Prairie soil moisture maps: June 26, 2023

Prairie soil moisture levels and need to scout for apothecia of the sclerotinia stem rot pathogen, June 26, 2023

 As June 26, 2023 most Prairie regions have well below normal soil moisture with large areas with <40 to 60% of normal levels (Figures 1-3).  However, some areas including the Edmonton region have 85-115% of normal soil moisture levels (Figure 1).  Based on satellite data from June 19-25, 2023, large areas of the Prairies are still dealing with dry conditions and would only have <5 to 20% surface soil moisture (VMC) (Figure 2).  However, some regions are seeing soil moisture levels increasing due to recent rains including the Edmonton region, and some smaller regions in the northern cropping areas in Saskatchewan and Manitoba (Figure 2).  Corresponding, satellite images for June 19-25 show well below long term average soil moisture levels for large areas of the Prairies including regions where sclerotinia stem rot can occur (Figure 3). However, as a result of rainfall over the last few weeks, areas including the Edmonton region and south towards Red Deer are closer to normal or above normal.   

As of June 26, the need to scout fields for apothecia of the stem rot fungus and/or to assess in-field risk is low.  This is based primarily on soil moisture maps as canola crops have or will shortly start flowering (Figures 1-3).  However, recent rainfall over some Prairie regions will likely trigger the start and continuation of the sclerotial germination process, which can take up to three weeks.  Further rainfall and crop canopy closure may increase the risk of sclerotial germination and apothecia production.  Areas in the Edmonton region and south to Red Deer likely have soil moisture conditions conducive for sclerotial germination.  In these areas in-crop scouting for apothecia and the use of available stem rot risk assessment tools may be needed over the next 1-3 weeks as part of fungicide use decisions (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment). 

Background information on the soil moisture maps can be found at the following link: New for 2023: Prairie Soil Moisture Maps.

Recent questions from growers and consultants have focused on fungicide need and timing and challenges associated with variable crop development for summer 2023.  Given dry conditions, especially prior to mid-June, we may have delayed sclerotial germination that has been triggered by recent rains in some regions. Normally it takes about 3 weeks of wet soil conditions and moderate temperatures for germination and production of apothecia.  This period may be as short as 2 weeks if some moisture was received earlier in June, which may pre-condition sclerotia.  Delayed germination and apothecia development may mean that sclerotinia spore loads in the air are limited as the crop or portions of the crop come into bloom.  This may mean that an early bloom fungicide application may not represent the best target.  However, in crops with reasonable yield potential and where risk tools indicate increasing risk as flowering continues, later fungicide application at full bloom may be considered.  Tools such as the Spornado spore trap (https://2020seedlabs.ca/services/spornado/) and petal testing services (https://www.seedtesting.com/disease-testing-sclerotinia/; https://quantumgenetix.com/product/sclerotinia-white-mold/) can provide guidance related to the level of sclerotinia inoculum and stem rot risk as the crop starts flowering.  Note these need to be combined with other risk tools to provide a complete picture of stem rot risk in relation to host, pathogen and environment factors, i.e. the disease triangle.  If fungicides are being considered, accounting for the most common crop growth stage in a field should be considered to help guide the timing(s) used.  Fortunately, most fungicide products have a window from 20-50% bloom, which represents a range of growth stages.  Note available risk assessment tools will provide information related to stem rot risk and whether a fungicide is needed from 20-50% bloom.

Figure 1.  Percentage of normal soil moisture (drought model) as of June 26, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics.  

Figure 2.  Percent saturated surface soil moisture from SMOS satellite data, June 19-25, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics. 

Figure 3.  Difference from long term average, percent saturated surface soil moisture from the Soil Moisture and Ocean Salinity (SMOS) data, June 19-25, 2023.  Courtesy of Agriculture and Agri-Food Canada's Agroclimate Geomatics and Earth Observation Division.

Disclaimer

Information related to soil moisture is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY. Agriculture and Agri-Food Canada, and their employees assume no liability from the use of this information.  Soil moisture conditions will vary depending on soil texture, and localized rainfall and temperature conditions.  Sclerotinia stem rot risk will vary depending on host, pathogen and weather factors, and farmers and consultants are encouraged to use currently available risk assessment tools (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment).  Mention of a particular product or service does not represent an endorsement by PCDMN or the organizations involved with the PCDMN.

