The identification,safety,and efficacy of the biocontrol fungi NX2A for Echinochloa crusgalli

【Objective】The strain NX2A was isolated from the leaves of susceptible Echinochloa crusgalli. Its taxonomic properties,safety for common farm crops,and pathogenic conditions for barnyard grass were studied to provide a theoretical basis for biological control of E. crusgalli.【Method】The strain was identified by morphological charaterization combined with ITS sequence analysis. The safety of NX2A on common crops like rice,rape,pepper,tomato and eggplant was determined via safety evaluation. L₉(3⁴) orthogonal experiment was used in the pathogenicity experiment of NX2A. Humidity,leaf stage,light and inoculation concentration was chosen as factors,disease index and the inhibition rate of fresh weight were as evaluation indexes.【Result】The pathogenic strain NX2A was identified as Curvularia lunata according to morphological identification and molecular identification. The spore suspension of NX2A had no obvious effects on rice,rape,pepper,eggplant and tomato. Plant leaves did not show the same or similar disease spots as barnyard grass. The results of pathogenicity experiment showed that the degree of the influence on disease index were in the order:light > inoculation concentration > humidity > leaf stage;the degree of the influence on fresh weight were in the order:inoculation concentration > light > humidity > leaf stage. The optimum treatment was A₃B₁C₃D₂,namely, 85% humidity, the 1-leaf stage, 12 h light, inoculation concentration was 5.0×10⁶ spores/mL.【Conclusion】C. lunata strain NX2A has a good prevention and control effect on barnyard grass,and is safe for rice,rape,pepper,eggplant,tomato,and has the potential of biological prevention and control of barnyard grass in paddy field.