Study on the Control Efficacy of Different Fungal Agents against Tobacco Viral Diseases

Fungal elicitors could induce plant systemic resistance and resistance against plant virus. The antiviral activities of Fusarium oxysporum, Physalospora piricola, Fusarium graminearum, and soil fungus strains ESF-6, XFPF-6, C1, XFSF-8 and Phytophthorasp.were studied.Fungi were cultured by liquid fermentation,the fermentation broth were collected and sprayed on leaves of tobacco plants.The antiviral effects of the fungi were determinedvia field experiments. The results showed that all eight fungal agents could control tobacco virus diseases. The controlling efficiency of strain ESF-6 was the highest, 83.8% at the peak of disease incidence. The controllingefficiency of XFPF-6 was60%, and was stable during the whole tobacco growth period. The controlling efficiency of F. graminearum and P. piricola were also high, being 64.8% and 73.7%, respectively. Except for strain C1, control efficiency of the other seven fungal agents were all higher than that of moroxydine hyrochloride. These fungi can be used in developing antiviral fungal agents. Based on 18s rRNA sequences of fungi and morphology observation, strain ESF-6 was identified as Aspergillus sp., and strain XFSF-8 identified as Penicillium sp.