Crown and root rot disease caused by Fusarium oxysporum f.sp. radicis-lycopersici (FORL) is a destructive pathogen on the seedling and mature tomato (Lycopersicon esculentum Mill) plants in greenhouses of Turkey. The synergistic effect of abiotic stress (100 mM NaCl) by known chemical defense inducers DL-β-Aminobutryric acid (BABA) to FORL was tested on tomato plants. The roots of plants were immersed into 125, and 500 µg mL-1 BABA or foliages of plants were separately sprayed by BABA (125, 500 µg mL-1) before the plants were inoculated with fungal spore suspension by day 1 post treatment. Furthermore, in another study conducted on only by BABA and abiotic stress (foliar spray) resulted in remarkable plant disease resistance if the plants were detached into BABA (125 µg mL-1) solution. This combination caused a positive effect on plants, which was comparable with the plants detached into the highest BABA concentration at 500 µg mL-1. Disease severity of plants on which abiotic stress and BABA combination used was also lower than the control and BABA sprayed at 500 µg mL-1 to nontreated (control) plants alone until the 20th day post inoculation. Therefore, synergistic effect by salt stress and BABA can be suggested for plant resistance to FORL.