Abstract: This study was conducted to evaluate the efficacy of foliar liquid Proteck MgS+ (manufactured with nanotechnology, imported from the Land of the Palm Company for Agricultural Services) in reducing the incidence of yellow rust disease caused by Puccinia striiformis f. sp tritici in two wheat cultivars Tamuz-2 and AL-8/70. The Proteck MgS+ caused significant reduction in of incidence as compared with control. The low incidence with 3 ml l-1 concentration being 1.23 and 0.13 compared with 8.84 and 9.02 in control for the two cultivars Tamuz-2 and AL-8/70 respectively. The reduction in disease incidence was associated with increases in peroxidase (PO) and phenylalanine ammonia-Lyase (PAL) enzymes activity and increase in phenolic compound accumulation The MgS+ hold promise in management of yellow rust disease management on wheat in Iraq.