Sclerotinia Stem Rot Checklist
Sclerotinia incidence can vary greatly among fields and years, making scheduled spraying of fungicides unprofitable. However, when sclerotinia risk is high, preventative fungicide applications can effectively lower disease severity and improve yield. Assessment of disease risk within each field is essential to improve the odds that fungicides are only applied when it is economical to do so.
This checklist developed in Sweden can be useful in helping to assess disease risk in fields. Growers should fill out the checklist for each field shortly after first flower (when 75% of the canola plants have at least 3 open flowers). The greater the risk score for a field the higher the probability of a positive economic return. Results in Sweden have suggested that fields scoring 40 or higher will likely benefit from a fungicide, but this may vary a bit depending on fungicide cost and commodity price.
Something else that may affect the risk profile of a field is the genetics that have been chosen. Research has shown that there is a correlation between lodging and sclerotinia levels, and susceptibility to lodging can be related to genetics. As well, the introduction of varieties with some tolerance to sclerotinia into the marketplace offers an additional management tool that may reduce the risk in fields where they are grown.
The decision whether to apply a fungicide for control of sclerotinia stem rot in canola is the sole responsibility of the grower. AAFC cannot guarantee the accuracy of sclerotia-depots and risk points assigned to sclerotia germination in the modified sclerotinia stem rot checklist.