Abstract:

The study aims to determine the physiological races and mating types of tobacco black shank disease in Guiyang City, in order to establish a foundation for the treatment of black shank disease in the area. The pathogen causing black shank disease was isolated and purified from tobacco plants affected in the tobacco-growing region of Guiyang City, Guizhou Province. The isolated strains were subjected to molecular identification, mating type determination, physiological race identification, and sensitivity testing to chemical agents in vitro. Field trials were conducted to evaluate the efficacy of different agents in controlling black shank disease in tobacco plants. Samples of tobacco black shank disease were collected from 69 plants in 5 different tobacco-growing areas in Guiyang City. After isolation and identification, 48 strains of Phytophthora nicotianae were obtained. All 5 representative strains belonged to the A1 mating type, with 2 strains being of physiological race 0 and 3 strains being of physiological race 1. The toxicity test and field efficacy test of the chemical agents in the dish showed that the inhibitory effect of ethylicin·copper oleate against P. nicotianae was better than mancozeb, dimethomorph, metalaxyl-M, fluopicolide·propamocab hydrochloride and chitosan.

Key words: tobacco black shank, physiological race, mating type, fungicide screening, control effect