A large body of work was undertaken by JHI, funded by AHDB Potatoes, to identify precisely what new criteria might produce the optimum Blight risk prediction results.
Experimental investigations showed that:
- Reducing the minimum temperature did not improve alert performance markedly
- The relative humidity threshold should not change
- Reducing both temperature and relative humidity criteria resulted in an overly sensitive alert system
- Shortening of the duration of high relative humidity proved most effective
Now: The Hutton Criteria
Two consecutive days:
- Each day has a minimum temperature of 10°C
- Each day has at least six hours with relative humidity ≥ 90%
- Performance up from 41 to 69 % of > 2000 historic potato late blight outbreaks receiving an alert
- Increased proportion of days receiving an alert from 7 to 16% for a 28% gain in performance
- Improved consistency in alert performance across all regions of Great Britain
- The future for Blight modelling and alert systems.