Under greenhouse and potted condition,inoculating the strong pathogenic isolate GY-31 of Alternaria alternata on tobacco seedlings of the tested varieties,Hongda and K326 at 7-leaf stage was conducted by applying mycelium block inoculation,spore spraying inoculation,spore suspension tampon inoculation,spore hanging drop inoculation,mycelium hanging drop inoculation,respectively,to select and develop a suitable method for inoculation of the brown spot pathogen in seedling stage of tobacco.The results show th...