prairie Crop Disease Monitoring Network Quick Disease Reporter Tool (PCDMN QDRT).  

The PCDMN QDRT can be used to make quick general reports of diseases in common crops over the Prairie region as part of the Prairie Crop Disease Monitoring Network.  These reports will be used to prepare PCDMN QDRT disease update maps.  Initially our target is to provide bi-weekly map updates.  The maps will be shared via the PCDMN Blog and PCDMN Twitter feed as well as via provincial government or producer group crop/disease updates during the summer.  PCDMN QDRT reports will aid in identifying regions where disease outbreaks are starting to occur.  This information provides a timely heads-up for producers and crop consultants indicating where further in-crop scouting and risk assessment are needed, especially when a fungicide application is being considered for foliar disease management.  Please note the success of the PCDMN QDRT is dependent on farmer, consultant/agronomist, researcher and producer group/provincial extension staff participation.  The greater the number of reports, the better able we are to inform individuals and organizations regarding emerging disease issues so they can take appropriate and timely actions.

A tutorial for the installation and use of the PCDMN QDRT can be found here: PCDMN QDRT tutorial (Spring 2023 version).

Please consider installing the PCDMN QDRT app (used in conjunction with the Survey 123 app) on your smartphone and contributing your field crop disease observations as we move into June and July.  The PCDMN respects individual farmer's and consultant's privacy concerns.  All QDRT submissions are made on a municipality basis for each Province without having to provide specific field location information.

Associated with the use of the PCDMN QDRT is the need to take digital photographs of symptoms when scouting crops.  In addition, farmers and crop consultants may share these images with consultants, provincial plant disease specialists, plant pathology researchers, producer group extension coordinators, and industry representatives to request a digital diagnosis.  In July 2023, the PCDMN posted a tutorial on digital diagnosis, which highlighted some of the more common mistakes that can be made when taking pictures of disease symptoms. Included in the PCDMN blog article are tips to improve your plant disease photos, which will help facilitate the ability to digitally diagnose issues during the growing season.  The blog article can be accessed here: Say cheese: digital photos and effective plant health diagnostics! 

2024 Cereal Rust Risk Report (May 14-20, 2024)

The second weekly Prairie wind trajectory cereal rust risk report for 2024 is available for download now at the following link: May 14-20, 2024 report.  

As of the week of May 14-20, 2024, the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows:

Pacific Northwest – There were relatively low numbers of reverse wind trajectories that passed over the PNW region and into the Prairies, while stripe rust development is continuing, although levels are generally low, especially in commercial winter wheat fields in the PNW.  Prairie winter wheat crops are progressing into the tillering stage, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks.  Overall, as of May 20, 2024 the risk of stripe rust appearance from the PNW is limited and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – There were no reverse wind trajectories that passed over the TX/OK region and into the Prairies from May 14-20, 2024, while stripe and leaf rust development are continuing, although levels are generally low, especially in commercial winter wheat fields in the PNW.  Prairie winter wheat crops are progressing into the tillering stage, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks.  Overall, as of May 20, 2024 the risk of stem, leaf, stripe, and crown rust appearance from the Texas-Oklahoma corridor is relatively low and scouting for these diseases in the Prairie region is not urgent.

Kansas-Nebraska corridor – There were no reverse wind trajectories that passed over the KS/NE region and into the Prairies from May 14-20, 2024, while stripe and leaf rust development are continuing, albeit levels are generally low, especially in commercial winter wheat fields in this region.  However, elevated stripe rust levels have been observed in central regions of Kansas.  Prairie winter wheat crops are moving into the tillering stage, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks.  Overall, as of May 20, 2024 the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is relatively low and scouting for these diseases in the Prairies is not urgent.

