Occurrence and Identification of Tobacco Gray Spot Disease in Seedlings of Tobacco Floating System in Guizhou Province

A new tobacco disease named tobacco gray spot disease was found in Guizhou Province. After the separation and identification, the fungus was determined as Alternaria pluriseptata. The indoors test was conducted with four kinds of fungicides. The results showed that the best effectiveness was observed in the treatment of 70% triophanate-methyl WP, and the EC50 was 5.94 mg/L, while the other kinds of fungicides did not show any definite effect.