Abstract: 【Objective】Early leaf spot disease and web blotch disease are the most serious disease in peanuts. The symptoms of these two diseases always occur on the same plant in the late growth stage of the peanut, and cause serious yield losses in peanut production. The objectives of this study are to evaluate the factors that influence the infection probability and latent period of Cercospora arachidicola and Phoma arachidicola after mixed infection on peanuts, investigate the interactions between disease and host plants, and provide a basis for formulating comprehensive control of more diseases and pests on the same host.【Method】C. arachidicola and P. arachidicola were inoculated on susceptible cultivar, Baisha1016. In the field, different plant growth stages, inoculum concentration and leaf wetness period were constructed. The influences of the mixed infection of C. arachidicola and P. arachidicola on the infection probability and latent period were analyzed.【Result】When C. arachidicola and P. arachidicola were inoculated alone, the infection probability of both pathogens were increased with the extension of the growth stage. Specifically, the infection probability for the different growth stage of peanut was: early flowering stage C. arachidicola and P. arachidicola were inoculated alone at different stages, there were significant differences between the latent period of the two pathogens. In the early flowering stage and late flowering stage, the latent period of C. arachidicola was 20 d, but in the flowering stage, the latent period of C. arachidicola was 16 d; in the early flowering stage, the latent period of P. arachidicola was 10 d, however, in the flowering stage and the late flowering stage, the latent period of P. arachidicola was 7 d. The latent period could be affected by leaf age and the degree of senescence, it was longer in the early growth stage than the late growth period, but had little significant correlation with temperature and humidity. Mixed inoculation of the two pathogens prolonged the latent period. In the early flowering stage, the latent period for C. arachidicola and P. arachidicola increased for 2 d and 5 d, compared to the pathogens inoculated alone. And in the flowering stage and the late flowering stage, the latent period for C. arachidicola and P. arachidicola increased for 4 d and 2 d, respectively, but the latent period of P. arachidicola had no obvious change, all were 7 d.【Conclusion】When the C. arachidicola and P. arachidicola were inoculated individually, the infection probability of the two pathogens increased with the extension of the growth stage and leaf wetness duration and the increase in inoculation concentration. However, when the two pathogens were inoculated simultaneously, the infection probability was decreased and the latent period was prolonged. In addition to the influence of the interactions between the pathogen and host, the latent period of C. arachidicola and P. arachidicola could be affected by leaf age and the degree of senescence, but had little significant correlation with temperature and humidity.

Key words: Cercospora arachidicola, Phoma arachidicola, infection probability, latent period, mixed infection