Spatial Distribution of Seedborne Fungi on Pongamia pinnata: A DIVA-GIS Analysis with Reference to Macrophomina phaseolina

Seed health tests were conducted on 176 accessions of Pongamia pinnata (L.) Pierre., an agroforestry tree species collected during the years 2007 and 2008 from the peninsular India covering different districts of Andhra Pradesh (147 samples), Kerala (8), Orissa (20) and Pondicherry (1) by following standard procedures. Many accessions (55 of 176) were found infected with Macrophomina phaseolina with an infection range of 10100%. Grid map was generated for incidence and severity of infection for M. phaseolina using the DIVA-GIS software version 5.2. Highest coefficient of variation percentage for M. phaseolina was observed from Adilabad, Srikakulam and Vizianagaram districts of Andhra Pradesh indicating the regions of higher incidence of the pathogen. Fusarium solani and F. oxysporum were the other important seedborne fungi recorded on P. pinnata accessions from Koraput district of Orissa. Cercospora pongamiae was recorded on samples from both the districts of Orissa with an infection of 20 per cent. Association of saprophytic fungi, viz., Aspergillus spp., Cladosporium sp., Chaetomium sp., Penicillium spp. was also recorded. The present study resulted in identifying the ideal locations for establishing pathogen-free forest nurseries in the south east coastal zone of India and potential regions for exploring resistant sources to M. phaseolina.