Antibacterial effect of Allium sativum and Ficus carica extracts on tomato bacterial pathogens

Bacterial pathogens are a serious problem on tomato plants. Amongst them, Pseudomonas syringae pv. tomato (Pst), Xanthomonas vesicatoria (Xv) and Clavibacter michiganensis subsp. michiganensis (Cmm), causal agents of bacterial speck, bacterial spot and bacterial canker, respectively, affect tomato production under greenhouse and field conditions. In in vitro tests with bacterial strains at a population density of 106 and 108 cfu ml−1, vegetal extracts from cloves of A. sativum and fruits of F. carica at concentrations of 1 and 30%, respectively, showed best effects at 106 cfu ml−1 bacterial concentration. In in vivo tests bacterial strains were tested at 105 cfu ml−1; A. sativum and F. carica extracts reduced disease incidence by 58 and 30%, and disease severity by 68 and 22%, respectively. Moreover, these vegetal extracts resulted in effective disease control of up to 65% (A. sativum) and 38% (F. carica) of that of the standard copper treatment. The antibacterial effects of A. sativum and F. carica extracts are useful for protecting tomato plants against Pst, Xv and Cmm in the greenhouse.