Reduced Tomato Bacterial Wilt by Ferrous Chloride Application

Exogenous ferrous chloride (FeCl2) suppressed in vitro growth of Ralstonia pseudosolanacearum, causing bacteria for tomato bacterial wilt. More than 50 µM of FeCl2 reduced the in vitro bacterial growth in dose-dependent manners. Two to 200 µM of FeCl2 did not affect the fresh weight of detached tomato leaves at 3 and 5 days after the petiole dipping without the bacterial inoculation. The bacterial wilt of the detached tomato leaves was evaluated by inoculating two different inoculum densities of R. pseudosolanacearum (105 and 107 cfu/ml) in the presence of FeCl2. Bacterial wilt in the detached leaves by 105 cfu/ml was efficiently attenuated by 10–200 µM of FeCl2 at 3 and 5 days post-inoculation (dpi), but bacterial wilt by 107 cfu/ml was only reduced by 200 µM of FeCl2 at 3 and 5 dpi. These results suggest that iron nutrients can be included in the integrated disease management of tomato bacterial wilt.