Colletotrichumspp. causing anthracnose on ornamental plants in northern Italy

Species ofColletotrichumare considered among the most important plant pathogens, saprobes and endophytes on a wide range of ornamentals, fruits and vegetables. SeveralColletotrichumspecies have been reported in nurseries and public or private gardens in northern Italy. In this study, the occurrence, diversity and pathogenicity ofColletotrichumspp. associated with several ornamental hosts was explored. Survey were carried out during the 2013-2019 period in Piedmont, Italy. A total of 22Colletotrichumisolates were collected from symptomatic leaves and stems of twoCampanulaspp.,Ceanothus thyrsiflorus,Coreopsis lanceolata,Cyclamen persicum,Hydrangea paniculata,Liquidambar styraciflua,Mahonia aquifoliumandRhyncospermum jasminoides. A multi-locus phylogeny was established based on the basis of three genomic loci (gapdh,actandtub2). The pathogenicity of selected, representative isolates was tested.Colletotrichumisolates were identified as members of four important species complexes: Acutatum,Gloeosporioides,DematiumandDestructivum.Colletotrichum fioriniae,C. nymphaeaeandC. fuscumwere found in association with leaf lesions ofMahonia aquifolium,Campanula rapunculoidesandCoreopsis lanceolata, respectively.Colletotrichum lineola,C. grossumandC. cigarrowere isolated fromCampanula trachelium,Rhyncospermum jasminoidesandLiquidambar styraciflua, respectively.Colletotrichum fructicolawas found to be responsible of anthracnose ofCeanothus thyrsiflorus,Hydrangea paniculata,Cyclamen persicumandLiquidambar styraciflua. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in private gardens and nurseries. The present study improves our understanding ofColletotrichumspp. associated with different ornamental hosts and provides useful information for an effective disease management programme.

Automated summary

Species of Colletotrichum are important plant pathogens, saprobes and endophytes on various ornamentals, fruits and vegetables. This study in Piedmont, Italy, explored the occurrence, diversity and pathogenicity of Colletotrichum spp. associated with different ornamental hosts, identifying key species complexes and their association with specific plant diseases. The findings provide valuable information for disease management of these ornamental plants.