Research Article Volume 37 No. 1 (March) 2023 Society for Biocontrol Advancement (Copyright 2000 SBA) Hymenopteran parasitoids in medicinal plants ecosystem..........16 Journal of Biological Control, 37(1): 32-45, 2023, DOI: 10.18311/jbc/2023/34206 ABSTRACT: 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 × 10 6 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. KEYWORDS: Ampelomyces quisqualis, compatibility, GC-MS, hyperparasitism, powdery mildew, Trichoderma asperellum (Article chronicle: Received: 26-01-2023; Revised: 22-03-2023; Accepted: 25-03-2023) Exploring eco-sensitive strategies for effective powdery mildew management in grapevines RANJAN KUMAR JENA 1* , I. YESU RAJA 1 , V. RAMAMOORTHY 2 , S. LAKSHMI NARAYANAN 3 , R. RENUKA 4 , A. SUBBIAH 5 , K. ERAIVAN ARUTKANI AIYANATHAN 1 , V. KARTHIK PANDI 5 and R. SIVADHARSHANAPRIYA 1 1 Department of Plant Pathology, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai – 625104, Tamil Nadu, India 2 Department of Plant Pathology, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Eachangkottai, Thanjavur – 614902, Tamil Nadu, India 3 Department of Plant Breeding and Genetics, 4 Department of Biotechnology, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai – 625104, Tamil Nadu, India 5 Grape Research Station, Anaimalayanpatty, Tamil Nadu Agricultural University, Theni – 625526, Tamil Nadu, India *Corresponding author E-mail: ranjan.ranjan.jena@gmail.com INTRODUCTION Grapevine (Vitis vinifera L.) is an important fruit and cash crop in India and its production is mainly obstructed by several biotic and abiotic stresses. Among the biotic stresses, particularly the powdery mildew disease is considered as the major concern, caused by Erysiphe necator Schwein (previously Uncinula necator (Schwein.) which is an obligate parasite belonging to the phylum Ascomycota (Vimala and Suriachandraselvan, 2009). Powdery mildew is a major disease affecting both cultivated and wild grapevine species worldwide, resulting in significant yield and economic losses (Gadoury et al., 2012; Dahivelkar et al., 2017). Disease severity varies from year to year, depending mostly on environmental conditions, the presence of inoculum (disease history), and the vulnerability of the vines. As a result, the steps that need to be taken to prevent losses, may differ from season to season (Dahivelkar et al., 2017). The disease affects the crop in all seasons, resulting in lower crop yields up to 40 per cent incurring significant economic losses (Siddappa et al., 2013). Many infected buds perished over the extreme winter resulting in yield losses in grapevines planted under cold agro-ecological environments. The pathogen can infect all green tissues of the plant, including leaves, shoots, flowers, and bunches, but flower and berry infections cause the most economic damage (Calonnec et al., 2004; Gadoury et al., 2012). Furthermore, the powdery mildew spreads to green shoots and causes red and brown lesions, and around bloom, grape bunches get affected, resulting in a drop in fruit as well as grape production. When haustoria enter into the epidermal cells of berries, the fruit die, or their skin shows scarring and spitting. Because of off-flavor and lack of freshness, infected grapes become unmarketable (Sadek et al., 2022). 32