In vitro evaluation of eco-friendly bioagents and botanical extracts against mulberry powdery mildew pathogen

Abstract

Mulberry powdery mildew caused by Phyllactinia corylea severely affects leaf quality and productivity, highlighting the need for safe and sustainable management options. The present investigation evaluated the efficacy of selected bioagents and botanical extracts against P. corylea by assessing inhibition of conidial germination under In vitro conditions. Among the bioagents tested at 0.1, 0.25 and 0.5 per cent concentrations, Trichoderma harzianum (Th-9) recorded the highest mean inhibition (63.15%), followed by Pseudomonas fluorescens (59.81%) and Trichoderma viride (53.70%). Bacillus subtilis showed comparatively lower inhibition (48.33%). Increasing concentration significantly enhanced antagonistic activity, with 0.5 per cent producing maximum suppression across treatments. Statistical analysis indicated significant differences among bioagents, concentrations and their interaction at the 1 per cent level. Botanical extracts evaluated at 5, 7.5 and 10 per cent concentrations showed pronounced variation in antifungal activity. Allium sativum (garlic) was the most effective, achieving complete inhibition (100%) at 10 per cent with a mean of 99.43 per cent. Allium cepa (onion) and Azadirachta indica (neem) also exhibited strong inhibition, recording mean values of 92.50 and 86.64 per cent, respectively. Zingiber officinale and Calotropis gigantea demonstrated moderate activity, whereas Morus alba extract showed minimal effect (14.67%). Higher concentrations consistently resulted in greater inhibition and the interaction between botanicals and concentrations was significant. The results indicate that T. harzianum, P. fluorescens, garlic and onion extracts possess substantial potential as eco-friendly alternatives for managing mulberry powdery mildew under laboratory conditions and merit further evaluation under field situations.