First report of emerging fungal pathogens of Cordyceps militaris in Vietnam.

Cultivation of Cordyceps militaris, a valuable medicinal and edible fungus, has dramatically increased in Vietnam since 2010. During industrial production, parasitic white molds were found to infect the mycelia and fruiting bodies of C. militaris causing significant quality and yield losses. Two different fungal strains were obtained from the mycelia and fruiting bodies of C. militaris in Danang mushroom farms and were characterized by morphological and multiple DNA markers analysis. The sequence alignment of ITS, LSU and rpb2 markers revealed that the pathogens are related to the type species Lecanicillium coprophilum and Calcarisporium cordycipiticola with more than 99% sequence identities. The growth characteristics and pathogenic activities of the two isolated species on their host C. militaris were also investigated. The phylogenetic analysis based on the ITS sequences showed that L. coprophilum WF2611 is closer to its host C. militaris than C. cordycipiticola NT1504. To our knowledge, this is the first worldwide report of C. militaris infected by L. coprophilum which would be an useful information on prevention and control of the disease and be helpful for the industrial cultivation of C. militaris.