Characterization of Chilli Anthracnose Pathogen and its In vitro Management

Abstract

Chilli anthracnose is the most prevalent disease in all major chilli growing areas of the Punjab. Chilli anthracnose is causing the highest yield losses than any other fungal disease. This study was focused to assess the prevalence and incidence of the disease in five major chilli production districts of Punjab. Moreover, morphological and molecular characterization of pathogen and invtiro management by using different techniques of application through five plant extract. Field based surveys were conducted in two years (2014-2015 and 2015-2016) for disease documentation and sample collection followed bylaboratory isolations resulted into the recovery of 142 pathogenic isolates of the pathogen associated with the disease. Disease was recorded in all surveyed area and showed 100% prevalence viz., Vehari, Bahawal Nagar, Okara, Kasur and Rawalpindi. The maximum average incidence 63.10% was recorded at Vehari while minimum average incidence 25.5% was recorded at Rawalpindi.Morphological characterization of the recovered isolates showed variation in morphological characters like two types of colony colours were observed. Fusiform and falcate conidial shapes were recordedand some isolates produced setae while other not. Variations in number of acervuli were also observed. Molecular characterization was done including DNA sequencing of pathogenic isolates though PCR amplification of the Internal Transcription Spacer region using ITS1 and ITS4 primers. Characterization established the identity of the highly pathogenic isolates selected from each district to their morphological characterization done before molecular study. Phylogenetic analysis of 5 morphologically and pathogenically diverse Colletotrichum capsici xxii isolatesexpressed their evolutionary relationship by 99-100% similarity with previously reported isolates available at NCBI database. The most virulent isolate CCO41was used as source of inoculum in in vitro management of the pathogen by using five different plant extracts applied through two different techniques viz., poisoned food technique and well diffusion technique. All applied plant extracts showed antifungal properties and maximum 98.5% growth inhibition was noted down in case of polygonum plant extract @ 0.1% and 0.2% when applied through poisoned food technique while minimum antifungal activity was expressed by dodonaea and clove at the dose of 25μL when applied through well diffusion technique. Poisoned food was found better than well diffusion technique in the study. Results of the study generated exact and comprehensive picture of the disease in major chilli growing areas of the Punjab and indicated the areas at high risk in terms of disease spread. The survey observations also pointed out the trend of decreasing chilli crop area in the all districts due to number of factors including anthracnose. Isolates recovered from the study area were first time studied with details with reference to morphological and molecular characteristics.In vitrobiologicalmanagement studies explored the antifungal potential of indigenous plant against Colletotrichum capsici. Polygonum plant extract was found to be the most effective by suppressing pathogen’s growth up to 98.5% and depicted its antifungal potential.These management findings indicate projected antifungal ability of plant extracts to manage chilli anthracnose in field conditions.