Kontext

Apple scab is the disease that most impacts apple production in Girona. It is a polycyclic disease that starts at the end of winter. The primary inoculum, ascospore, comes from leaves on the ground affected by the disease in the previous autumn. Rain is the meteorological element that triggers the release of the spores and gives rise to the conditions necessary to germinate and infect the green tissues. The infections generate the first spots, from which new spores emerge to spread the disease. It can be kept under control by preventing primary infections from prospering. Accordingly, predictive models are used to issue warnings about conditions favourable to such infections. The RIMpro model is currently being used in Girona to predict the evolution of the primary inoculum. Fifteen to 20 fungicide treatments are applied per season, mainly to control scab disease. This number of fungicides could be substantially reduced by using physical barriers that prevent rainfall on the trees during the period when they are most sensitive to the disease.
The installation of anti-rain nets is being studied in various countries as an alternative to fungicide treatments (in France through the CTIFL’s ECOPHYTO programme; in Italy through the Edmund Mach Foundation, and in Canada amongst other countries). The materials used are mainly plastic raffia and plastic film, the same as those used to protect against cracking in plums. In our climate conditions these installations could be more effective, given that episodes of rain are less intense than Atlantic storms, which are often accompanied by strong winds that make it difficult to control the effects of rain.