Disease Incidence, Severity and Phenotypic Variation Among the Isolates of Rhizoctonia Bataticola Infected in Root Rot Disease of Mulberry in Different Mulberry Fields of Karnataka

Abstract

The present investigation was carried out in view of destructive nature of root rot disease of mulberry caused by Rhizoctonia bataticola. The pathogen is a soil inhabiting fungus which is causing serious threat to more than 500 plant species. This study will enable to have a clear view of the root rot pathogen, R. bataticola in respect to variability, distribution and economic impact on mulberry plant. Root rot disease of mulberry is a devastating disease among the mulberry diseases. The part of study was conducted in Ramanagara district of Karnataka which is the largest market for silk cocoons in Asia, followed by Kanakapura in Karnataka, India. A field survey was conducted on disease incidence in various mulberry cultivating fields in Kanakapura and Ramanagara areas of Karnataka. Disease incidence of 78% and 53.60% with an average leaf yield loss of 39.73% covering 80 mulberry gardens has been reported in Kanakapura and Ramanagara respectively. From the infected root samples the phytopathogen, R. bataticola was isolated and its phenotypic variation was studied by growing the fungal pathogen on different fugal isolation media such as potato dextrose agar, richard’s agar and czapek dox agar under laboratory conditions. This study revealed the prevalence of the mulberry root rot disease in major mulberry growing locations in Karnataka. Incidence and severity of the mulberry root rot disease varied significantly among the locations under cropping seasons. This study was limited to southern Karnataka and did not cover other mulberry production locations in the different agro-ecological zones in Karnataka state. Therefore a study should be undertaken to evaluate the disease prevalence in other locations.