An advisory service for the occurrence of Phytophthora infestans on tomato in Emilia‐Romagna region1

Abstract

The Emilia‐Romagna region is one of the leading areas in Italy for its high production of industrial tomatoes. A warning service for the occurrence of late blight caused by Phytophthora infestans has been operating for 3 years in the region. Its aim is to reduce the number of sprays which are usually carried out on tomato crops to prevent the disease (7–8 sprays depending on year and area). Climatic data from weather stations covering all the region is used by the warning service to inform farmers every week of the risk of disease occurrence and provide them with precise spray recommendations for blight control. A forecasting model based on climatic data (IPI Model; Infection Potential Index) has been elaborated by the Plant Protection Service of Emilia‐Romagna region and is now used together with a network of unsprayed tomato plots and, in the high‐risk areas, with aerobiological monitoring of P. infestans sporangia. The IPI Model uses daily data on temperature, RH and precipitation, and shows good reliability for ‘negative prognosis’ of the disease; the other forecasting parameters become more important when the risk is higher. This warning service has allowed growers to reduce sprays by 50% on average. Further reduction in treatments should be possible, especially in low blight‐risk areas.