The early and widespread appearance of stripe rust in the PNW, TX/OK and KS/NE regions is still concerning.  Over the next 2-4 weeks if favourable weather conditions (especially more rainfall) occur in these source US regions, further rust development could occur.  This would result in more rust spores being available to be blown into the Prairie region, as well as more northerly rust development into the Dakotas and Minnesota/Wisconsin.  Currently, Prairie winter wheat fields are most at risk, but fortunately most current winter wheat varieties have intermediate to high levels of resistance, although AC Radiant, CDC Buteo, AAC Elevate, Broadview, and CDC Falcon are rated as susceptible (https://www.seed.ab.ca/variety-data/cereals/; https://saskseed.ca/wp-content/uploads/2020/12/2024-Varieties-of-Grain-Crops.pdf; https://www.seedmb.ca/pdf-editions-and-separate-section-pdfs/).  If you are growing a stripe rust susceptible variety, it will be important to keep an eye on your crops and follow further PCDMN cereal risk updates (https://prairiecropdisease.blogspot.com/). 

 

2024 Cereal Rust Risk Report (May 7-13, 2024)

The first weekly Prairie wind trajectory cereal rust risk report for 2024 is available for download now at the following link: May 7-13, 2024 report.  

As of the week of May 7-13, 2024, the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows:

Pacific Northwest – There were low to moderate numbers of reverse wind trajectories that passed over the PNW region and into the prairies, while stripe rust development is continuing, although levels are generally low, especially in commercial winter wheat fields in the PNW.  Prairie winter wheat crops have resumed growth, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks.  Overall as of May 13, 2024 the risk of stripe rust appearance from the PNW is limited and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – There were relatively low numbers of reverse wind trajectories that passed over the TX/OK region and into the prairies, while stripe and leaf rust development are continuing, although levels are generally low, especially in commercial winter wheat fields in this region.  Prairie winter wheat crops have resumed growth, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks. Overall as of May 13, 2024 the risk of stem, leaf, stripe, and crown rust appearance from the Texas-Oklahoma corridor is limited and scouting for these diseases in the Prairie region is not urgent.

Kansas-Nebraska corridor – There were relatively low numbers of reverse wind trajectories that passed over the KS/NE region and into the prairies, while stripe and leaf rust development are continuing, although levels are generally low, especially in commercial winter wheat fields in this region.  Prairie winter wheat crops have resumed growth, while much of the spring wheat crop has just been seeded or will be seeded over the next two weeks.  Overall as of May 13, 2024 the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is limited and scouting for these diseases in the Prairies is not urgent.

The early and wide spread appearance of stripe rust in the PNW, TX/OK and KS/NE regions is concerning.  Over the next 2-4 weeks, if favourable weather conditions (especially more rainfall) occur in these source US regions, further stripe and leaf rust development could occur.  This would result in more rust spores being available to be blown into the Prairie region, as well as more northerly rust development into the Dakotas and Minnesota/Wisconsin.  Currently, Prairie winter wheat fields that have started to regrow are most at risk, but fortunately most current winter wheat varieties have intermediate to high levels of resistance, although AC Radiant, CDC Buteo, AAC Elevate, Broadview, and CDC Falcon are rated as susceptible (https://www.seed.ab.ca/variety-data/cereals/; https://saskseed.ca/wp-content/uploads/2020/12/2024-Varieties-of-Grain-Crops.pdf; https://www.seedmb.ca/pdf-editions-and-separate-section-pdfs/).  If you are growing a stripe rust susceptible variety, it is important to keep an eye on your fields and follow further PCDMN cereal risk updates (https://prairiecropdisease.blogspot.com/). 

Update on the USA cereal rust situation and potential implications for Prairie cereal producers

T.K. Turkington, R. Aboukhaddour, and B. McCallum.

