- The most devasting disease in apple trees is caused by the fungal pathogen Venturia inaequalis (Ascomycete).
The disease occurs worldwide in all apple growing areas and it is the first plant disease for which weather data based plant disease models have been developed and used in practical horticulture. Already Mills and Laplante confirmed in 1945 the relation between leaf wetness duration and temperature leading to apple scab infections.
- Further on models of Apple fire blight (Erwinia amylovora) based on Blossom Blight (also known as MaryBlight) and Cougar Blight widely used in Washington State in the United States are implemented. The models give an indication about the risk of a Fire Blight outbreak.
- The Codling moth (Cydia pomonella) model is based on the effective temperatures (between 10 and 32°C). The model figures out the first appearance after diapause and duration of the larvae instar 1 to 5 and well as the presence of adults in 5 levels (from flight activity with no egg-laying up to flight activity with strong egg-laying).
- The aphid propagation is mainly based on the temperature. Hours close to the optimum temperature and the availability of a food source will increase the propagation rate.
- For the Rain accumulation model the rainfall greater than 5mm is determined into 5 different grouping schedules.