Factsheet DSS potato late blight Hutton criteria

Potato late blight can cause severe damage to potato leaves and tubers. Potato late blight is a disease caused by a fungus-like organism (Phytophthora infestans) that spreads rapidly in the potato crop canopy and can also infect tubers. Control with help of DSS on platform.ipmdecisions.net This model runs during the potato growing season and relevant as soon as the crop emerges. The model determines when weather conditions create high risk of infection, to guide targeting of fungicide treatment. The model uses daily air temperature and humidity. A high risk ‘Hutton Criteria’ period occurs when two consecutive days have a minimum temperature of 10°C, and at least six hours of relative humidity at or above 90%. Susceptibility of varieties is not taken into account. The risk information can be used for the timing of fungicide applications. There are many fungicides on the market with different modes of action. Information about properties of fungicides is available through Euroblight, a potato late blight network for Europe: https://agro.au.dk/forskning/internationale-platforme/euroblight/control- strategies/late-blight-fungicide-table This DSS was adapted from work carried out in The UK and is not tested yet in other countries yet.