2023 Cereal Rust Risk Report (June 14-20, 2023)

The latest Prairie wind trajectory cereal rust risk report is available for download now at the following link: June 14-20, 2023 report.  

As of the period of June 14-20, 2023 the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows: 

Pacific Northwest – There was moderate number of reverse wind trajectories that passed over the PNW region and into the Prairies and an increase versus June 7-13.  Rainfall has recently occurred especially in central Alberta to the south Peace River region, southern Alberta.  However, given limited stripe rust development in the PNW, as of June 20, 2023 the risk of stripe rust appearance from the PNW is low and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – There was only one trajectory that pass over this source area and ended up in the Prairies and given that crops in the Texas to Oklahoma region are approaching maturity or are being harvested, this source region no longer represents a source of rust inoculum for the Prairie region and the PCDMN cereal risk report will focus on the PNW and Kansas/Nebraska regions.  As of June 20, 2023 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 – Given a lower number of wind trajectories from this region, increasing rust incidence, especially stripe rust, albeit at low levels in this corridor, as of June 20, 2023 the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is generally low and scouting for these diseases in the Prairies is not urgent.  However, recent reports of increasing levels of stripe rust in NW and west central Kansas, and the continued observation of stem rust in Kansas commercial fields may represent an emerging concern. These observations are a concern, however, the number of trajectories was reduced for June 14-20, while rainfall from June 12-18 was limited. Farmers and consultants in the central-eastern Prairies should consider keeping an eye out for stripe and stem rust development, especially in fields planted to susceptible varieties.

Prairie soil moisture maps: June 19, 2023

Prairie soil moisture levels and need to scout for apothecia of the sclerotinia stem rot pathogen, June 19, 2023

 As June 19, 2023 most Prairie regions have well below normal soil moisture with large areas with <40 to 60% of normal levels (Figures 1-3).  However, some areas including the Edmonton region have 85-115% of normal soil moisture levels (Figure 1).  Based on satellite data from June 12-18, 2023, large areas of the Prairies are still dealing with the lingering effects of dry conditions and would only have <5 to 20% surface soil moisture (VMC) (Figure 2).  However, some regions are seeing soil moisture levels increasing somewhat due to recent rains including the Edmonton region, northern cropping areas in Saskatchewan and Manitoba, and southeastern corner of Manitoba (Figure 2).  Corresponding, satellite images for June 12-18 show well below long term average soil moisture levels for large areas of the Prairies including regions where sclerotinia stem rot can occur (Figure 3). However, areas including the Edmonton region are closer to normal.   

As of June 19, the need to scout fields for apothecia of the stem rot fungus and/or to assess in-field risk is low.  This is based on soil moisture maps (Figures 1-3) and that flowering in most canola crops is still two or more weeks away.  However, recent rainfall over some Prairie regions will likely trigger the start of the sclerotial germination process, which can take up to three weeks.  Further rainfall and crop canopy closure may increase the risk of sclerotial germination and apothecia production.  Further soil moisture map updates will help to identify regions where soil moisture conditions are conducive for sclerotial germination.  In these areas in-crop scouting and the use of available stem rot risk assessment tools may be needed as part of fungicide use decisions (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment).

Background information on the soil moisture maps can be found at the following link: New for 2023: Prairie Soil Moisture Maps.

Figure 1.  Percentage of normal soil moisture (drought model) as of June 19, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics.  

Figure 2.  Percent saturated surface soil moisture from SMOS satellite data, June 12-18, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics. 

Figure 3.  Difference from long term average, percent saturated surface soil moisture from the Soil Moisture and Ocean Salinity (SMOS) data, June 12-18, 2023.  Courtesy of Agriculture and Agri-Food Canada's Agroclimate Geomatics and Earth Observation Division.

Disclaimer

Information related to soil moisture is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY. Agriculture and Agri-Food Canada, and their employees assume no liability from the use of this information.  Soil moisture conditions will vary depending on soil texture, and localized rainfall and temperature conditions.  Sclerotinia stem rot risk will vary depending on host, pathogen and weather factors, and farmers and consultants are encouraged to use currently available risk assessment tools (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment).

2023 Cereal Rust Risk Report (June 7-13, 2023)

The latest Prairie wind trajectory cereal rust risk report is available for download now at the following link: June 7-13, 2023 report.  

