By Eileen Beaton, PAg, Crops Extension Specialist, Weyburn
December 2024
Without adequate prevention and treatment, diseases have the potential to damage crops. Winter is a great time to review the previous season and consider crop disease strategies to help you plan for a successful season ahead. Scouting crops weekly throughout the growing season can help identify diseases before crop loss occur. The proper procedure for scouting is to walk in an inverted W-shaped pattern starting at least 30 metres from the edge of each field. At least 10 plants at each of the five points along the W pattern should be assessed. When assessing disease presence and severity, inspect the leaves and roots for discolouration and/or discoloured spots, then record the findings. Photos in field guides such as the Crop Diagnostic Handbook can help in identifying diseases and other stressors that appear similar. If you are unsure of the disease, plant samples can be collected and submitted to the Crop Protection Lab in Regina for diagnosis.
Identifying diseases early can provide the time necessary to choose and apply a foliar fungicide. For a list of products registered for control, refer to the Crop Protection Guide. In some cases, additional applications may be required depending on disease severity.
It is important to be aware of when problematic diseases could arise. Scouting more frequently during these times can be beneficial to a timely diagnosis. Seedling disease symptoms can appear in any crop and will usually be apparent shortly after emergence. Sclerotinia stem rot symptoms can start to appear just prior to or during the flowering stage in canola. Many of the later season diseases including fusarium head blight or ergot may not be evident before the critical fungicide application timing is due. In these cases, monitoring environmental conditions for increased rainfall and high humidity can be an indicator of the potential for increased disease pressures. Weather station data from organizations including the Government of Canada can be used for this. To receive an assessment of potential fusarium head blight damage to cereal crops in your area, refer to the Fusarium Head Blight Risk Mapping Tool.
Other stressors can easily be mistaken for disease. Nutrient deficiencies/toxicities, herbicide injury, insect damage or poor environmental conditions can cause plants to appear diseased. It is important to consider all potential stressors when scouting. Considering recent weather events and reviewing field records for details on crop input applications and previous crops planted can help prevent unnecessary fungicide applications and ensure all other stressors are addressed separately.
Implementing biosecurity practices can prevent the movement of soil-borne diseases including clubroot. Procedures such as scouting fields that are known to have the least disease pressures first and knocking off as much soil as possible from your boots when you leave a field are a good start. Further measures such as cleaning boots and any equipment used with a disinfectant solution of two per cent sodium hypochlorite (the active ingredient found in bleach) can improve biosecurity. Wearing disposable plastic boot covers is also an option.
Identifying diseases in crops early can help minimize crop damage and ensure timely foliar fungicide application if needed. For more information, call the Agriculture Knowledge Centre at 1-866-457-2377 to speak with your local crops extension specialist or consult an agronomist.