EFFECT OF CLOVE OIL ON PLANT PATHOGENIC BACTERIA AND BACTERIAL WILT OF TOMATO AND GERANIUM
Q. Huang, D.K. Lakshman
We determined the antibacterial activity of clove oil against seven different genera of plant pathogenic bacteria including Gram-negative Agrobacterium tumefaciens, Erwinia carotovora pv. carotovora, Pseudomonas syringae pv. syringae, Ralstonia solanacearum, and Xanthomonas campestris pv. pelargonii, as well as Gram-positive Rhodococcus fascians and Streptomyces spp. Both Gram-positive and Gram-negative bacteria tested were sensitive to clove oil, with R. solanacearum being the most sensitive one. Greenhouse experiments were therefore conducted to determine the effect of clove oil as a pre-plant soil fumigant on bacterial wilt of tomato and geranium caused by R. solanacearum. Seven days after treating R. solanacearum-infested plant growth medium (“soil”) with 5 ml of clove oil per kilogram of soil, populations of R. solanacearum were reduced to undetectable level, and none of the tomato and geranium plants transplanted into such soil developed wilt symptoms or harbored the bacterium. Our results suggest that clove oil has the potential to be an alternative control measure to combat bacterial wilt of tomato and geranium.