Evidence of white mold disease caused by Neonectria candida on Morchella importuna

Morels (Morchella sp. pl.) are valuable mushrooms, and their applications in the pharmaceutical and food industries has steadily increased in China.White mold disease is a common and severe disease in the culturing of morels, which is mainly manifested as white villous mycelial infection on the fruiting bodies of these mushrooms. However, the causal agent is not yet known. Therefore, this study aims to identify, at the species level, the causal pathogen of this disease via morphological and molecular methods and then to confirm its pathogenicity through Koch's postulates. The pathogen was identified as Neonectria candida. Healthy ascocarps were inoculated with N. candida, which produced the initial disease symptoms with white mold appearing at the inoculation sites. The same pathogen was then isolated again from diseased ascocarps. To our knowledge, this is the first report of Morchella importuna ascocarps with white mold disease caused by N. candida in China. Moreover, this report will inform the establishment of sustainable management strategies for white mold disease in morels.