As of the period of June 7-13, 2023 the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows: 

Pacific Northwest – There was a lower number of reverse wind trajectories that passed over the PNW region and into the Prairies versus May 31-June 6.  Given this, and limited stripe rust development in the PNW and generally dry western Prairie conditions especially in western regions, as of June 13, 2023 the risk of stripe rust appearance from the PNW is low and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – Given limited leaf, stem, stripe and crown rust development in this corridor, and that most crops are approaching maturity or are being harvested, as of June 13, 2023 the risk of stem, leaf, stripe, and crown rust appearance from the Texas-Oklahoma corridor is generally limited and scouting for these diseases in the Prairie region is not urgent. 

Kansas-Nebraska corridor – Given a lower number of wind trajectories from this region, and generally limited leaf, stem, stripe and crown rust development in this corridor, as of June 13, 2023 the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is generally low and scouting for these diseases in the Prairies is not urgent.  However, recent reports of increasing levels of stripe rust in NW and west central Kansas, and the continued observation of stem rust in Kansas commercial fields may represent an emerging concern. These observations are a concern, especially for the central to eastern Prairie regions with rainfall over the last 2-4 days. Farmers and consultants in the central-eastern Prairies should consider keeping an eye out for stripe and stem rust development, especially in fields planted to susceptible varieties.

New for 2023: Prairie Soil Moisture Maps

Background

June is an important month in terms of field crop pathogen and disease development for Prairie farmers.  For cereals and pulses initial leaf disease infections occur and with favourable weather conditions secondary development and spread takes place.  Fungicide use decisions for these leaf diseases can be based partly on disease symptoms, but also consideration of weather and host factors.  Key weather and host considerations include the occurrence of frequent rainfall, moderate temperatures (15-25^oC), level of disease resistance, crop yield potential/canopy density, and commodity prices.  Previous PCDMN posts discussed scouting for leaf disease in cereals and fungicide use decisions.  See: https://prairiecropdisease.blogspot.com/2022/06/scouting-and-risk-assessment.html.

 

For diseases such as sclerotinia stem rot of canola and ergot of small grain cereals, suitable pathogen development must occur to produce spores before host infection can take place.  The pathogens associated with both diseases overwinter as resting bodies known as sclerotia, which are compact masses of hyphae (Figure 1).  Germination of stem rot sclerotia to produce the golf-tee shaped apothecia, aka carpogenic germination, requires sufficient soil moisture and moderate temperatures.  Typically, germination takes up to three weeks with the occurrence of temperatures that range from 10 to 20^oC with soil water potentials of about 0 to 500 kPa, although germination is reduced as kPa increases to >=300-500 kPa (Abawi and Grogan 1975; Boland 1984; Boland and Hall 1988; Clarkson et al. 2004; Hao et al. 203; Teo and Morrall 1985a,b).  These conditions typically occur for Prairie crops with adequate rainfall following canopy closure over the soil surface, which helps to buffer temperature and moisture fluctuations. 

 

Soil water (matric) potential is a measure of how closely water is held by soil particles and pores (Datta et al. 2017; Irmak 2019).  Soil volumetric water content (VWC) is related to the ratio of soil water volume and the volume of the soil and is expressed in percentages.  The relationship between VMC and soil matric potential varies depending on soil texture and is expressed through a soil water characteristic curve for each soil type .  When soils approach saturation (0 kPa) the VMC will be up to 45% for clay textured soil, while for sandy soils this value is 30%.  Once soil water potential increases above 300 kPa plant root access to water will be increasingly difficult, while for soils overall the permanent wilting point of a plant is generally considered to be reached around 1,500 kPa (Datta et al. 2017).

  

PCDMN weekly soil moisture maps

 Starting in mid to late June in 2023 the PCDMN will be posting weekly soil moisture maps to help farmers and consultants identify regions where rainfall has occurred, and soil moisture levels are potentially favourable for germination of sclerotia and production of apothecia of the stem rot pathogen.  For regions with favourable soil moisture conditions, farmers and consultants are encouraged to scout for apothecia and also use in-field sclerotinia stem rot risk assessment tools including the checklist, as well as measures of aerial spore load via petal testing or spore trapping (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment).  Fungicide use and timing decisions can be improved by using these sources of information. 

