Efficacy study of some botanical oils against spot blotch disease (Bipolaris sorokiniana) of wheat under In-vitro condition

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.