Previous PCDMN blog posts have highlighted potential emerging stripe rust issues in the USA; unfortunately, this may mean stripe rust issues for Prairie wheat growers. The most recent reports from Dr. Chen, USDA-ARS and Washington State University (WSU), indicated continued development of stripe rust in research plots and commercial fields (https://smallgrains.wsu.edu/stripe-rust-24/, https://striperust.wsu.edu/2024/04/28/stripe-rust-update-april-26-2024/).  Incidence levels in commercial fields were generally low, although Dr. Chen did observe a hot spot of elevated severity in a commercial field.  Dr. Chen cautions that forecast cool weather and rainfall could promote further development of stripe rust.  As mentioned previously  Dr. C. Hagerty of the Columbia Basin Agricultural Research Centre (CBARC), Oregon State University also reported stripe rust on susceptible lines at the CBARC, Pendleton, OR and encouraged growers to scout and consider fungicide application (https://osu-wams-blogs-uploads.s3.amazonaws.com/blogs.dir/2823/files/2024/04/2024_April_Rust.pdf).  Recent X (formerly Twitter) posts from Dr. D. Larkin, wheat Breeder Limagrain, April 18, 2024, (https://twitter.com/dylarkin/status/1781102306593050890)

 

Reports continue regarding stripe rust in Texas, Oklahoma and Kansas, and these early observations suggest these regions may experience severe stripe rust epidemics if conducive weather occurs over the next several weeks.  Maps from Kansas State University and AG PEST Monitor: Wheat, indicate stripe rust development in numerous counties in Oklahoma and Kansas (Figures 1 and 2, https://wheat.agpestmonitor.org/stripe-rust/, https://eupdate.agronomy.ksu.edu/article_new/stripe-rust-distribution-and-risk-assessment-for-kansas-april-25-2024-589-5).  As mentioned in the PCDMN blog post from April 19, 2024, Drs. S. Liu, B. Gerrish, and J. Rudd, Texas A&M University reported stripe rust, as well as leaf and stem rust of wheat, and crown and stem rust of oat in Texas (https://varietytesting.tamu.edu/wp-content/uploads/sites/17/2024-Wheat-Rust-Report.pdf).  Earlier in April, Dr. M. Aoun, OSU reported that stripe rust potentials were high in Oklahoma and timely scouting by farmers was encouraged (https://spotlight.okstate.edu/wheat-pathology/2024/04/02/wheat-disease-update-2-april-2024/, https://www.farms.com/videos/crops/scout-for-stripe-rust-209386.aspx).  Most recently, Dr. M. Aoun reported increased levels of stripe rust on winter wheat at Stillwater and Chickasha, OK, while leaf rust was also noted (https://twitter.com/OSUwheatdisease/status/1784421264242720939).  In an article by L. Vihauer, High Plains Journal, Dr. M. Aoun indicates significant development of stripe rust in SE Oklahoma, although conditions are dry and rain is needed, which will increase stripe rust risk (https://hpj.com/2024/04/19/stripe-rust-a-concern-in-oklahoma-wheat/).  On April 29, 2024, Dr. B. Carver, Oklahoma State Wheat Improvement Team also mentioned continued development of leaf rust on winter wheat in central regions of Oklahoma (https://twitter.com/osuwit/status/1785003699426689353).  

In western Canada, early development of stripe rust in disease nurseries at Abbotsford and Creston, BC have been reported by Dr. G. Brar, U of Alberta, formerly of UBC, and likely reflect overwintering on winter wheat breeding lines (https://x.com/gurcharn_brar/status/1779910374051209644).  

Overall, US rust risk forecasts and the early widespread occurrence symptoms suggest the PNW and the Texas to Kansas corridor may be important sources of stripe rust inoculum for Prairie wheat growers in 2024.  Currently, Prairie winter wheat crops resuming growth are most at risk.  Fortunately, most winter wheat varieties have intermediate to high levels of resistance, although Radiant, CDC Buteo, AAC Elevate, Broadview, and CDC Falcon are rated as susceptible (https://www.seed.ab.ca/variety-data/cereals/; https://saskseed.ca/wp-content/uploads/2020/12/2024-Varieties-of-Grain-Crops.pdf; https://www.seedmb.ca/pdf-editions-and-separate-section-pdfs/).  