 

PCDMN related information for sclerotinia stem rot can be found here:

https://prairiecropdisease.blogspot.com/p/scouting-tips-calendar.html

https://twitter.com/pcdmn/status/1143545235789811712

https://prairiecropdisease.blogspot.com/2022/08/prairie-crop-disease-monitoring-network.html

https://prairiecropdisease.blogspot.com/2020/08/suggested-protocols-for-assessing.html.

 

The PCDMN has been working with Agriculture and Agri-Food Canada (AAFC) to obtain maps showing surface soil moisture based on satellite observations.  These soil moisture values are in VMC and usually range from 5- 45% by volume and the relationship between this value and the plant available water are affected by soil texture.  For example, a dry sandy soil may have a volumetric moisture content as low as 5% when dry, whereas the lower bounds for a clay textured soil may be closer to 20% VMC.  Soils with a VMC of 40-60% would be wet/saturated, although the level of saturation would vary based on soil texture, where a sandy soil may be saturated at 30% compared to 40-60% for heavier textured or organic soils.

 

In addition to total soil moisture (i.e., VMC), AAFC also provides maps showing the % difference from average over a specified period. Here +ve values indicates the moisture is wetter than normal, while a –ve value indicates it is dryer than normal.  When you have a high percentage difference, this would indicate the soil is either much wetter or much drier than normal.

  

Prairie soil moisture levels and need to scout for apothecia of the sclerotinia stem rot pathogen, June 12, 2023

 

As June 12, 2023 most Prairie regions have well below normal soil moisture levels with large areas with <40 to 60% of normal (Figure 2).  Based on satellite data from June 5-11, 2023, large areas of the Prairies would only have <5 to 20% surface soil moisture (VMC) and as Figure 3 indicates, the corresponding satellite image shows well below long term average soil moisture levels for large areas of the Prairies including regions where sclerotinia stem rot can occur (Figure 4). 

 

As of June 12, the need to scout fields for apothecia of the stem rot fungus and/or to assess in-field risk is low.  This is based on soil moisture maps (Figures 2-4) and that flowering in most canola crops is still 2-3 weeks away.  

  

Disclaimer

 

Information related to soil moisture is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY. Agriculture and Agri-Food Canada, and their employees assume no liability from the use of this information.  Soil moisture conditions will vary depending on soil texture, and localized rainfall and temperature conditions.  Sclerotinia stem rot risk will vary depending on host, pathogen and weather factors, and farmers and consultants are encouraged to use currently available risk assessment tools (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/#forecasting-and-risk-assessment).

 

 References

 

Abawi, G.S., and R.G. Grogan. 1975. Source of primary inoculum and effects of temperature and moisture on infection of beans by Whetzelinia sclerotiorum. Phytopathology 65: 300-309.

Boland, G.J. 1984. Epidemiology and management of diseases caused by Sclerotinia sclerotiorum in whitebean and soybean. Ph. D. thesis, Univ. of Guelph, Guelph, Ontario. 245 pp.

Boland, G. J., and Hall, R. 1988. Epidemiology of Sclerotinia stem rot of soybean in Ontario. Phytopathology 78:1241-1245.

Clarkson, J. P., Phelps, K., Whipps, J. M., Young, C. S., Smith, J. A., and Watling, M. 2004. Forecasting Sclerotinia disease on lettuce: Toward developing a prediction model for carpogenic germination of sclerotia.  Phytopathology 94:268-279.

Datta, S., Taghvaeian, S., and Stivers, J.  2017.  Understanding Soil Water Content and Thresholds for Irrigation Management.  Oklahoma Cooperative Extension Service, BAE-1537, June 2017.  Division of Agricultural Sciences and Natural Resources, Oklahoma State University. 

Grogan, R.G., and Abawi, G.S. 1975.  Influence of water potential on growth and survival of Whetzelinia sclerotiorum. Phytopathology 65: 122-128.

Hao, J. J., Subbarao, K. V., and Duniway, J. M. 2003. Germination of Sclerotinia minor and S. sclerotiorum sclerotia under various soil moisture and temperature combinations. Phytopathology 93:443-450.

Irmak, S. 2019.  Soil water content – and soil matric potential-based irrigation trigger values for different soil types.  Institute of Agriculture and Natural Resources, CropWatch, University of Nebraska-Lincoln. https://cropwatch.unl.edu/2019/SWC-SMP-irrigation-trigger-values.

Teo, B. K., and Morrall, R. A. A. 1985a. Influence of matric potentials on carpogenic germination of sclerotia of Sclerotinia sclerotiorum. 1. Development of an inclined box technique to observe apothecium production. Can. J. Plant Pathol. 7:359-364.

