Bacillus subtilis can suppress Meloidogyne spp. in soil and roots of tropical fruit trees

ABSTRACT Bacillus subtilis has been recognized as an efficient biological controller against Meloidogyne spp. in roots of annual crops, but its efficiency in fruit tree roots remains poorly known. This study assessed the effect of the new B. subtilis strain (PRBS-1) on the suppression of Meloidogyne spp. in the soil and roots of banana, guava, and fig in field conditions naturally infested with the nematode. Thus, B. subtilis suspension was inoculated directly to the soil surface around the stem of these fruit trees at the dose of 1 L·ha-1 (100 L of water), while plants not treated were used as control. The number of Meloidogyne spp. in the soil and roots was assessed before and after (three months) the application. The samples were collected from the central plants of the plot, at 20 cm from the stem and 5–30 cm soil layer of depth. B. subtilis promoted a decrease in the population of Meloidogyne spp. in soil and roots of fruit trees after three months of application, being more effective in decreasing Meloidogyne spp. in roots than soil. The decrease in Meloidogyne spp. in roots with the application of B. subtilis ranged from 70.1 to 86.3% in the roots of guava and fig, respectively. In the soil, the application B. subtilis decreased from 29.8 to 73.4% of the population of Meloidogyne spp. Therefore, this study showed that B. subtilis has potential as a biological control agent against Meloidogyne spp., in banana, guava, and fig roots.