The Prairie Crop Disease Monitoring Network (PCDMN) will be starting their weekly Prairie rust risk forecasts shortly, and these can be found at https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html.  Key management strategies for cereal rusts include host resistance, scouting and awareness of emerging rust issues, and timely fungicide application.  Previous PCDMN Twitter (X) and Blog posts provide additional background information on potential yield losses due to stripe rust as well as the importance of monitoring crops for cereal leaf diseases: 

https://twitter.com/pcdmn/status/1306577312465522690;

https://twitter.com/pcdmn/status/1280178253295169537;

https://prairiecropdisease.blogspot.com/2022/06/scouting-and-risk-assessment.html;

https://prairiecropdisease.blogspot.com/2023/07/end-of-season-assessment-of-cereal-leaf.html

https://twitter.com/pcdmn/status/1347656233243828224

 

Figure 1.  USA stripe rust observations, April 25, 2024, courtesy of AG PEST MONITOR: Wheat, https://wheat.agpestmonitor.org/stripe-rust/.

Figure 2.  Stripe rust occurrence, Kansas, April 25, 2024, Agronomy eUpdates.  Courtesy of Dr. K. Onofre, Extension Plant Pathologist, Department of Agronomy, Kansas State University, https://eupdate.agronomy.ksu.edu/article_new/stripe-rust-distribution-and-risk-assessment-for-kansas-april-25-2024-589-5. 

Continuing signs of stripe rust in the USA may foreshadow a risk for Prairie wheat growers in 2024

T.K. Turkington, AAFC Lacombe, R. Aboukhaddour, AAFC Lethbridge, and B. McCallum, AAFC Morden.

Three previous PCDMN blog posts have highlighted potential emerging stripe rust issues in the USA; unfortunately this may mean stripe rust issues for Prairie wheat growers. As mentioned previously stripe rust risk forecasts from Dr. Chen, USDA-ARS and Washington State University (WSU), indicated the risk of stripe rust for 2024 for the eastern PNW is severe and susceptible winter wheat varieties will potentially incur yield losses (https://www.wawg.org/stripe-rust-report-warmer-november-december-dont-bode-well-for-susceptible-varieties/; https://smallgrains.wsu.edu/first-stripe-rust-forecast-of-the-2024-season/; https://www.wawg.org/march-1-stripe-rust-forecast-calling-for-epidemic-levels-for-eastern-washington/).  In addition, Dr. Chen has reported stripe rust symptoms in research and disease monitoring trials in Washington State including eastern regions, as well as in NE Oregon (Umatilla County).  Both Drs. Chen and Murray, WSU, indicated that not since February 2011 have symptoms of stripe rust been observed this early (https://smallgrains.wsu.edu/stripe-rust-324/; Stripe rust report 4/13: Stripe rust widely occurring in the PNW | WAWG; https://smallgrains.wsu.edu/stripe-rust-24/; https://twitter.com/WSUWheatDoc/status/1781009581860352487).  Dr. C. Hagerty the Columbia Basin Agricultural Research Centre (CBARC), Oregon State University also reported stripe rust on susceptible lines at the CBARC, Pendleton, OR and encouraged growers to scout and consider fungicide application (https://osu-wams-blogs-uploads.s3.amazonaws.com/blogs.dir/2823/files/2024/04/2024_April_Rust.pdf).  Recent X (formerly Twitter) posts from Dr. D. Larkin, wheat Breeder Limagrain, April 18, 2024, (https://twitter.com/dylarkin/status/1781102306593050890)   Overall, rust risk forecasts for the PNW and the early occurrence of significant symptoms suggest the PNW may be an important source of stripe rust inoculum for Prairie wheat growers in 2024.  

