Abstract: To investigate the antibacterial activity of garlic root exudates on Ralstonia solanacearum, the effect of garlic root exudates and their main components were tested against tobacco bacterial wilt (R. solanacearum) by inhibition zone method and pot trials. The results showed the inhibitory rate of 1 g/mL crude garlic root exudate extract was higher than those of the other extracts, with the inhibitory rate of 53.67%. The inhibitory effects of the four components, from the strongest to the weakest, were as follows: 2,6-diisopropylphenol＞diallyl disulfide ＞2,6-di-tert-butyl-p-cresol＞dibutyl phthalate. 2,6-diisopropylphenol had the greatest inhibitory effect, with the inhibitory rates of 99.66% and 100.00% at 1 mmol/L and 5 mmol/L, respectively. 2,6-diisopropylphenol had good control effects in the pot trials, with the efficacies of 34.79% and 31.35% at 1 mmol/L and 5 mmol/L at 7 and 14 days after inoculation, respectively. Therefore, the garlic root exudates and its components had significant inhibitory effects against tobacco bacterial wilt. The above results revealed the control mechanism of garlic as a rotation or intercropping crop on tobacco bacterial wilt, and the potential of garlic root exudates and 2,6-diisopropylphenol as a control agent for bacterial wilt in tobacco fields.

Key words: tobacco, garlic root exudate, Ralstonia solanacearum, control effect