Biological characteristics and pathogenicity of the biocontrol fungal strain NX1 for Echinochloa crusgalli

Abstract:

[Objective] Echinochloa crusgalli is one of the major noxious weeds in China’s farmlands. The long-term use of chemical herbicides has caused eco-environmental problems, such as the enhanced weed resistance and environmental pollution. Therefore, it is urgent to develop environment-friendly high-performance herbicides. [Methods] The strain NX1 was identified by tissue isolation, morphological observation, and molecular biological methods, and its pathogenicity and influencing factors were studied by multivariate statistical analysis. [Results] The strain was probably a new species of Curvularia. It can grow and produce spores at 25-30 and pH 5-11, with the highest sporulation quantity at pH 9 and 30. Although light did not affect the mycelial growth, continuous light was conducive to sporulation of the strain NX1. The strain NX1 can grow with different carbon and nitrogen sources, with the best utilization of corn meal and sodium nitrate. The laboratory biocontrol experiments showed that humidity, leaf age, light duration, and spore concentration significantly affected the pathogenicity of NX1 strain, among which humidity was the key factor. The crop safety test showed that the conidial suspension of the strain was safe to rice, rape, capsicum, and eggplant. [Conclusion] The strain NX1 has low requirements for environmental and nutritional conditions and is suitable for industrial production and field application. Therefore, it has the potential to be developed into a bioherbicide.