Sclerotinia infection risk alerts (forecast) for oilseed rape

If spores are present, conducive weather is required for infection to occur.

Based on observed (past 24 hours) and forecast (next 72 hours) weather data, the interactive maps track the period of time that relative humidity (RH) and air temperatures are at or above threshold (80% and 7°C, respectively).

If these thresholds are exceeded for 23 continuous hours (the time needed in order for sclerotinia to infect the crop), a weather-based infection alert is issued at the corresponding site (dark blue circle). Near misses are also highlighted (light blue circles). Where infection risk is low, this is shown (green circles).

Click on a circle (any colour) to show an hour-by-hour chart of the sclerotinia infection risk for that site.

Sclerotinia control products are protectants and should be applied prior to infection (before circles turn blue).

Our weather-based sclerotinia infection risk alerts support decisions. When thresholds for temperature and humidity are met, a risk-alert is triggered. However, forecast weather data is not always accurate.

Here we analyse how good the predictions were during the 2021 season, in relation to risk alerts.

The 2021 risk period was relatively cool, which delayed flowering and extended the flowering period. It also resulted in a relatively low number of weather-based infection risk alerts and, generally, low spore levels.

Our analysis shows that forecast alerts were 91.5% accurate (Table 1), when compared to actual weather during the period 15 March to 23 June 2021.

Differences tend to be due to relative humidity (which is harder to forecast, due to localised showers and local factors) rather than temperature, and this is particularly true in costal locations.

Table 1. Accuracy and classification of forecasted vs observed alerts

Video notes:

• Spore data is no longer published as part of the alerts service
• The colours used to indicate infection-risk status have changed since the video was published