Objective The study was conducted to identify the pathogenic types of peanut pot rot in Guangdong and screen effective fungicides in order to provide a reference for the prevention and control of the disease in production.

Method The pure fungal cultures of fruit rot were isolated from the diseased peanut pods collected in fields by tissue isolation method, the pathogens were confirmed after the pathogenicity of the isolated strains were verified by back inoculation, and the pathogenic types were identified by cloning the strain's ITS sequence and phylogenetic analysis. The tissue samples were used to isolate fungi from rotted peanut pods. The pathogenicity of all isolates were tested based on Koch's rule, and then identified by ITS sequences analysis. The inhibition effect of 40% thiram WS, 98% hymexazol SP, 24% Jinggangmycin A AS, 10% difenoconazole WDG and 10% polyoxins WP against the peanut pod rot pathogens were determined by mycelia growth rate method. The EC₅₀ values of different fungicides were analysed.

Result Two pathogenic fungi were isolated from the peanut pod rot samples collected in Shaoguan. Both of them could cause peanut pod rot and even kernel rot after back inoculation. Phylogenetic analysis based on ITS sequences showed that the pathogens belonged to Fusarium oxyspourm and Fusarium solani. The inhibitory effect of 40% thiram WS was higher than other fungicides, and the EC₅₀ value on F. oxyspourm and F. solani were 0.001 mg/L and 0.021 mg/L, respectively. The EC₅₀ value of 98% hymexazol SP on two Fusairum strains were 0.296 mg/L and 0.217 mg/L, respectively. The EC₅₀ value of 24% Jinggangmycin A AS on two Fusairum strains were 20.575 mg/L and 11.185 mg/L, respectively. 10% difenoconazole WDG and 10% polyoxins WP had no inhibitory effect on the two Fusarium pathogen strains.

Conclusion Peanut pod rot in Guangdon is mainly caused by Fusarium co-infection, and F. solani is the main pathogen. The two strains F. oxyspourm and F. solani are both sensitive to thiram and hymexazol, which can be used as fungicides for the prevention in production.