A Survey On The Incidence Of Rhizome Rot Disease In Major Turmeric Growing Tracts Of South India And Isolation Of Associated Organisms

Abstract

A detailed survey on rhizome rot disease of turmeric (Curcuma longa L.) was conducted in the major turmeric growing tracts of South India. A total of 37 different locations of Andhra Pradesh, Karnataka, Kerala and Tamil Nadu were covered during the survey. The highest disease incidence was noted in Guntur district of Andhra Pradesh (32.22%) followed by Salem district of Tamil Nadu (20.67%). Among the four states surveyed, three locations in Kerala and Andhra Pradesh recorded no disease incidence (0%). According to the information collected, the highest disease incidence and spread of the disease often coincided with the monsoon season of the respective locations. Differences were noted on the system of cultivation, practices of crop rotation and crop protection strategies among the different locations during the survey. The analysis of rhizome rot samples collected during the survey revealed that Pythium is the predominant organism actively involved in the rhizome rot disease. Rhizoctonia and Fusarium are the other organisms found frequently associated with the infected samples. Out of 118 samples, 74.5% yielded Pythium spp., 30.51% yielded Fusarium and 28.8% yielded Rhizoctonia spp. Some samples yielded a combination of these three organisms. The pathogenicity studies of these isolates may prove the role of these organisms for the exact cause of rhizome rot disease in turmeric.