By Erica Yaskowich, BSc, Ag Dip, AAg, Crops Extension Specialist, Kindersley, RSB
July 2024
Plant diseases can be detrimental to field crops if the conditions are ideal for the diseases to flourish. The conditions that have been present this spring and summer, so far, are conducive for diseases to take hold within crops.
Plant diseases can become established when the soil is moist after rain and there is humidity within the crop canopy. Spores can bounce up with raindrops and soil particles onto the lower leaves of plants, be introduced by insects or be wind blown. Warm, moist and humid conditions often favour the spread of most crop diseases.
![Apothecia for Sclerotinia sclerotium that were been found in a mustard crop. With ideal moisture conditions, these apothecia can emerge. Apothecia for Sclerotinia sclerotium that were been found in a mustard crop.](https://www.saskatchewan.ca/-/media/images/agriculture/cpn/2024-05/fungicide-applications.png?h=263&w=300&hash=582BD07493D5681CB2DFFCEAFBAA36CB)
When considering a fungicide for your crop, there are some things to keep in mind. The first step is scouting. Observing your crop throughout the growing season can assist with early detection and monitoring the level of disease in your crop. Previous crops and patches within fields that have had heavy disease pressure can result in problem areas. When assessing disease pressure look at all the leaves carefully while keeping in mind that the flag and penultimate (upper) leaves in cereals and pulses are responsible for most of the seed filling of the crop and total yield.
Timing of the fungicide application is important for disease suppression or control, so frequent scouting is encouraged for diseases that can infect crops at multiple times. For diseases with one infection timing per year, like sclerotinia and Fusarium head blight, fungicide application has to take place before disease symptoms appear.
Taking pictures of the diseased plant parts and collecting plant samples will help to positively identify what is affecting the crop. Get help from your local Crops Extension Specialist or agronomist who can assist in identifying the disease and discuss control options. For difficult to diagnose diseases or for positive confirmation of your findings, plant samples can be submitted to the Saskatchewan Crop Protection Laboratory.
Once confirmation has been made, and the level of infection warrants treatment, the proper fungicide can be applied. If there has been disease present in the field and conditions are conducive for disease development or spread, preventative measures may need to be taken.
Disease surveys are completed every year by the Ministry of Agriculture, the Saskatchewan Association of Rural Municipalities (SARM) and industry. These surveys help with tracking diseases throughout the province. These survey maps can show trends of disease movement and patterns.
For more information on how fungicides work, check out the Guide to Crop Protection.