QUIZ – Sclerotinia stem rot risk

These three questions will help canola farmers and agronomists assess the sclerotinia stem rot risk in their areas.

1. The disease triangle describes the three essential requirements for plant disease to occur. You need the pathogen present in the field. You need a host  – a crop that is susceptible to infection by that particular pathogen. What is the third requirement?

2. Relative humidity (RH) is a good indicator of adequate moisture for disease. Daily minimum RH of over ____ per cent from about two weeks before flowering and through flowering will provide the humid conditions needed to promote disease development.
3. Hot weather can limit the risk from sclerotinia stem rot. The pathogen's preferred range is 10°C to 25°C. However, to reduce the disease risk enough to eliminate the need for a fungicide application, hot days should also be combined with which of the following?