Colletotrichum salicis , an Important but Overlooked Pathogen of Willows in the Czech Republic

The invasive fungal pathogen Colletotrichum salicis , the causal agent of willow anthracnose and shoot blight, was first recorded to cause massive damage to willow in the Czech Republic in 2002 on Salix euxina . Since then, the pathogen has been repeatedly documented also in other willow species (e.g., S. caprea , S. cinerea , S. viminalis ) with the most severe damage occurring on Salix matsudana ‘Tortuosa’, which appears to be highly susceptible. Typical symptoms on infected hosts include necrotic lesions on young shoots, shoot dieback, premature defoliation and crown dieback, especially in their lower part. Disease occurrence and severity are strongly associated with inversion‐prone sites and with cold, rainy weather during spring, which promotes prolonged tissue wetness and delayed maturation of current‐year shoots. Based on currently available records, C. salicis represents an underestimated threat to willow stands in the Czech Republic. This short communication documents its occurrence, host range, impact and basic information about its ecology and disease epidemiology and highlights the need for systematic monitoring and precise diagnosis to better assess its current distribution and potential ecological consequences. The increase in the importance of this species may be associated with recent spread of willow species, especially in riparian vegetation, where ash, elm and alder have retreated due to damage by invasive pathogens.