Management of late blight of potato through early detection and destruction of disease foci

Spread of late blight of potato from a disease focus was studied in the potato crop (cv. Kufri Chandramukhi) under five different treatments. Disease spread occurred in all the directions of the field. In case of control treatment (without any fungicide spray), the initial disease spread was slow with disease severity of 10.0 per cent, 1.35 m around the disease focus after 41 days of sowing. Quick progress in disease spread with 100 per cent severity was observed on the crop after 79 days of sowing. In treatment with recommended fungicide spray schedule, disease severity of 10 per cent was recorded up to 0.5 m around the disease focus with no further spread of the disease thereafter. In treatment with disease focus killed with herbicide, gramaxone (and no subsequent fungicide spray), the appearance of the disease was delayed with slow progress of the disease. However, no disease was noticed in case of recommended spray schedule with disease focus killed with herbicide.