By John Ippolito, PAg, Regional Crop Specialist, Kindersley
We are already half way through the growing season, but there are still some decisions that may have to be made in the next few weeks. These surround crop pests that are either just coming on to the scene or where risks are changing because of environmental conditions. The most common of these are insects, such as wheat midge and bertha armyworm, and diseases, such as fusarium head blight and sclerotinia.
There are provincial risk assessments done on both wheat midge and bertha armyworm that are updated regularly to indicate regional risk of these insects occurring. In the case of wheat midge producers can refer to the Prairie Pest Monitoring Blog for a snapshot of emergence of wheat midge adults based on growing degree days. The map to be used is the Growing Degree Map base 5 degrees. Wheat midge adults start emergence at approximately 650 growing degree days. This map can be used as an indicator of whether your crop is at risk depending on its staging in relation to predicted adult emergence.
There are a number of co-operators around the province that maintain traps and submit adult bertha armyworm moth counts on a weekly basis starting in mid-June. These counts are reported to the public in the form of a provincial map. Areas that are shown to have cumulative moth counts of 600 or more may be at risk of crop damage that warrants control measures.
The Saskatchewan Wheat Development Commission maintains a fusarium risk map on their website that can be used as an indicator of fusarium infection risk for wheat crops. The map is created using models that include temperature and/or humidity in the previous few days plus the forecasted weather for the next few days to reflect risk of fusarium infection.
Other diseases such as sclerotinia of canola and anthracnose in lentils do not have the same sort of risk maps, but there are scorecard tools available that can be used in decision making for fungicide application based on weather conditions. These can be found on the Canola Council of Canada and Saskatchewan Pulse Growers websites.
It is important to note these resources are tools to help in decision making. The risk maps in particular are an indicator of risk on a regional or provincial scale, but may not accurately reflect what is happening in an individual field. They may be used to assist in determining the amount of time that may be required for scouting, or whether your crop is beyond the stage of being at risk.
For more information on the use of these tools, contact your Saskatchewan Ministry of Agriculture Regional Crop Specialist.