Understanding the Saskatchewan and Manitoba FHB Risk Maps
Faye Dokken-Bouchard (Plant Disease) and Mitchell Japp (Cereal Crops), Provincial Specialists, Saskatchewan Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba
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 differing threshold values - low, moderate, high (and extreme in Manitoba) to illustrate the output from their respective models.
Map on left shows FHB risk based on relative humidity in previous 5 days plus 2 days forecast for Saskatchewan spring wheat crops heading on July 22; map on right shows FHB risk based on temperature and precipitation in previous 7 days for Manitoba wheat crops flowering on July 22.
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 U.S., 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 to determine which is most relevant to their farm. Risk maps are designed to be as accurate as possible but they may not 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 the environment into account. The existence of disease requires 3 factors: the interaction of a susceptible host, a virulent pathogen, and an environment favourable for disease development. Although a risk map in Saskatchewan or Manitoba may show high risk due to environment, disease risk may actually be low if the wheat crop is not at the proper stage for infection.
We strongly encourage referring to additional information and consulting with local extension specialists and agrologists to determine if fungicide application is needed to suppress FHB in your area.
If you have any questions on the FHB Risk maps or FHB management, please contact Manitoba Agriculture Food and Rural Development, or the Saskatchewan Ministry of Agriculture.
Additional information on FHB:
https://www.gov.mb.ca/agriculture/crops/plant-diseases/scouting-control-fusarium-head-blight.html