Deciphering primary incitant of rot complex of small cardamom plant by sequential inoculation of pathogens

Abstract

The major production constraint encountered by small cardamom (Elettaria cardamomum Maton) industry is the wide spread incidence of diseases and pests. Among various diseases that affect the crop, rhizome and root rot diseases are emerging as serious problems in cardamom growing tracts. Soil-borne fungi, Pythium vexans, Rhizoctonia solani and Fusarium oxysporum are found to be the principal pathogens associated with rhizome and root rot diseases of cardamom. In view of different fungi associated with rhizome and root rot diseases, in vitro, glasshouse and in vivo studies were undertaken to identify the sequential events in the colonization and proliferation of each pathogen viz., P. vexans, R. solani and F. oxysporum. Studies on infection process of P. vexans, R. solani and F. oxysporum showed that, P. vexans required only 4 h to colonize the roots, whereas R. solani and F. oxysporum took 12 and 96 h, respectively. The study revealed that, the fungi differed significantly with respect to the events involved in the infection process and pathogenesis. Present investigation helped us to understand that R. solani is primarily associated with rhizome rot in cardamom plantations and P. vexans infection results in seedling rot in nurseries whereas, F. oxysporum was found to cause root rot disease. This information generated from the study is vital in selecting the appropriate fungicide for the management of rot diseases in cardamom and to develop effective and timely disease management strategies against rhizome and root rot pathogens.