Abstract

A survey was carried out in 2015 at Bangladesh Tea Research Institute (BTRI) to ascertain the impact of varieties, topography, age of plants and shade condition on the incidence and severity of Black rot disease in tea. Data were collected monthly from 300 tea bushes selected randomly for each attribute with three replications. Data were recorded on the incidence and severity of the diseases by observing the typical symptom by using 0-5 scoring scale. Disease incidence and disease index was computed by following a referenced formula. In all the cases of attributes, the maximum level of incidence with Black rot disease was found in September but severity with the same was found in July. The incidence and severity of Black rot disease were significantly higher in hellock (23.52 and 16.64%) areas as compared to flat and tillah areas. Age of tea plants had no variation with severity of the disease but a significant variation was found with the incidence. Highest incidence (22.64%) was found in immature tea bushes. More amount of disease was observed in shaded areas as compared to unshaded areas. Seed tea bush (22.64 and 17.07%) was found to be more predisposed to Black rot disease than clones (20.59 and 16.38%). The findings of this study will help to understand the pattern of distribution of the disease in the commercial tea fields so that the planters can escape the diseases easily.

Key words: Incidence, severity, black rot, tea.