As mentioned previously in PCDMN blog posts, stripe rust is also being observed in other areas of the USA including the Texas to Kansas corridor.  There have been multiple reports of stripe rust in Texas and other southcentral States and these early observations suggest that these areas of the US may experience severe stripe rust epidemics if conducive weather occurs (S. Baker, Stripe rust at Chillicothe, TX, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, February 26, 2024; https://twitter.com/J_SBaker/status/1752818506674929882; Dr. O. Fajolu USDA, St. Paul, MN, Cereal Rust Bulletin #1, April 15, 2024, https://www.ars.usda.gov/ARSUserFiles/50620500/CRBs/2024%20CRB%20April%2015.pdf).  Stripe rust is now being reported in Oklahoma and Kansas in a number of areas in March and April (OSU Wheat Pathology, https://twitter.com/OSUwheatdisease/status/1774552781137035533, https://twitter.com/OSUwheatdisease/status/1770869304529199247, https://twitter.com/OSUwheatdisease/status/1776637764496412894; A. Hixson, BASF, https://twitter.com/hixsona/status/1778224217810522353; J. Coltrain, Syngenta, https://twitter.com/josh_coltrain/status/1776240076290216134, https://twitter.com/josh_coltrain/status/1780357856912363741 and https://twitter.com/josh_coltrain/status/1780330445550301428; R. French, French Agronomics, https://twitter.com/frenchrw/status/1779939164655657407; J. Kohls, Wheat Breeder Syngenta, https://twitter.com/jkohls1/status/1779939113589686423; KSU Wheat Pathology, https://twitter.com/KSUWheatDisease/status/1778171057674797477; J. Seiler, KSU, https://twitter.com/SGAgAgent/status/1777742988510187728).    

Dr. M. Aoun, OSU recently reported that stripe rust potentials are high in Oklahoma and timely scouting by farmers is encouraged (https://spotlight.okstate.edu/wheat-pathology/2024/04/02/wheat-disease-update-2-april-2024/, https://www.farms.com/videos/crops/scout-for-stripe-rust-209386.aspx).  Drs. S. Liu, B. Gerrish, and J. Rudd, Texas A&M University, April 2024, have mainly reported stripe rust, but also leaf and stem rust of wheat, and crown and stem rust of oat in Texas (https://varietytesting.tamu.edu/wp-content/uploads/sites/17/2024-Wheat-Rust-Report.pdf).   

In western Canada, early development of stripe rust in disease nurseries at Abbotsford and Creston, BC have been reported by Dr. G. Brar, U of Alberta, formerly of UBC, and likely reflect overwintering on winter wheat breeding lines (https://x.com/gurcharn_brar/status/1779910374051209644).  

You can keep up-to-date with Prairie cereal rust risk via PCDMN cereal rust risk forecasts that are posted to this blog from mid-May to early July each year and can be found at https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html.   Key management strategies for cereal rusts include host resistance, scouting and awareness of emerging rust issues, and timely fungicide application.  It is advised that Prairie producers check the stripe rust resistance rating of the winter and spring wheat varieties they are or will be growing.  Timely scouting and consideration of fungicide use are advised for the 2024 growing season, especially for varieties that are susceptible to moderately susceptible to stripe rust.  As of April 19, 2024, winter wheat fields that have started to regrow are most at risk, fortunately most current winter wheat varieties have intermediate to high levels of resistance, although Radiant, CDC Buteo, AAC Elevate, Broadview, and CDC Falcon are rated as susceptible (https://www.seed.ab.ca/variety-data/cereals/; https://saskseed.ca/wp-content/uploads/2020/12/2024-Varieties-of-Grain-Crops.pdf; https://www.seedmb.ca/pdf-editions-and-separate-section-pdfs/).

