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Prediction and warning system in Chile: A way to face the risk of late blight

Ivette Acuna: Agricultural Research Institute INIA Chile

<div>There is a large amount of weather information available that can be accessed to enable forecasting using a decision support system (DSS) for development of integrated pest management for late blight. In Chile, late blight DSS forecasting system based on Blitecast has been available since 2007. This system utilizes weather station data to predict late blight risk which is delivered to the farmers through a web page, SMS and e-mail ( A survey shows that 42% of the registered farmers use the system to make fungicide application decisions. To improve the opportunity of application and efficacy of chemical control, an early warning system using weather prediction data has been evaluated. Field experiments have been performed during 3 crop seasons to evaluate the system using 24, 48 and 72 hour forecast data to monitor incidence and severity of late blight. Disease severity was different for each crop season. No significant differences in disease damage were found using weather station data, weather prediction data (24, 48 y 72 hrs) or scheduled application (RAUDPC: 0.06, 0.05, 0.02, 0.01, 0.05, respectively) but all treatments were better than the untreated control (RAUDPC: 0.41). The weather prediction system resulted in 50% reduction in spray number, compared to scheduled applications in all seasons, however, using the weather station data, the number of timely sprays was reduced by 75% under a low disease pressure, reducing the risk of late blight.</div>