Cas de suie de l'érable et de chancre du peuplier dans le canton de Genève

Abstract

In summer 2014, a case of sooty bark disease caused by Cryptostroma corticale on an individual field maple (Acer campestre) and two cases of poplar canker due to Cytospora chrysosperma on Populus x euramericana were identified genetically for the first time on the territory of the Canton of Geneva. In both cases, the trees presented signs of very advanced dieback, accompanied by specific symptoms such as bark peeling and sooty plaques for the maple, and loose twisted bark layers and black colouring of the wood in structural branches of the poplars. Sampling was carried out in the symptomatic areas and components of the fungal flora were isolated in pure cultures in order to identify any pathogenic fungi. The molecular analysis of the rDNA internal transcribed spacer (ITS) sequences made it possible to identify precisely all pure isolates obtained. The results showed a majority presence of C. corticale in the maple tree, and of C. chrysosperma in the two poplars. Both these fungi are little known in Switzerland and Europe, and their presence is maybe associated with changes in the climate.