Abstract

Potato late blight is one of the major constraints to potato cultivation in the north eastern hill region of India. Eight popular potato cultivars (Kufri Girdhari, Kufri Megha, Kufri Himsona, Kufri Himalini, Kufri Giriraj, Kufri Jyoti, Kufri Kanchan and Kufri Shailja) were evaluated for late blight disease progress and yield potential with or without the application of fungicide in the field. Blight appeared 103 days after planting (DAP) in Kufri Girdhari and 89 DAP in Kufri Megha in sprayed and unsprayed plots. Minimum terminal disease severity was recorded in Kufri Girdhari (6.5 and 7.5%) followed by Kufri Megha (22.5 and 35%), Kufri Himsona (62.5 and 70%) and Kufri Himalini (70 and 75%) in sprayed and unsprayed plots, respectively. Area under the disease progress curve was lowest on Kufri Girdhari (22.75 and 26.25) followed by Kufri Megha (253.75 and 402.5), Kufri Himalini (934.5 and 1333.5), Kufri Himsona (813.75 and 1162), Kufri Giriraj (1347.5 and 2082.5), Kufri Jyoti (1382.5 and 2117.5), Kufri Kanchan (1277.5 and 1951.25) and Kufri Shailja (1333.5 and 2073.75) in sprayed and unsprayed plots, respectively. There was no significant difference in areas under disease progress curves (AUDPCs) and yield of sprayed and unsprayed plots of Kufri Girdhari, whereas, significant differences (cultivar and spray) were recorded in Kufri Megha, Kufri Himalini and Kufri Himsona. The highest tuber yield was obtained in Kufri Girdhari (34.08 t/ha) and Kufri Himalini (33.48 t/ha). The study revealed that Kufri Girdhari gave highest yield with and without fungicidal applications.

Key words: Late blight, Phytophthora infestans, Solanum tuberosum disease severity, fungicidal spray, cultivars, yield.