Understanding the Saskatchewan and Manitoba FHB Risk Maps

Written & Submitted on July 22, 2015 by: Faye Dokken-Bouchard (Plant Disease) and Mitchell Japp (Cereal Crops), Provincial Specialists, Saskatchewan & Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba

For the first time in 2015, FHB risk maps are available in both Saskatchewan and Manitoba. At a glance, on a given day the maps may appear to indicate a different risk for growers in each province, which can be concerning for farms along the Manitoba-Saskatchewan border. However, closer examination will reveal minor differences in the models and maps useful for considering FHB risk.

In Saskatchewan, maps are created with models (depending on spring or winter wheat) using temperature and/or relative humidity in the previous 5 days, plus 2 days forecast. While in Manitoba, maps are created with a model that uses the hours of precipitation and the hours with temperatures between 15°C and 30°C during the previous 7 days. Each province then has its own categorization based on slightly different threshold values – low, moderate, high (and extreme in Manitoba) – based on the output from their respective models.

Models are also constantly validated and fine-tuned for the region where it is relevant. The model that is best for the Fusarium population and conditions in individual provinces in western Canada, or even across the border in the USA, might not be the same. However, crop scientists and pathologists continue to work together to determine how FHB risk maps can be most valuable to all farmers, including those along the border! Producers along the border may have a potential advantage in assessing risk, by using both maps and interpreting which one is most relevant for their farm. And keep in mind risk maps may not perfectly represent a producer’s individual field(s).

Regardless of the model used, no FHB risk map can be taken as a stand-alone tool to make management decisions about FHB as it only takes into account environment. The existence of disease requires 3 factors: the interaction of a susceptible host, a virulent pathogen, and an environment favourable for disease development. So although a risk map in Saskatchewan or Manitoba may show High risk due to environment, disease risk may be low if the wheat crop is not at the proper stage for infection.

We strongly encourage referring to additional information and consultation with local extension specialists and agrologists to determine if fungicide applications are needed to suppress FHB in your area.

If you have any questions on the FHB Risk maps or FHB management, please contact Manitoba Agriculture or the Saskatchewan Ministry of Agriculture.

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Early Indications of Winter Wheat Survival in 2015

The ability of the winter wheat plant to survive the winter often depends on its ability to withstand low temperatures. Through the process of “cold acclimation” the plant acquires cold tolerance or winter hardiness. Factors that can impact the level of cold hardiness of the plant include weather, fertility, seeding date, and seeding depth.  For the 2014/15 winter wheat crop, majority of acres would likely be considered “well-hardened”.

Measuring Soil Temperature.  MAFRD has been measuring soil temperatures in four winter wheat fields throughout the 2014/15 winter (see CropChatter post http://cropchatter.com/monitoring-real-time-soil-temperatures-in-mb-winter-wheat-fields/).  Plotting soil temperatures against various ‘hardiness” curves can provide an early indication if there is a concern for winter injury or winterkill.

The figure below illustrates the soil temperatures, measured at a 1″ depth, in four winter wheat fields across Manitoba, plotted against various ‘hardiness’ curves.

Figure 1: 2014/15 Soil Temperatures Measured at 1 Inch Depth in Four Winter Wheat Fields

2014.15 Soil Temperatures - Winter Wheat Fields

Data Source:  MAFRD AgWeather Program

Since majority of winter wheat acres are considered “well-hardened” and soil temperatures didn’t reach levels that went below the “high hardiness’ curve, winterkill isn’t expected to be a large concern.  However, since soil temperatures at one location did dip below the “mid hardiness’ curve, or at some locations got close to that curve, some areas within fields may be impacted.

Early Assessment of Growth.  From early reports of producers and agronomists bringing in winter wheat plants from the field or conducting the ‘bag test’ to assess winter survival, regrowth has been noted which is also good news. Continued scouting is encouraged though as fields start to break dormancy and growth resumes with earnest.

So between early assessments and the measured soil temperatures, winter wheat survival looks promising to date.  Keep in mind these early indicators shouldn’t stop you from assessing your own winter wheat fields though. As well, the weather in the coming weeks will play a large role in telling the final story of winter wheat’s survival.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD


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Cooler Temperatures Prevailing So Far in 2014

In the June 16th Issue of the Manitoba Crop Report, it was noted that cooler than normal temperatures have slowed crop development slightly.  So how cool has it been in Manitoba to date?

Mike Wroblewski, MAFRD’s Ag Meteorologist who runs the Manitoba AgWeather Program, has created the following maps showing Accumulated Growing Degree Days (GDD) and Corn Heat Units (CHU) to date, as well as Percentage of Normal Accumulation for GDD and CHU, up to June 15th.

Accumulated Growing Degree Days (GDD) – May 1 to June 15, 2014

Percentage of Normal GDD – May 1 to June 15, 2014

Accumulated Corn Heat Units (CHU) – May 1 to June 15, 2014

Percentage of Normal CHU – May 1 to June 15, 2014

More information on the Manitoba Ag-Weather Program can be found at http://tgs.gov.mb.ca/climate/Default.aspx


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