Strategies for the Management of Leaf Blight Disease Caused by Alternaria alternata in Gloriosa superba (L.)

Meena B,Rajamanickam S,Meena R P,Nalina L

doi:10.29321/maj.10.000485

Abstract

Leaf blight caused by Alternaria alternata (Fr.) Keissler is a severe disease of Gloriosa, causing severe yield loss in every part of Gloriosa growing areas of Tamil Nadu. The foliar pathogen was isolated from disease-infected leaves and proved its pathogenicity. Further, the molecular analysis of the pathogen using 18S rDNA confirmed the pathogen as Alternaria alternata. Attempts were made to explore the biocontrol agents and fungicides for the management of leaf blight incidence under field conditions. Four field trials conducted from 2014 to 2018 revealed that foliar application of talc-based formulation of Bacillus subtilis significantly reduced the leaf blight incidence and increased the seed yield under field conditions. Besides, prophylactic application of these biocontrol agents has also increased the plant growth parameters like plant height, number of flowers/plant, no. of pods/plant and number of seeds/pod. Similarly, foliar application of chlorothalonil (0.1%) and mancozeb (0.2%) was also credited to managing the leaf blight disease under field conditions.

Highlights

Gloriosa superba (L.) an important medicinal crop belongs to Liliaceae family, is an herbaceous and climbing perennial plant commonly known as Climbing-lily, Glory-lily, and Gloriosa lily, and Flamelily
The pathogen was isolated on the potato dextrose agar (PDA) medium using the infected leaves and the morphological characters of the isolated fungus were pertinent to A. alternata as per the original descriptions given by Nees (1817) and quoted by Wallace (1929) and Wiltshire (1933)
The DNA isolated from Alternaria was amplified to a fragment size of 550 bp, products were resolved on a 1.2% agarose gel and their sequence was determined

Summary

Introduction

Gloriosa superba (L.) an important medicinal crop belongs to Liliaceae family, is an herbaceous and climbing perennial plant commonly known as Climbing-lily, Glory-lily, and Gloriosa lily, and Flamelily It comprises rich source of active alkaloid, Colchicine in all the parts, especially the tubers that contain more alkaloid. PGPR aiding in an extensive mechanism such as quorum sensing (QS) and signal interference, exhibiting antimicrobial activity, production of volatile organic compounds (VOCs), induction of systemic resistance, promotion of beneficial plant-microbe symbiosis and interference with pathogen toxin production (Bhattacharyya and Jha, 2012) These reduced the disease progress both directly and indirectly through the production of antimicrobial lipopeptide, including iturin, surfactin, fengycin and bacillomycin D from Bacillus and DAPG and phloroglucinol from Pseudomonas fluorescens.

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