Teo, B.K., and R.A.A. Morrall. 1985b. Influence of matric potentials on carpogenic germination of sclerotia of Sclerotinia sclerotiorum. II. A comparison of results obtained with different techniques. Can. J. Plant Pathol. 7: 365-369.

Figure 1.  Disease cycle of sclerotinia stem rot of canola.  Courtesy of Taryn Dickson, Resource Manager, Crop Production and Innovation and the Canola Council of Canada (https://www.canolacouncil.org/canola-encyclopedia/diseases/sclerotinia-stem-rot/).

Figure 2.  Percentage of normal soil moisture (drought model) as of June 12, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics.  

Figure 3.  Percent saturated surface soil moisture from SMOS satellite data, June 5-11, 2023.  Courtesy of Agriculture and Agri-Food Canada's Science and Technology Branch, AAFC Geomatics.

Figure 4.  Difference from long term average, percent saturated surface soil moisture from the Soil Moisture and Ocean Salinity (SMOS) data, June 5-11, 2023.  Courtesy of Agriculture and Agri-Food Canada's Agroclimate Geomatics and Earth Observation Division.

2023 Cereal Rust Risk Report (Mini update for June 7-13, 2023)

The full weekly cereal rust risk report for June 7-13, 2023 will be delayed as we are waiting on location specific wind trajectory data for the Pacific Northwest (PNW) and the Kansas/Nebraska (KS/NE) regions. 

However, in terms of total trajectory numbers there was a substantial reduction in the number of trajectories from the PNW (40 versus 104 last week), Texas/Oklahoma (TX/OK)  (17 versus 98 last week), and KS/NE (46 versus 119).  Note most of the KS/NE and TX/OK trajectories would have primarily passed over locations in Saskatchewan and Manitoba, while trajectories from the PNW would have mainly passed over locations in Alberta and western Saskatchewan.  

A recent update from Dr. Chen, USDA ARS/WSU, Pullman, WA (Rust update June 13, 2023, https://striperust.wsu.edu/?post_type=post&p=3639) continues to indicate limited development of stripe rust in commercial cereal fields.  However, observations of increased levels were noted in a number of screening trials for both winter and spring wheat and barley. Dr. Chen indicates that the "rust season" is over for winter wheat, although recent rains and moderate temperatures may favour development in spring cereal crops. 

Previous PCDMN cereal rust risk reports indicated limited rust development in Texas and Oklahoma.  These regions are likely no longer a significant source of rust inoculum given that most winter wheat and oat crops are likely mature with 42 and 28% of the winter wheat and 60 and 5% of the oat crops being harvested as of June 11, 2023, for Texas and Oklahoma, respectively (https://quickstats.nass.usda.gov/results/5803D4B1-7DF2-36E9-B294-11222030BF1A; https://quickstats.nass.usda.gov/results/08843EBD-FC53-33BC-BD7F-81F3751B687C).  

Over the last week there continue to be reports of stripe rust and stem rust in winter wheat from Kansas.  In general, the levels of leaf, stripe and stem rust are low, although on susceptible varieties low-moderate stem rust levels were recently observed in Republic County, North Central Kansas (Dr. K. Onofre, Stem Rust Detection in Kansas, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 13, 2023; Dr. E. DeWolf, More stem rust activity in Kansas, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 14, 2023). 

Recently Dr. E. DeWolf, indicated that moderate amounts of stripe rust have been reported from Northwest Kansas (Dr. E. DeWolf, More stem rust activity in Kansas, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 14, 2023; Dr. E. DeWolf, Stripe Rust Update from Kansas, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 15, 2023; Figures 1 and 2).  In their June 15 update Dr. De Wolf reports that  levels of stripe rust were low in mid-May in central Kansas, while in west central and NW areas the disease moved in late as crops were moving into head emergence and anthesis.  In these NW and west central areas susceptible varieties are now showing high incidence and moderate severity levels.  Overall, Dr. De Wolf reports that stripe rust appearance was delayed in 2023.  

Figure 1.  Distribution of stripe rust in Kansas as of June 6, 2023. Dr. K. Onofre, K-State Research and Extension (https://t.co/cpEUoaxJ3L).

