ISOLATION AND CHARACTERIZATION OF BIOCONTROL BACTERIUM TL6 FOR PEANUT EARLY LEAF SPOT.

Peanut early leaf spot caused by Passalora arachidicola is serious fungal disease, which occurs in all production areas in China. Chemical control is the main method to prevent this disease. Nevertheless, it is easy to cause resistance, resurgence, residue problem (3R). Therefore, biological control is becoming the research hotspot for peanut early leaf spot control. 60 healthy peanut leaves were collected from major peanut production areas and were got for potential bacterial isolates. A total of 465 isolates were obtained. 22 strains showed differing levels of resistance against P. arachidicola. Among the antagonistic isolates, strain TL6 showed strongest inhibitory activity. It was identified as Bacillus amyloliquefaciens based on morphological characteristics, physiological and biochemical reactions as well as comparative analysis of its 16S rDNA sequence. The field control effect was above 69.17% after spraying the fermentation liquid of strain TL6. The field control effect of the strain TL6 fermentation liquid diluted 200 times and including the addition of 500 g/L carbendazim diluted 1000 times inhibited P. arachidicola by 81.33%. The combination of strain TL6 and carbendazim had a significant synergistic effect. Overall, strain TL6 showed promising potential commercial development and application in controlling peanut early leaf spot disease. [ABSTRACT FROM AUTHOR]