Characterization and Fungicide Sensitivity of Fusaria Causing Collar Canker and Dieback in Tea

A collar canker and associated dieback has emerged recently in tea in certain Up and Mid-Country tea growing regions of Sri Lanka. This study was aimed to identify and characterize the pathogens associated with the problem in Mid-Country and evaluate the efficacy of Bitertanol, Hexaconazole, Pyraclostrobin, Tebuconazole and Copper hydroxide fungicides against them. Of a total 96 isolates obtained from symptomatic tissues, randomly selected 09 isolates along with already characterized 4 isolates were used for molecular characterization. Phylogenetic analysis using concatenated ITS and tef sequences further confirmed the pathogens as the members of Fusarium solani species complex (FSSC) clade 3. Growth characterization was performed with 04 representative isolates. The optimum temperature range and pH for growth and sporulation of the isolates were 26 to 30°C and 5.5, respectively. Tebuconazole at 0.05 % (500 ppm) effectively controlled the disease in field. The findings of the study will help to intervene and reduce the economic impact of this recently emerged disease of tea.