July 15 Quiz — Sclerotinia stem rot risk

July 15, 2015 - Issue 17

At this stage of the season, severe stem infection will start to look like this. Source: Debbie McLaren, AAFC

The risk of stem infection like this is overall lower this year, given the dry conditions leading up to flowering in many regions. But a risk assessment is still worth the time. Source: Debbie McLaren, AAFC

1. What is generally considered the canola yield threshold at which a fungicide application for sclerotinia stem rot is more likely to provide a return on investment?
2. What is this flowering stage?

Fungicide applied late in the window can provide valuable protection from sclerotinia stem rot if flowering is extended or if conditions become more conducive to disease.
3. Apothecia, the little mushrooms that disperse sclerotinia spores, need moist soils to germinate. If a few rains improve the soil moisture situation and apothecia start to germinate, how many days does it take, generally, from the start of germination until the apothecia disperse spores?

Sclerotinia apothecia are quite small. Source: Faye Dokken-Bouchard, Saskatchewan Ministry of AgricultureSclerotinia apothecia. Source: Faye Dokken-Bouchard, Saskatchewan Ministry of AgriculturePhoto source: Faye Dokken-Bouchard, Saskatchewan Ministry of Agriculture

 

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