CANOLA QUIZ – Sclerotinia risk for 2021

Open canopies, lower soil and canopy moisture, and early flowering will reduce risks for sclerotinia stem rot on many farms across the Prairies in 2021. This quiz will help agronomists and farmers assess the risk for each field.

1. Dry conditions at the beginning of flowering can change to wet conditions during flowering, which may increase disease risk. However, keep in mind that it takes __________ for sclerotia to germinate and produce the spores necessary for infection.

two to three hours

two to three days

two to three weeks

two to three years

2. When does the application window close for most sclerotinia stem rot fungicides?

Start of flower

After full flower

End of flowering

Time of swathing

3. The sclerotinia pathogen doesn't like hot weather and fungicide performance is reduced in hot weather. Fill in the blank in this sentence: The disease risk is limited when current conditions are dry, and max daily temps are ___ or more.

20°C

25°C

30°C

35°C

4. We talk often about the benefits of uniform emergence, with all plants at the same stage. That sure helps when it comes to fungicide timing. Of course, things don't always work out that way. Which of the following would be the most accurate agronomy statement for fungicide timing in an uneven crop?

Consider spraying when the earliest plants are at the right stage because early infections usually cause the most yield loss.

Uneven crops are too much of a bother. Just ignore them.

Consider spraying when the latest plants are at full flower as this will provide a curative response for the greatest number of plants.

Uneven crops should be sprayed twice because a single application timing is too hard to judge.