The causal microorganisms of Panax notoginseng root rot disease.
Objective: Panax notoginseng, cultivated in Yunnan, China, is an important medicinal herb. Rot root disease is the most serious problem limiting the production of the herb. Method: Panax notoginseng root rot disease was surveyed and sampled in the field. The pathogens of the root rot was isolated and identified. Pathogenicity tests in vitro and in field were carried out. Result: A survey on the disease indicated that the symptoms of the disease are expressed as dry chap rot, medullary tissue rot, slowly yellow rot, stem base dry rot, suddenly wilt rot and wet rot. Among them, slowly yellow rot and suddenly wilt wet rot were the most popular ones. Dry chap rot, medullary tissue rot and stem base dry rot are new records for symptoms of the disease. Cylindrocarpon destructans, C. didymum, Fusarium solani, Phytophthora cactorum, Phoma herbarum, Monilia sp., Verticillium sp., Trichoderma sp., Rhizoctonia solani were involved in the disease. In vitro pathogenicity tests demonstrated that C. destructans, C. didymum, P. cactorum, P. herbarum and R. solani could result in the disease at different levels. Field inoculation tests showed that P. cactorum and P. herbarum were the most pathogenic fungi, leading to disease incidences of 48.4% and 50.0%, respectively. Conclusion: However, C. destructans and C. didymum were considered as two of the most important fungi causing Panax notoginseng root-rot diseases because of their wide distribution, high frequency of isolation, and close relationship with dominant symptom.