SURVEY ON NURSERY, FIELD AND POST HARVEST DISEASES OF MEDICINAL PLANTS IN DHAKA, BANGLADESH

Abstract

Three experiments were conducted for detection and identification of diseases of selected medicinal plants at nursery, field and post harvest conditions during January, 2015 to December 2015 in Dhaka, Bangladesh. Ten important medicinal plant species were considered for field survey, viz. Aloe vera (Aloe barbadensis), Akondo (Calotropis gigantea), Arshogondha (Withania somnifera), Bashok (Adhatoda vasica), Dadmordan (Cassia alata), Dhutra (Datura metel), Gulancha (Tinospora cordifolia), Asma lota (Mikania scandens), Tulshi (Ocimum sanctum) and Ulotkambol (Abroma augusta). Only one Aloe vera was considered for nursery and postharvest survey. The disease incidence and severity were recorded under natural epiphytic conditions in three major seasons of Bangladesh, viz. winter, summer and rainy season. In Aloe vera, six diseases were identified in both nursery and field conditions. These were Alternaria leaf spot caused by Alternaria sp., Curvularia leaf spot caused by Curvularia sp., basal rot caused by Fusarium sp., bacterial rot caused by unidentified bacterium, anthracnose caused by Colletotrichum sp. and tip blight caused by Alternaria sp. However, the first four diseases were also identified in postharvest condition. The only identified disease of Akondo and Arshogondha was leaf spot caused by Alternaria spp. Leaf spot disease caused by Alternaria spp. was also identified from Dadmordon, Dhutra, Tulshi, Asma lota and Ulotkambol. In case of Bashok and and Gulancha, two diseases viz. leaf blight caused by Alternaria sp. and leaf spot caused by Alternaria sp. and Cercospora sp. were identified. The incidence and severity of the identified diseases varied significantly among these seasons. The disease incidence and severity were varied 0-36.33% and 0-75%, respectively. In most cases disease incidence and severity were higher in rainy season followed by summer and winter. However, the diseases of Akondo, Arshogondha, Bashok and Dadmordon were highest in winter season. Depending on the disease incidence and severity, the major diseases of inspected medicinal plants were; leaf spot, tip blight, basal rot and bacterial leaf rot of Aloe vera; leaf spot of Arshogondha; Cercospora leaf spot of Bashok and Gulancha.