Abstract

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

Key words : Alternaria leaf blight; PCR analysis; Biocontrol agents; fungicides; disease suppression period