The present application provides a method for determining a plant protection treatment plan of an agricultural plant, the method carried out by a data processing unit (111), and the method comprising the steps of: obtaining (S110), by the data processing unit, plant observation data indicative for a current state of health of the agricultural plant or of a reference plant, obtaining (S120), by the data processing unit, weather data associated with a location at which the agricultural plant is cultivated, predicting (S130), by a computational model (113) executed by the data processing unit, based on the obtained observation data and the obtained weather data, a time-related disease probability of the agricultural plant, and determining (S140), by the computational model (113), based on at least the predicted disease probability, at least one plant protection treatment parameter to be included in the plant protection treatment plan.