The impact of specific environmentally friendly resistances on the barley powdery mildew disease under the effects of Climate Change

This study evaluates the effectiveness of environmentally friendly treatments in managing barley powdery mildew caused by Blumeria graminis f. sp. hordei under greenhouse and field conditions during the 2024 and 2025 growing seasons at the Agricultural Research Centre (ARC), Giza, Egypt. Five treatments—biocide Blight Stop (Trichoderma harzianum), three natural plant oils (neem, thyme, and tea tree oil), and the fungicide Farmazole—were assessed for their ability to reduce disease severity, delay incubation and latent periods, and improve yield‑related traits. Results from both experimental seasons demonstrated that all eco‑friendly treatments significantly reduced disease severity, area under the disease progress curve (AUDPC), and average coefficient of infection (ACI) compared with the untreated control. Farmazole exhibited the highest efficacy, followed closely by Blight Stop, while thyme oil consistently showed the least effectiveness. Improvements in yield parameters, including 1000‑grain weight and grain yield per plot, were recorded in all treatments. Additionally, total chlorophyll and carotenoid contents increased significantly, reflecting enhanced physiological performance in treated plants. This research highlights the potential of integrating plant‑derived oils and biological control agents as sustainable, safe, and effective alternatives to chemical fungicides for managing powdery mildew. The findings support their role in reducing chemical residues, mitigating environmental impact, and contributing to sustainable barley production systems.