Eco-friendly management of cercospora leaf spot disease in sugar beet using ZnO and MgO nanoparticles

Cercospora leaf spot, caused by Cercospora beticola, is the most destructive disease of sugar beet. This study evaluated zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles (NPs) as sustainable alternatives to chemical fungicides.

In vitro experiments, at a concentration of 90 ppm, the fungal inhibition rate of MgO NPs reached 58.33%, higher than the 52.08% recorded for ZnO NPs. SEM observations confirmed that both types of nanoparticles caused severe distortion and deformation of the mycelium of the tested fungi. However, under greenhouse and field conditions, ZnO NPs provided superior disease control, reducing disease severity by up to 50.92%. Both also raised crop phenolic content and boosted PO, PPO, and PAL enzyme activity, peaking 6 days post-treatment. Treated crops showed higher root yield and sucrose and less unwanted sugar than untreated controls.

Both ZnO and MgO nanoparticles represent promising alternatives to conventional fungicides for the management sugar beet leaf spot disease. Although MgO NPs were more effective in vitro, ZnO NPs were more effective in greenhouse and field conditions. They can also enhance sugar beets' defense responses, root yield, and sucrose content, and can be incorporated into the sustainable plan for integrated sugar beet disease management.