Continuing development of stripe rust in the USA may foreshadow a risk for Prairie wheat growers in 2024

Previous PCDMN blog posts have highlighted potential emerging stripe rust issues in the USA; unfortunately this may mean stripe rust issues for Prairie wheat growers.  Stripe rust risk forecasts from Dr. Chen, USDA-ARS and Washington State University (WSU), indicated the risk of stripe rust for 2024 for the eastern PNW is severe and susceptible winter wheat varieties will potentially incur yield losses (https://www.wawg.org/stripe-rust-report-warmer-november-december-dont-bode-well-for-susceptible-varieties/; https://smallgrains.wsu.edu/first-stripe-rust-forecast-of-the-2024-season/; https://www.wawg.org/march-1-stripe-rust-forecast-calling-for-epidemic-levels-for-eastern-washington/).  In addition, Dr. Chen reported stripe rust symptoms, indicating overwintering of stripe rust on winter wheat in the Pacific Northwest (PNW).  On March 19, 2024, Dr. T. Murrary, WSU, referred to Dr. Chen's forecasts and emphasized a potential stripe rust issue for the PNW in 2024, while indicating that not since February 2011 have symptoms of stripe rust been observed this early (https://smallgrains.wsu.edu/stripe-rust-324/).  Overall, rust risk forecasts for the PNW and the early occurrence of symptoms suggest the PNW may be an important source of stripe rust inoculum for Prairie wheat growers in 2024.  

In addition to the occurrence of symptoms in the PNW, there have also been multiple early reports of stripe rust on winter wheat in Texas and Oklahoma in late February and continuing into late March ( (S. Baker, Stripe rust at Chillicothe, TX, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, February 26, 2024; https://twitter.com/J_SBaker/status/1752818506674929882).  Most recently Dr. M. Aoun, Oklahoma State University (OSU) wheat pathology program, reported that stripe rust is developing in Jackson and Tillman Counties in SW Oklahoma (https://spotlight.okstate.edu/wheat-pathology/2024/04/02/wheat-disease-update-2-april-2024/; https://twitter.com/OSUwheatdisease/status/1775200213545959453; https://twitter.com/osuwit/status/1774638870660804917; https://twitter.com/OSUwheatdisease/status/1772315284025593930; https://twitter.com/OSUwheatdisease/status/1770869304529199247).  Interestingly, Dr. B. Carver, OSU wheat breeder, indicated that not since the "early 2000s" have there been such early observations of increased levels of stripe rust.  Dr. M. Aoun also observed stripe rust symptoms in research plots in Payne County, and suggested that forecast cooler wetter conditions could promote further stripe rust development in Oklahoma.  

Although no stripe rust in Kansas has been reported, Drs. K. A. Onofre and E. De Wolf, Kansas State University, recently indicated that observations from Texas starting in late January 2024 and favourable weather conditions suggest stripe rust may be an issue in 2024 (https://eupdate.agronomy.ksu.edu/article_new/outlook-for-stripe-rust-in-2024-kansas-wheat-crop-584-3).  They emphasized the value of monitoring winter wheat for stripe rust symptoms as further crop development occurs.  Further development of stripe rust in the Texas to Nebraska corridor over the next 1-2 months could pose a risk for Prairie wheat growers, especially in central to eastern regions.  

Stay tuned for our regular weekly PCDMN rust risk forecasts starting in mid-May (https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html), while further updates on the US rust situation will be posted on the PCDMN blog.  

2nd stripe rust forecast for the eastern Pacific Northwest - Dr. X. Chen, March 1, 2024 : An updated heads up for Prairie cereal producers for 2024

