Sugar beet ( Beta vulgaris var. saccharum, L.), a primary contributor to the worldwide sugar market, suffers severely from powdery mildew caused by Erysiphe betae , which reduces the photosynthetic efficiency and therewith yields. This study presents molecular docking analysis and randomized complete block design (RCBD) field trials with nutrient foliar sprays to identify disease management strategies. The interaction study in silico analysis using AutoDock Vina indicated tight-binding interactions of metal sulfates with the chitinase enzyme that degrades the fungal cell wall, where the metal sulfates MgSO ₄ (-4.03 kcal/mol) and ZnSO ₄ (-3.88 kcal/mol) exhibited significant inhibitory effects. Under natural infection conditions for field validation, a significant reduction in disease severity was observed using copper sulfate (81.56% reduction), comparable to a commercial fungicide. Foliar applications of nutrients improved agronomic traits. Root yield increased by 38% and total sugar yield by 90% compared to un-treated controls. Biochemical analysis revealed significantly enhanced defense responses, including elevated levels of total phenols (76% increase with Copper Sulphate), increased enzymatic activities (peroxidase up to 0.482 U/min/g and catalase up to 0.725 U/min/g), higher protein content (up to 11.29 mg/g), and enhanced proline accumulation (up to 3.54 mg/g) compared to controls. This study highlights the promise of nutrient foliar applications as an environmentally sustainable approach that could replace conventional fungicides to control powdery mildew in sugar beet production.

Cercospora leaf spot (CLS), caused by Cercospora beticola , is a severe threat to sugar beet ( Beta vulgaris ) production in Egypt’s Nile Delta and poses resistance and ecological problems to synthetic fungicides. This study investigates Alhagi maurorum (camelthorn), an endemic medicinal shrub of arid regions, and evaluates it as a sustainable plant-sourced biofungicide for integrated CLS management. Following molecular confirmation of C. beticola (PCR amplified actin gene, 959 bp; ITS region sequenced and deposited in GenBank under accession PX884367), A. maurorum ethanolic extract (GC–MS) profiling of the ethyl iso-allocholate (1.39%), squalene (7.81%), and methyl oleate (27.33%) was determined as the antifungal constituents from GC–MS profiling. Molecular docking highlighted ethyl iso-allocholate’s dual inhibition of CYP51 (− 8.4 kcal/mol) and CHS (− 6.5 kcal/mol), critical for fungal ergosterol biosynthesis and cell wall integrity. In vitro assays demonstrated complete fungal suppression at 10% extract concentration, mirroring the synthetic fungicide Score®. The efficacy of the extract in controlling disease (66.4–71.5% disease control), along with increased root yield (34.23 tons/fed) and sucrose purity (91.81–92.38%) in two-season field trials, was validated in CLS endemic Kafr EL Sheikh. The biochemical analyses of treated plants showed elevated antioxidant defenses, reflected in phenolics (184.43–186.73 mg/g) and superoxide dismutase (SOD: 122.10–123.77 U/g), to protect the plants against oxidative stress. As an eco-friendly alternative to synthetic fungicides, the extract has biodegradability, pharmacokinetic suitability, and multi-target action. By bridging phytochemistry, computational biology, and field agronomy, this work advances integrated, climate-resilient strategies for CLS management and underscores the potential of arid-adapted plants in sustainable agriculture.