Emerging Colletotrichum Diseases on Apple in European Orchards: Challenges and Perspectives

In recent years, infections caused by Colletotrichum spp. have shown a concerning increase in European apple orchards, with Apple Bitter Rot (ABR) and Glomerella Leaf Spot (GLS) emerging as significant threats. Previously prevalent in the Americas and Asia, these diseases are now spreading into temperate European regions, driven by climate change that favors the establishment of tropical species such as C. fructicola, C. chrysophilum, C. grossum, C. siamense. Accurate identification of these pathogens is challenged by their genetic and biological diversity, necessitating multi-locus phylogenetic analyses and advanced molecular techniques. This article reviews the infection cycles, pathogenic strategies, and current management challenges, including increasing fungicide resistance. It highlights the urgent need for integrated control approaches combining agronomic practices, biological treatments, and rapid diagnostic tools to mitigate disease impact and protect European apple production.