Abstract: Aiming at developing biological control agents（BCAs）that can effectively suppress tomato
yellow leaf curl virus disease（TYLCD），this study investigated the biocontrol efficacy of the Pantoea
agglomerans strain Ljb-2 against TYLCD as well as its plant-growth-promoting effect under both
greenhouse and field conditions. Ljb-2 was originally isolated from the tomato environment. Applied to the
susceptible tomato variety Geruisi with root drenching in combination with foliar spray，it achieved the
significant biocontrol efficacy of 49.77% and 57.12% against TYLCD in the greenhouse and the field，
respectively，in spring 2012. At 60 d post transplantation in the field experiment in fall 2012，with the
same application method，Ljb-2 attained the biocontrol efficacy of 45.26% against TYLCD on Defenni （a tomato variety with moderate resistance to TYLCD）. Ljb-2 significant increased the contents of
leaf chlorophylls a，b，and a + b in the field，elevated tomato yield by 20.05%，leading to rises in the
contents of vitamin C，soluble sugar，titratable acid，and sugar-acid ratio in tomato fruit in the field in
fall 2012.

Key words: tomato, Tomato yellow leaf curl virus, biocontrol, Bemisia tabaci, Pantoe agglomerans