Impact of leaf spot disease on beetroot production in Jaffna peninsula, Sri Lanka

The present study focuses on the aetiology of leaf spot disease and its impact on beetroot production in the Jaffna peninsula. A survey and field study was carried out to understand present status of the disease. The fungus associated with the leaf spot lesions was isolated and identified based on morphological features and sequence analysis. The survey has shown drawbacks in the cultivation practices, such as selection of cultivation season, selection of variety and inadequate weed management practices. The initial symptoms were noted in seedling stage, and the disease incidence and severity progressed with time. The disease incidence and severity index were 85% and 2.71 at 48 days. The field experiment has revealed the negative correlation between leaf spot disease development and yield. The fungal isolates produced obclavate shape, hyaline, multiseptated conidia on dark coloured unbranched sparingly septate conidiophores. The isolates showed 99.25% sequence identity with Cercospora beticola.