This is an update to a PCDMN post on January 9, 2024.  Updated information from the Pacific Northwest (PNW) of the US provides a further head's up regarding potential Prairie stripe rust risk in 2024.  In his March 1, 2024 update, Dr. X. Chen, with USDA-ARS and Washington State University, indicates the risk of stripe rust for 2024 for the eastern PNW is severe and susceptible winter wheat varieties will potentially incur yield losses in the 40-60% range if they are not sprayed with fungicide.  The projected yield loss for highly susceptible varieties has increased from 42% with the January 2024 update (https://www.wawg.org/stripe-rust-report-warmer-november-december-dont-bode-well-for-susceptible-varieties/; https://smallgrains.wsu.edu/first-stripe-rust-forecast-of-the-2024-season/) to 51% for the March 1, 2024 update (https://www.wawg.org/march-1-stripe-rust-forecast-calling-for-epidemic-levels-for-eastern-washington/).  Fortunately, varieties with moderate to high levels of resistance will mitigate stripe rust risk and the need for fungicide.  However, virulence shifts can occur so keep this in mind if you start to see more stripe rust than expected in any resistant varieties you are growing on the Prairies.  Dr. Chen also indicated in his March 1, 2024 update that stripe rust appears to have successfully survived the winter on infected winter wheat crops, with multiple reports of symptoms in recently checked rust monitoring nurseries and commercial fields.  Moreover, these 2024 observations in Washington State, especially east of the Cascade mountains, are earlier compared to 2011 to 2023.  Overall, the PNW may have levels of stripe rust in 2024 that could threaten Prairie winter and spring wheat crops.  

Unfortunately, Dr. Chen also indicated in his March 1, 2024 update that there have been multiple reports of stripe rust in Texas and other southcentral States and these early observations suggest that these areas of the US may experience severe stripe rust epidemics if conducive weather occurs.  Observations of stripe rust in Texas by Texas A&M staff were recently posted by S. Baker, Texas A&M AgriLife Research, based on observations by J. Baker and D. Hathcoat (S. Baker, Stripe rust at Chillicothe, TX, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, February 26, 2024; https://twitter.com/J_SBaker/status/1752818506674929882)

Each year the PCDMN issues weekly cereal rust risk forecasts based on rust development in source locations in the USA.  The PNW is mainly a concern in terms of stripe rust, while the Texas to Nebraska corridor represents a risk for leaf rust, stripe rust and stem rust, while there may be concerns related to crown rust in oat.  In addition to accounting for rust development in the US, the PCDMN also looks at the number of wind trajectories that may carry rust spores from US source locations, and Prairie crop development and weather conditions. 

You can keep up-to-date with Prairie cereal rust risk via PCDMN cereal rust risk forecasts that are posted to this blog from mid-May to early July each year and can be found at https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html. 

Key management strategies for cereal rusts include host resistance, scouting and awareness of emerging rust issues, and timely fungicide application.  It is advised that Prairie producers check the stripe rust resistance rating of the winter and spring wheat varieties they are or will be growing.  Timely scouting and consideration of fungicide use are advised for the 2024 growing season, especially for varieties that are susceptible to moderately susceptible to stripe rust.

The PCDMN will follow up with further risk reports from Dr. Chen as we move towards the 2024 Prairie growing season.

Typical symptoms of stripe rust are as follows: 

Stripe rust forecast for the eastern Pacific Northwest - Dr. X. Chen: A heads up for Prairie cereal producers for 2024

We are still a few months away from the 2024 Prairie growing season.  However, information from the Pacific Northwest (PNW) of the US does give a head's up regarding potential Prairie stripe rust risk in 2024 (https://www.wawg.org/stripe-rust-report-warmer-november-december-dont-bode-well-for-susceptible-varieties/).  Dr. X. Chen with USDA-ARS and Washington State University issues stripe rust forecasts for the PNW region based on weather conditions in November and December.  Unfortunately, Dr. Chen's update for January 8, 2024 indicates the risk of stripe rust for 2024 for the eastern PNW is severe and susceptible winter wheat varieties will incur average yield losses of 42% if they are not sprayed with fungicide.  Fortunately, varieties with moderate to high levels of resistance will mitigate stripe rust risk and the need for fungicide.  However, virulence shifts can occur so keep this in mind if you start to see more stripe rust than expected in the resistant variety you are growing.  Overall, the PNW may have issues with stripe rust that could threaten Prairie winter and spring wheat crops.  

Each year the PCDMN issues weekly cereal rust risk forecasts based on rust development in source locations in the USA.  The PNW is mainly a concern in terms of stripe rust, while the Texas to Nebraska corridor represents a risk for leaf rust, stripe rust and stem rust, while there may be concerns related to crown rust in oat.  In addition to accounting for rust development in the US, the PCDMN also looks at the number of wind trajectories that may carry rust spores from US source locations, and Prairie crop development and weather conditions. 

