Effect of Certain Fungicides and Botanicals against Late Blight of Potato (Phytophthora infestans)

Potato (Solanum tuberosum L.), an important cash crop of India, is prone to many diseases and amongst these, late blight [Phytophthora infestans (Mont) de-Bary] is one of the highly destructive diseases and a major constraint in the profitable cultivation of potato. After realizing the significance of controlling the devastating disease for the sustainability in potato production and thus ensuring more profitability, the present investigation has been conducted with an objective to select the most effective fungicides and botanicals for the management of the disease. The present study was done by KVK, Saharsa during rabi season for consecutive two years (2015-16 and 2016-17) as On-Farm Trial mode at farmers fields of an adopted village of Saharsa district in Bihar. In each trial, there were four treatments including one control i.e. farmers’ practice. The study concludes that the best treatment option to combat late blight disease is Seed treatment with Trichoderma viride @ 5g per kg of seed and spray of Ridomil @ 2g per litre of water starting from 30 DAP alternating with Dimethomorph 1g + ridomil 2g per litre of water at 10 days intervals. The results of economic analysis reveal that highest net return as well as benefit-cost ratio was also highest in Seed treatment with Trichoderma viride @ 5g per kg of seed and spray of Ridomil @ 2g per litre of water starting from 30 DAP alternating with Dimethomorph 1g + ridomil 2g per litre of water at 10 days intervals.