The authors tested the efficacy of two salt nanoparticles (NPs), namely, copper dioxide (CuO) and tri-calcium phosphate [Ca 3 (PO 4 ) 2 ] to induce resistance in green bean pods against grey mould and white rot diseases caused by Botrytis cinerea and Sclerotinia sclerotiorum , respectively. High amounts of phytoalexins, kievitone, coumestrol, phaseollidin, 6-ά-hydroxyphaseollin, and phaseollin, were detected in naturally infected and artificially inoculated green bean pods in response to the tested NPs. Green bean plants treated in the field with CuO and Ca 3 (PO 4 ) 2 NPs had the highest mRNA quantity of all the studied defence genes, receptor-like kinase ( PvRK20 ), pathogenesis-related protein ( PR1 ), 1,3-β-D-glucanase ( pvgluc ), polygalacturonase inhibitor protein ( PvGIP ), and alpha-dioxygenase ( a-DOX ) than that of the control group. CuO NPs followed by Ca 3 (PO 4 ) 2 NPs at 0.15 mg ml −1 were