BIOSYNTHESIS of Zn nanoparticles(NPs) from 32 various plant samples were tested and subjected to 11 samples of ZnONPs from plant aqueous extracts, wherever, ZnNo3(1mmole) was used as precursor to synthesizing of ZnONPs. The UV-Vis spectral analysis of Morus nigra and Grevillea robusta plant leaves mix extracts (reaction mixture) were confirmed and showed performance of Zn NPs and exhibited as new sources for clean production and could be explored in various fields. During two tested seasons 2015/2016 and 2016/2017 and field conditions showed that, NPs of Ti followed by Zn caused to reducing of cercospora leaf spot (CLS) disease severity percentage of sugar beet plants and enhancement of TSS and sucrose contents, especially under high disease severity stress in season 2015/2016 compared to protected plants by eminent fungicide and control. NPs led to activation and recorded high enzymes activity values of enzymes of peroxidase up to 6 min and polyphenoloxidase up to 4 min estimation periods compared to control, so exhibited as mechanism in defense against CLS disease. Unseasonable weather conditions of temperature degrees, relative humidity percentage, wind velocity, pan evaporation and rain played an essential role in changement of CLS disease severity and susceptibility under field conditions during two tested seasons. The results recorded high percentages with first date of planting in September month in the first season of 2015/2016 with seven sugar beet genotypes than the second ones of October month and season of 2016/2017.