ABSTRACT
Data available in the literature were used to develop a model to forecast onion downy mildew caused by Peronospora destructor. The developed model is based on weather conditions favorable to the infectious process, according to temperature and leaf wetness duration. The interaction that represents the two factors on the probability of infection was obtained. Using Excel sheet, leaf wetness duration was calculated to obtain different probabilities of infection by pathogens at different temperatures. These data were employed to create a table that can be used in computer programming to record leaf wetness duration and average temperature and, automatically, the daily value of probability of infection occurrence. The model will be validated in field experiments under natural infection in Rio do Sul, Santa Catarina State, Brazil.
Keywords
Allium cepa; Peronospora destructor; plant disease forecasting