Pathogen identification of tobacco rhizomatic diseases in tobacco growing areas of Henan Province

In order to clarify the occurrence, distribution and pathogen species of tobacco rhizomatic diseases, the rhizomatic diseases in 11 tobacco growing areas in Henan Province were investigated. A total of 644 typical disease samples were collected to identify the pathogens through morphological characteristics, molecular identification and pathogenicity test. The results showed that the average detection rate of Fusarium spp. was 52.60%, followed by those of Phytophthora nicotianae and Rhizoctonia solani at 27.94% and 12.52% respectively. Tobacco root rot, black shank and sore shin caused by them were the main rhizomatic diseases in Henan tobacco growing areas. Tobacco stalk blight caused by Phomopsis sp. was a new tobacco disease with an increasing incidence in central and western tobacco growing areas of Henan in recent years. Cultivated under the condition of 25 ℃, Phomopsis sp. could produce small conidia, which could infect stalks and leaves of tobacco plants, while the pathogenicities of different pathogenic strains differed significantly.