Exploring eco-sensitive strategies for effective powdery mildew management in grapevines

Grapevine powdery mildew is one of the most important plant diseases widely affecting crops in many countries. The main aim of the present study was to use Ampelomyces quisqualis isolates to suppress the powdery mildew of grapes under field conditions. The findings revealed a strong correlation between the mycoparasite, Ampelomyces quisqualis and the grape powdery mildew pathogens, suggesting its potential for effective control. The results revealed that a single spray of A. quisqualis @ 2.0 per cent (MDU1) succeeded by two sprays of Trichoderma asperellum @ 2.0 per cent (Tasp,7) were found to be effective against Erysiphe necator. In addition, liquid formulation of A. quisqualis isolate MDU1 (2% w/v) as a foliar spray at 2% containing 2 × 106 spores ml-1 the during initial occurrence of the disease up to three sprayings at 15 days interval was found to be best. Thus, a liquid formulation of A. quisqualis isolate MDU1 proved effective in managing grapes powdery mildew disease under field conditions. The rDNA ITS region of A. quisqualis isolates was analyzed at the molecular level, and the resulting sequences were subjected to GC-MS analysis. The secondary metabolite identification using GC-MS revealed the presence of antimicrobial compounds, including squalene with the highest peak of 4.643 percent, octadecanoic acid with 3.862 percent, tetradecanoic acid with 3.600 percent, and 9,12-octadecadienoic acid (Z,Z) with 1.451 percent. These bioactive compounds revealed by GC-MS analysis in crude extracts of A. quisqualis had a stronger antifungal activity against E. necator.