| 【Objective】The study was conducted to identify the pathogen causing Nigrospora blight on sugarcane,
analyze the pathogen biological characteristics, design detection primers for the pathogen Nigrospora sphaerica, screen out
fungicides which can effectively inhibit the pathogen N. sphaerica, and to provide guidance on field control of Nigrospora
blight on sugarcane.【Method】The pathogen of Nigrospora blight on diseased sugarcane leaves collected from Panyu
District, Guangzhou City, Guangdong Province was purified and cultured by tissue separation method. After 5 days of
culture, the morphology of mycelium and spores was observed by using an optical microscope. The fungi were determined
for pathogenicity, and the pathogenic strains were amplified and sequenced by PCR with the primers ITS1/ITS4; then,
the software MRGA 7.0 was used to construct a phylogenetic tree based on ITS sequence with the maximum likelihood method and sequence-specific detection primers Ng1F/Ng1R and Ng2F/Ng2R were designed according to the obtained ITS
sequence. The indoor control effects of 7 different fungicides on N.sphaerica were screened by the mycelium growth rate
method. The antibacterial effect of N.sphaerica, which is the pathogen of Nigrospora leaf blight on sugarcane, was screened.
【Result】Through the study on morphological and molecular identification as well as biological characteristics, it was
determined that the pathogen causing Nigrospora blight on sugarcane was N.sphaerica, which had the fastest colony growth
rate at the temperature of 25 ℃ and pH of 7. The PCR method confirmed that the primers Ng1F/Ng1R could be used to detect
the pathogen of sugarcane Nigrosporium blight. The results of the indoor antibacterial test showed that 0.16 mg/L of Prochloraz
and 2.4 mg/L of Sporgon had the best antibacterial effect on N. sphaerica, and the antibacterial effect could reach over 93%.
【Conclusion】The pathogen causing sugarcane seed-borne disease Nigrospora blight is N.sphaerica. Ng1F/Ng1R can be
used to detect the pathogen of N.sphaerica. Prochloraz and Sporgon agents can be used as the optimal fungicides for N.sphaerica
in the field or seedling detoxification treatment agent. |
