Context

The emergence of new pests and diseases disrupts the treatment strategy designed to achieve quality and productivity standards with low residue levels and low environmental impact. In this context, apple tree alternariosis, caused by the fungus Alternaria, is a new disease first described in Girona in 2013, and which has been gaining importance, to the point that it requires specific treatments to ensure the productivity of the orchards. This disease consists of foliar necroses that can lead to premature defoliation of the trees, but most critical is the effect on the fruit. Thus, alternariosis causes small, highly visible necrotic lesions that reduce the quality of the fruit and compromise its marketability. This disease can cause losses of between 10 and 40% of production depending on the year and the farm. The disease has been spreading to affect around 20% of commercial apple farms in the province of Girona in 2017. In the framework of the project, different farm management strategies have been assessed to reduce disease pressure, a treatment programme has been designed based on the most effective products and to maintain low residues, and a predictive model of the risk of alternariosis infection has been implemented to advise farmers on the positioning of treatments. All these improvements in the control of alternariosis developed in the project are already being used by the sector with a coverage of more than 90% of apple farms in the Girona area. The implementation of these improvements has led to better control of this disease.