Sistema de previsão da mancha-foliar-da-Gala em macieira, cultivar Gala

Gala-leaf-spot is the most important foliar disease of apple ‘Gala’ occurring in southern Brazilduring summer. It is caused by Colletotrichum spp. Nowadays, the control is done weekly by applying contact fungicides. A predictive system to detect the beginning of the disease based on the occurrence of favorable conditions (rainfall, temperature >15oC and wetness period >10 hours) was tested in order to indicate chemical application. The occurrence of three favorable continuous days was the best indicator as a predictive system to start sprayingwith fungicides in order to control this disease.