You can keep up-to-date with Prairie cereal rust risk via PCDMN cereal rust risk forecasts that are posted to this blog from mid-May to early July each year and can be found at https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html. 

Key management strategies for cereal rusts include host resistance, scouting and awareness of emerging rust issues, and timely fungicide application.  

The PCDMN will follow up with further risk reports from Dr. Chen as we move towards the 2024 Prairie growing season.

Typical symptoms of stripe rust are as follows: 

End-of-season assessment of sclerotinia stem rot of canola (PCDMN)

The spring and summer of 2023 was challenging for Prairie producers who experienced very dry conditions, especially under dryland production.  Although this limited disease issues, the drought stress had a very significant negative impact on stand establishment, crop growth, and yield.  However, some Prairie regions did receive moisture during the course of the summer and in these regions field crop diseases may be more of a concern.

We are at or fast approaching the time when you can rate sclerotinia stem rot in your canola. Ideally, plants should be rated within a week or so before the crop would normally be swathed (if it was being swathed of course). Once the crop starts to turn, rating becomes very difficult. 

Key characteristics of sclerotinia infections in canola include:

• Infected tissue has a characteristic bleached white/whitish/tan gray appearance
• Affected tissue when it dries is very brittle and shreds and shatters easily when you twist the stems
• The pith portion of affected stems is typically not present
• In heavily infected stems the pith tissue is destroyed leaving only the outer ring of stem tissue
• Sclerotia (black resting bodies) or sclerotial initials (clumps of compacted white hyphae that turn black when mature) are typically produced in or on affected plant tissues 
• External sclerotia typically develop when you have wet conditions following infection and as the crop progresses towards senescence.

Symptoms not characteristic of sclerotinia: 

• Infected tissue doesn’t have a bleached white/whitish grey or tan appearance 
• Affected tissue is not brittle and doesn’t shred and shatter when you twist the stems between your hands 
• The pith portion of stems is still intact
• Sclerotia or sclerotial initials (dense clumps of white hyphae) are not produced in/on suspect symptoms
• Yellowing of stems/branches may be due to other factors, such as root disease, nutrient, or weather stress, etc.

For sclerotinia one can look at the incidence of infection, and focus on the main stems and branches. Infections on the main stem and/or branches have the largest impact on yield. However, if incidence is low (<5%), the impact on yield is negligible.  

In most canola fields, plants will typically lean in a particular direction.  Use this to your advantage and work with the flow of plants.

When assessing stem rot levels, one should look at a representative sample of plants throughout the field. For example, a minimum of 4-6 sites should be looked at in a quarter section field; then at each site between 50-100 plants should be assessed.  

Half or full section fields will require more sites.  If the field is quite variable then separate assessments in specific areas may be needed, e.g. lodged versus non-lodged. 

Assessments can also be made in sprayed versus check areas to determine the usefulness and benefit of in-crop fungicide applications.  Unsprayed checks, even small areas, can be quite useful.

An alternative rating scale is one from Kutcher and Wolf (2006).  Although a bit more complicated, it covers infections on various parts of the plant.  Note symptoms in the upper canopy (pods, etc.) generally have less impact on yield.

 

Rules of thumb have been developed to assess the potential loss associated with stem rot infections.  In general the % yield loss is approximately 0.5 times the % of infected plants (main stem or main branch infections).  Thus, if you note 30% infected plants, the potential yield loss is approximately 15%.  

The PCDMN has also produced overviews for assessment of stem rot levels and identification of disease symptoms accessible with the following hyperlinks: 

• An assessment protocol for sclerotinia stem rot in canola 

• A slide deck overview of a guide to scouting and identification of sclerotinia stem rot in canola 

• Playing cards describing sclerotinia stem rot of canola symptoms