Figure 2.  Distribution of stripe rust in Kansas as of June 14, 2023. Based on input from K-State Research and Extension: E. De Wolf, K. Anderson Onofre, R. Lollato, J. Falk Jones Consultants and Ag. Industry: J. Kohls, M. Padgham (Dr. E. DeWolf, Stripe Rust Update from Kansas, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 15, 2023).

Previous PCDMN cereal rust risk reports indicated a lack of stripe and leaf rust on winter wheat crops in Nebraska in late May and early June.  However, recent rains and lower temperatures may favour rust development, but given later crop growth stages and potential late arrival of stripe rust spores, yield losses are not expected to be significant (Dr. S. Wegulo, Update from Nebraska, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, June 14, 2023).  

As of the period of June 7-13, 2023, the overall Prairie cereal rust risk assessment and need for in-crop scouting is as follows: 

Pacific Northwest – There was a lower number of reverse wind trajectories that passed over the PNW region and into the Prairies versus May 31-June 6.  Given this, and limited stripe rust development in the PNW and generally dry Prairie conditions especially in western regions, as of June 13, 2023 the risk of stripe rust appearance from the PNW is low and scouting for this disease in the Prairie region is generally not urgent.

Texas-Oklahoma corridor – Given limited leaf, stem, stripe and crown rust development in this corridor, generally dry eastern Prairie conditions and that most crops are approaching maturity or are being harvested, as of June 13, 2023 the risk of stem, leaf, stripe, and crown rust appearance from the Texas-Oklahoma corridor is generally limited and scouting for these diseases in the Prairie region is not urgent.  

Kansas-Nebraska corridor – Given a lower number of wind trajectories from this region, generally limited leaf, stem, stripe and crown rust development in this corridor, and generally dry eastern Prairie conditions (Figure 3), as of June 13, 2023 the risk of stem, leaf, stripe, and crown rust appearance from the Kansas-Nebraska corridor is generally low and scouting for these diseases in the Prairies is not urgent.  However, recent reports of increasing levels of stripe rust in NW and west central Kansas, and the continued observation of stem rust in Kansas commercial fields may represent an emerging concern.  These observations are a concern, especially for the central to eastern Prairie regions with rainfall over the last 2-4 days.  Farmers and consultants in the central-eastern Prairies should consider keeping an eye out for stripe and stem rust development, especially in fields planted to susceptible varieties.

Figure 3. Seven day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 5-11, 2023.

Sclerotinia Risk Assessment Tool – Beta-testers needed for the 2023 season

The availability of plant disease risk assessment tools to guide farmers and the crop consultants they are working with is an important component of the fungicide decision process. 

To help guide farmers and crop consultants with sclerotinia stem rot risk assessments a tool has been developed.  Chris Manchur, Agronomy Specialist – Eastern Manitoba, Canola Council of Canada, has provided a short blurb that outlines the objectives and process for the sclerotinia risk assessment tool.  

Sclerotinia Risk Assessment Tool – Beta-testers for the 2023 season: 

In collaboration with Agriculture and Agri-Food Canada and SeedWorld Group, the Canola Council of Canada is developing a risk assessment tool to help growers make timely decisions on whether a foliar fungicide application is advised. For 2023, we are looking for beta-testers to use this tool and confirm whether a recommendation is accurate for that growing area. Our 2023 target is 100 fields surveyed across western Canada.

What would I need to do?

1) At fungicide decision time (early flowering), visit your test field and enter the following field information (multiple choice options): precipitation in the past two weeks, forecasted precipitation, plant density, years since last host crop, sclerotinia severity in last host crop, and presence of spore-producing apothecia in the field. Your risk score and spray recommendation based on these factors will be provided.

2) If spraying a fungicide, use the two marker flags provided by the CCC to leave an unsprayed check strip.

3) Revisit your test field at 30 – 60% seed colour change and assess sclerotinia severity on 100 plants in both sprayed and unsprayed parts (if you left a check strip) on a 0-5 scale. In addition, collect sclerotia/infected stem pieces for AAFC to test fungicide resistance.

4) Collect your gift card upon completion!

How do I sign up?

Beta-testers can sign up by contacting Chris Manchur, CCC Sclerotinia Lead, at manchurc@canolacouncil.org. Testers who complete both steps will be eligible for a gift card and are eligible for one gift card per field submitted (no limit to the number of fields that can be submitted). A link to the tool's website, markers flags, and postage-paid collection envelopes will be provided in early-mid June.