Symptoms of sclerotinia stem rot of Ligusticum chuanxiong were observed and the causal agent of the disease was identified.The results showed that the symptoms of this disease began with the formation of dark brown hygrophanous splotch on the basal leaves,followed by the appearance of dark brown circular spot on the basal stem.Finally,the whole plant stoped growing and died.White mycelium and/or sclerotia were formed under moisturized conditions.On PDA medium,the pathogen of this disease formed brown sclerotia with various shapes and 2-5 mm in diameter.The diameter of apothecia was 0.3-0.8 cm and the length of stipes was 2-8 cm.Asci were columniform in shape and(100-135)×9 μm in size,each containing 8 ascospores sized by(6-12) μm×(3-7) μm.No asexual spore formation was observed.Based on the morphological characteristics and the sequence of ribosomal DNA-ITS,the pathogen was identified as Sclerotinia sclerotiorum(Lib.) de Bary.
