Market survey and disease dynamics of post-harvest black mould rot of pomegranate in southern Karnataka

Abstract:

Pomegranate (Punica granatum L.) is an economically important fruit crop widely cultivated in tropical, subtropical, and arid regions. However, post-harvest diseases, particularly black mould rot caused by Aspergillus niger, significantly reduce fruit quality and market value. The present investigation was undertaken to assess the incidence, epidemiology, and pathogenicity of post-harvest black mould fruit rot in major fruit markets of Bengaluru, Tumkuru, Shimoga, and Chitradurga districts of Karnataka. A fortnightly survey was conducted from November-December 2015 to March-April 2016. Disease incidence was recorded from randomly selected fruit samples in retail markets. The results revealed that black mould rot was prevalent throughout the survey period, with incidence ranging from 4.44 to 12.48% and an overall mean incidence of 8.05%. The highest incidence (12.48%) was recorded in April 2016, while the lowest (4.44%) occurred in January 2016, indicating seasonal influence on disease development. Symptomatology included initial skin discoloration, water-soaked lesions, softening of arils, and development of black spore masses leading to complete fruit decay. The pathogen was isolated, purified, and identified based on morphological and cultural characteristics as Aspergillus niger. Pathogenicity tests confirmed Koch’s postulates, as inoculated fruits developed typical symptoms within six days, whereas uninoculated controls remained healthy. Epidemiological studies demonstrated that mechanical injury is a prerequisite for infection. Fruits inoculated without injury did not develop symptoms, emphasizing the importance of careful handling. The study highlights the economic significance of black mould rot and underscores the need for improved post-harvest handling and management strategies to reduce losses and enhance shelf life of pomegranate fruits.