Abstract:Phytophthora parasitica var. nicotianae is an important pathogenic fungus, but it is difficult to culture and produce zoosporangia on medium. Through experiments, the sesame agar medium, rye agar medium and oat agar medium can be used to culture Phytophthora parasitica var.nicotianae. Their growth speeds were 1.10, 0.78 and 0.86 cm per day respectively. The sesame agar and rye agar can be used to produce zoosporangia and their outputs of zoosporangia were 2.52×104, 2.07×104 zoosporangia/cm2 respectively, and their Release rates were 43.0% and 32.1% respectively. Tobaccos were inoculated by pouring and injecting different concentration zoospores suspension, disease indexes were directly related to the concentration and inoculation method.