The evaluation of the effectiveness of flax oil; mayonnaise oil formulation; AgNPs@oil and CuNPs@oil nanoemulsions against Alternaria solani that infects tomato plant. Flax oil was formulated as a mayonnaise formulation (43%). The local formulation overrrun all of the laboratory investigations of mayonnaise oil formulation. Preparation of flax oil was AgNPs@oil and CuNPs@oil nanoemulsions. Using transmission electron microscope (TEM) to detect the size, shape and structure in both AgNPs@oil and CuNPs@oil nano-emulsions was conducted. In vitro tests, CuNPs@oil nanoemulsion gave the complete inhibition in mycelium growth occurred for A. solani at concentration of 200 ppm. Under the greenhouse, azoxystrobin 25% SC was the best, which reduced disease severity at 7, 14 and 21 days after transplanting followed by CuNPs@oil; AgNPs@oil, mayonnaise oil formulation and flax oil. The CuNPs@oil and AgNPs@oil showed high level of peroxidase (PO) and polyphenoloxidase (PPO) compared with the control. Therefore, it can be concluded that CuNPs@oil, AgNPs@oil nanoemulsions, mayonnaise oil formulation and flax oil might have antifungal activity against A. solani.