AT A GLANCE
- Highest risk: December–January, with cool (about 10–20 °C), cloudy, foggy or drizzly weather.
- Protect before symptoms appear — once it spreads, it is very hard to stop.
- Use only registered fungicides bought from licensed dealers, exactly as the label says.
How to recognise it
- Pale green, water-soaked spots on leaf tips and edges that quickly turn brown to black.
- On humid mornings, a white, cottony growth on the underside of leaves around the spots.
- Dark lesions on stems; in severe attacks the whole field looks scorched and gives off a rotting smell.
- Infected tubers show reddish-brown, dry rot just under the skin and rot further in storage.
Prevention and protection
- Plant healthy, certified seed; never use tubers from a blighted crop as seed.
- Prefer varieties bred for late-blight resistance where the disease is frequent.
- Earth up well so tubers stay covered, and avoid excess nitrogen.
- Follow district agro-advisories and CPRI late-blight forecasts; when cool, foggy weather is forecast, apply a recommended protective (contact) fungicide before symptoms appear.
- If the disease appears, switch to a recommended systemic fungicide as advised, and repeat at the interval on the label. Alternate products to avoid resistance.
- Stop irrigation during blight-favourable weather where possible; wet foliage helps it spread.
- In a badly affected field, cut and remove the haulms early and wait about two weeks before digging, so tubers are not infected at harvest.
- Destroy cull piles and volunteer potato plants, which carry the disease to the next season.
Not sure what your crop needs?Send clear photos of the crop — the whole plant, the affected leaves up close, and the field — with your crop and its age. Our team will reply in Hindi or English.
