~ 3022 ~ International Journal of Chemical Studies 2021; 9(1): 3022-3028 P-ISSN: 2349–8528 E-ISSN: 2321–4902 www.chemijournal.com IJCS 2021; 9(1): 3022-3028 © 2021 IJCS Received: 18-10-2020 Accepted: 29-12-2020 Rajkumar Debsharma Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India Saidul Islam 1. Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India 2. Nadia Krishi Vigyan Kendra, Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia, West Bengal, India Debanjana Debnath Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India Sunanda Chakraborty Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India Sunita Mahapatra Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India Corresponding Author: Sunita Mahapatra Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India Efficacy study of some botanical oils against spot blotch disease ( Bipolaris sorokiniana ) of wheat under In-vitro condition Rajkumar Debsharma, Saidul Islam, Debanjana Debnath, Sunanda Chakraborty and Sunita Mahapatra DOI: https://doi.org/10.22271/chemi.2021.v9.i1ap.11690 Abstract Bipolaris Sorokiniana (Teleomorph Cochliobolus sativus) is the causal agent of spot blotch of wheat. The fungus is one of the most important foliar diseases for wheat growing areas and causes significant yield losses particularly in South Asia’s intensive “irrigated wheat-rice” production system. In West Bengal as well as all Eastern India, one of the most concerning disease is spot blotch of wheat. Intensive efforts in many countries are now underway to develop effective management strategies. However, current practices mostly rely on chemical fungicides which are costly as well as environmentally harmful. Naturally available plant protectants, such as essential oils (EOs) which show antimicrobial properties, have low mammalian toxicity and are environment-friendly, could be used as alternatives for chemical fungicides. Five botanical oils [Ginger oil, Eucalyptus oil, Clove oil, Til oil and Neem oil] and one fungicide (Mancozeb 75% WP) were tested against the Bipolaris sorokiniana causing spot blotch of wheat, at five different concentrations: 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, and 3000 ppm. Among them, Clove oil exhibited strongest fungal toxicity followed by Ginger oil, Eucalyptus oil, Til oil and Neem oil, at all concentrations. The fungistatic ability increased with an increase in concentration of the plant protectants. All the essential oils showed fungistatic activity while maximum inhibition of the pathogen was observed at a concentration of 3000 ppm. Keywords: Spot blotch, essential oils, Bipolaris sorokiniana, in-vitro, wheat 1. Introduction Wheat (Triticum aestivum L.), belonging to family Graminaceae is a dominant cereal crop and staple food of millions of people in the world. In the year of 2018-19, wheat production in India reached 101.20 million tonnes which marked an all-time highest crop productivity of 3424 kg/ha (Annual Progress Report, 2018-19) [1] . The importance of foliar blight must be expressed in terms of yield losses but the estimate widely varied according to variety (Nema and Joshi, 1971) [21] . With every one percent increase in disease severity there is a significant crop loss caused by spot blotch of wheat (Devi et al., 2018) [6] . Foliar blight is a serious problem in the North Eastern region, while being significantly destructive throughout the wheat growing belts of the country (Tamang et al, 2020) [30] . It is apparent from their development that foliar blight may pose a threat to wheat in the near future. Bipolaris Sorokiniana (Teleomorph: Cochliobolus sativus) is the causal agent of spot blotch or foliar blight of wheat. The fungus is one of the most important foliar disease constraints for wheat crops growing in warmer areas and causes significant yield losses. High temperature and high relative humidity favour the outbreak of the disease, particularly in South Asia’s intensive “irrigated wheat-rice” production system. In West Bengal as well as all Eastern India one of the major fungal diseases is foliar blight caused by Bipolaris sorokiniana and Alternaria triticina, which may attack singly or together causing yield loss exceeding 60% (Prabhu and Singh, 1974) [22] . In view of the high yield losses, breeding for resistance is gaining focus, with having ample genetic variability within the host population as the need of the hour. However, the continuous use of high yielding but disease prone wheat varieties coupled with injudicious use of fungicides aggravates the problem. Different researchers have carried their work on different locations and developed predication equation for disease forecasting (Forrest and Nuttar 1989; Viani et al., 2017) [7, 34] , management (Singh et al. 2007; Mahapatra and Das,